EVALUATION KIT AVAILABLE MAX16904 General Description The MAX16904 is a small, synchronous buck converter with integrated high-side and low-side switches. The device is designed to deliver 600mA with input voltages from +3.5V to +28V while using only 25A quiescent current at no load. Voltage quality can be monitored by observing the PGOOD signal. The MAX16904 can operate in dropout by running at 97% duty cycle, making it ideal for automotive and industrial applications. 2.1MHz, High-Voltage, 600mA Mini-Buck Converter Features Wide +3.5V to +28V Input Voltage Range Tolerates Input Voltage Transients to +42V 600mA Minimum Output Current with Overcurrent Protection Fixed Output Voltages (See the Selector Guide and Contact Factory for All Available Trimmed Output Voltage Options) The MAX16904 operates at a 2.1MHz frequency, allowing for small external components and reduced output ripple. It guarantees no AM band interference. SYNC input programmability enables three frequency modes for optimized performance: forced fixed-frequency operation, SKIP mode (ultra-low quiescent current of 25A), and synchronization to an external clock. The MAX16904 can be ordered with spread-spectrum frequency modulation, designed to minimize EMI-radiated emissions due to the modulation frequency. 2.1MHz Switching Frequency with Three Modes of Operation * 25A Ultra-Low Quiescent Current SKIP Mode * Forced Fixed-Frequency Operation * External Frequency Synchronization The MAX16904 is available in a thermally enhanced, 3mm x 3mm, 10-pin TDFN package or a 16-pin TSSOP package. The MAX16904 operates over the -40C to +125C automotive temperature range. Thermal Shutdown Protection Applications Automotive Industrial Military High-Voltage Input-Power DC-DC Applications Optional Spread-Spectrum Frequency Modulation Power-Good Output Enable-Pin Compatible from +3.3V Logic Level to +42V -40C to +125C Automotive Temperature Range 10-Pin TDFN-EP or 16-Pin TSSOP-EP Packages AEC-Q100 Qualified Ordering Information PART SPREAD TEMP PINSPECTRUM RANGE PACKAGE MAX16904RATB__/V+ Disabled -40C to 10 TDFN-EP* +125C MAX16904RAUE__/V+ Disabled -40C to 16 TSSOP-EP* +125C MAX16904SATB__/V+ Enabled -40C to 10 TDFN-EP* +125C MAX16904SAUE__/V+ Enabled -40C to 16 TSSOP-EP* +125C Note: Insert the desired suffix letters (from Selector Guide) into the blanks to indicate the output voltage. Alternative output voltages available upon request. +Denotes a lead(Pb)-free/RoHS-compliant package. /V denotes an automotive qualified part. *EP = Exposed pad. Selector Guide appears at end of data sheet. 19-5481; Rev 12; 11/15 MAX16904 2.1MHz, High-Voltage, 600mA Mini-Buck Converter Typical Operating Circuits 4.7F * SUP EN 33k VBAT LEVEL SIGNAL MAX16904_50/V+ SYNC BST GND 0.1F 4.7H 5V AT 600mA LX PGOOD 10F 20k PGND BIAS 2.2F OUTS 4.7F * SUP EN 33k VBAT LEVEL SIGNAL MAX16904_33/V+ SYNC BST 0.1F 3.3H 3.3V AT 600mA LX GND PGOOD 10F PGND OUTS 20k BIAS 2.2F *PLACE INPUT SUPPLY CAPACITORS AS CLOSE AS POSSIBLE TO THE SUP PIN. SEE THE APPLICATIONS INFORMATION SECTION FOR MORE DETAILS. www.maximintegrated.com Maxim Integrated 2 MAX16904 2.1MHz, High-Voltage, 600mA Mini-Buck Converter Absolute Maximum Ratings (Voltages referenced to GND.) SUP, EN..................................................................-0.3V to +42V BST to LX (Note 1)....................................................-0.3V to +6V LX (Note 1)................................................-0.3V to (VSUP + 0.3V) BST.........................................................................-0.3V to +47V OUTS......................................................................-0.3V to +12V SYNC, PGOOD, BIAS............................................-0.3V to +6.0V PGND to GND .......................................................-0.3V to +0.3V LX Continuous RMS Current.................................................1.0A OUTS Short-Circuit Duration ......................................Continuous ESD Protection Human Body Model .........................................................2kV Machine Model ..............................................................200V Continuous Power Dissipation (TA = +70C) TDFN (derate 24.4 mW/C above +70C)..................1951mW TSSOP (derate 26.1 mW/C above+70C)................2089mW Operating Temperature Range............................-40C to +125C Junction Temperature.......................................................+150C Storage Temperature Range...............................-65C to +150C Lead Temperature (soldering, 10s)...................................+300C Soldering Temperature (reflow)........................................+260C Stresses beyond those listed under "Absolute Maximum Ratings" may cause permanent damage to the device. These are stress ratings only, and functional operation of the device at these or any other conditions beyond those indicated in the operational sections of the specifications is not implied. Exposure to absolute maximum rating conditions for extended periods may affect device reliability. Package Thermal Characteristics (Note 2) TDFN Junction-to-Ambient Thermal Resistance (JA)...........41C/W Junction-to-Case Thermal Resistance (JC)..................9C/W TSSOP Junction-to-Ambient Thermal Resistance (JA)........38.3C/W Junction-to-Case Thermal Resistance (JC)..................3C/W Note 1: Self protected against transient voltages exceeding these limits for 50ns under normal operation and loads up to the maximum rated output current. Note 2: Package thermal resistances were obtained using the method described in JEDEC specification JESD51-7, using a four-layer board. For detailed information on package thermal considerations, refer to www.maximintegrated.com/thermal-tutorial. Electrical Characteristics (VSUP = +14V, TA = TJ = -40C to +125C, unless otherwise noted. Typical values are at TA = +25C, unless otherwise noted.) PARAMETER Supply Voltage Range Supply Current UV Lockout SYMBOL VSUP ISUP VUVLO MIN VBIAS Bias Current Limit IBIAS TYP 3.5 MAX 28 t < 1s 42 EN = low 4 8 EN = high, no load, 3V < VOUT < 5.5V 25 35 EN = high, continuous, no switching 1 Bias rising 2.8 VUVLO,HYS Hysteresis Bias Voltage www.maximintegrated.com CONDITIONS (Note 3) 3 0.4 +5.5V VSUP +42V 5 10 UNITS V A mA 3.2 V V mA Maxim Integrated 3 MAX16904 2.1MHz, High-Voltage, 600mA Mini-Buck Converter Electrical Characteristics (continued) (VSUP = +14V, TA = TJ = -40C to +125C, unless otherwise noted. Typical values are at TA = +25C, unless otherwise noted.) PARAMETER SYMBOL CONDITIONS MIN TYP MAX UNITS BUCK CONVERTER VOUT VOUT,3.3V VOUT,5V Voltage Accuracy VOUT,5.1V VOUT,5.5V VOUT,6.0V VOUT,8.0V SKIP-Mode Peak Current ISKIP High-Side DMOS RDSON RON,HS Low-Side DMOS RDSON RON,LS DMOS Peak Current-Limit Threshold IMAX tSS Soft-Start Ramp Time LX Rise Time VOUT = 5V, fixed frequency -2.0% +2.5% VOUT = 5V, SKIP mode (Note 4) -2.0% +4.0% VOUT = 3.3V, fixed frequency -2.0% 3.3 +2.5% VOUT = 3.3V, SKIP mode (Note 4) -2.0% 3.3 +4.0% VOUT = 5V, fixed frequency -2.0% 5 +2.5% -2.0% 5 +4.0% -2.0% 5.1 +2.5% -2.0% 5.1 +4.0% VOUT = 5V, SKIP mode (Note 4) VOUT = 5.1V, fixed frequency VOUT = 5.1V, SKIP mode (Note 4) VOUT = 5.5V, fixed frequency 6V VSUP 18V, ILOAD = 0 to 600mA, TA = -40C to +125C -2.0% 5.5 +2.5% VOUT = 5.5V, SKIP mode (Note 4) -2.0% 5.5 +4.0% VOUT = 6.0V, fixed frequency -2.0% 6.0 +2.5% VOUT = 6.0V, SKIP mode (Note 4) -2.0% 6.0 +4.0% VOUT = 8.0V, fixed frequency -2.0% 8.0 +2.5% VOUT = 8.0V, SKIP mode (Note 4) -2.0% 8.0 +4.0% 350 VBIAS = 5V V mA 400 800 m 250 450 m 0.85 1.05 1.22 A 7 8 9 ms tRISE,LX 5 ns Minimum On-Time tON 80 ns PWM Switching Frequency fSW SYNC Input Frequency Range Spread-Spectrum Range www.maximintegrated.com Internally generated fSYNC SS 1.925 2.1 1.8 Spread-spectrum option only +6 2.275 MHz 2.6 MHz % Maxim Integrated 4 MAX16904 2.1MHz, High-Voltage, 600mA Mini-Buck Converter Electrical Characteristics (continued) (VSUP = +14V, TA = TJ = -40C to +125C, unless otherwise noted. Typical values are at TA = +25C, unless otherwise noted.) PARAMETER SYMBOL CONDITIONS MIN TYP MAX UNITS PGOOD PGOOD Threshold PGOOD Debounce VTHR,PGD VOUT rising 88 93 98 VTHF,PGD VOUT falling 88 91 94 tDEB 10 PGOOD High Leakage Current ILEAK,PGD TA = +25C, VPGD VOUT PGOOD Output Low Level VOUT,PGD Sinking 1mA % s 1 A 0.4 V LOGIC LEVELS EN Level EN Input Current SYNC Switching Threshold SYNC Internal Pulldown VIH,EN 2.4 VIL,EN IIN,EN 0.6 VEN = VSUP = +42V, TA = +25C VIH,SYNC 1 1.4 VIL,SYNC 0.4 V A V RPD,SYNC 200 k Thermal Shutdown TSHDN 175 C Thermal Shutdown Hysteresis TSHDN,HYS 15 C THERMAL PROTECTION Note 3: When the typical minimum on-time of 80ns is violated, the device skips pulses. Note 4: Guaranteed by design; not production tested. www.maximintegrated.com Maxim Integrated 5 MAX16904 2.1MHz, High-Voltage, 600mA Mini-Buck Converter Typical Operating Characteristics (VSUP = +14V, TA = +25C, unless otherwise noted.) 5V, FFF MODE 60 50 3.3V, FFF MODE 40 30 20 5V PART 30 20 3.3V PART 10 10 0 40 0 0.1 0.2 0.3 0.4 0.5 0 0.6 8 10 12 14 16 18 20 22 24 26 28 6 LOAD CURRENT (A) MAX16904 toc04 OUTPUT-VOLTAGE CHANGE (%) 3 SKIP MODE 2 1 0 FFF MODE -1 -2 MAX16904 toc03 1 0 -1 -2 -3 -4 6 8 10 12 14 16 18 20 22 24 26 28 INPUT VOLTAGE (V) SHUTDOWN SUPPLY CURRENT vs. INPUT VOLTAGE 15 12 9 6 3 -3 -4 2 INPUT VOLTAGE (V) LOAD REGULATION 4 3 MAX16904 toc05 70 50 LINE REGULATION (ILOAD = 600mA) 4 OUTPUT VOLTAGE CHANGE (%) EFFICIENCY (%) 80 60 SUPPLY CURRENT (A) 90 3.3V, SKIP MODE NO-LOAD SUPPLY CURRENT vs. INPUT VOLTAGE (SKIP MODE) MAX16904 toc02 5V, SKIP MODE SUPPLY CURRENT (A) 100 MAX16904 toc01 EFFICIENCY vs. LOAD CURRENT 0 0.1 0.2 0.3 0.4 0.5 0 0.6 LOAD CURRENT (A) 6 8 10 12 14 16 18 20 22 24 26 28 INPUT VOLTAGE (V) STARTUP RESPONSE (ILOAD = 600mA) SHUTDOWN WAVEFORM (ILOAD = 600mA) MAX16904 toc06 MAX16904 toc07 EN 5V/div VEN 5V/div IINDUCTOR 0.5A/div IL 1A/div 1ms/div www.maximintegrated.com VOUT 5V/div PGOOD 5V/div VPGOOD 5V/div VOUT 5V/div 20s/div Maxim Integrated 6 MAX16904 2.1MHz, High-Voltage, 600mA Mini-Buck Converter Typical Operating Characteristics (continued) (VSUP = +14V, TA = +25C, unless otherwise noted.) LOAD TRANSIENT RESPONSE (3.3V, FIXED MODE) LOAD TRANSIENT RESPONSE (3.3V, SKIP MODE) MAX16904 toc08 MAX16904 toc09 600mA IL 500mA/div 100mA 600mA IL 500mA/div 100mA VOUT 50mV/div AC-COUPLED 5V VBIAS 5V/div VOUT 50mV/div AC-COUPLED 5V VBIAS 5V/div 5V VPGOOD 5V/div 5V VPGOOD 5V/div 40s/div 40s/div LOAD TRANSIENT RESPONSE (5V, FIXED MODE) LOAD TRANSIENT RESPONSE (5V, SKIP MODE) MAX16904 toc11 MAX16904 toc10 600mA IL 500mA/div 100mA 600mA IL 500mA/div 100mA VOUT 50mV/div AC-COUPLED VOUT 50mV/div AC-COUPLED 5V VBIAS 5V/div 5V VBIAS 5V/div 5V VPGOOD 5V/div 5V VPGOOD 5V/div 40s/div 40s/div UNDERVOLTAGE PULSE (COLD CRANK) STANDBY CURRENT vs. LOAD CURRENT MAX16904 toc12 450 VSUP 10V/div VPGOOD 5V/div ILOAD 500mA/div 10ms/div www.maximintegrated.com 400 350 IIN (A) VOUT 5V/div MAX16904 toc13 500 300 250 200 150 100 50 0 0.01 0.1 1 ILOAD (mA) Maxim Integrated 7 MAX16904 2.1MHz, High-Voltage, 600mA Mini-Buck Converter Pin Configurations TOP VIEW BST 1 SUP 2 LX 3 PGND 4 OUTS 5 + MAX16904 EP TDFN 10 EN 9 GND 8 BIAS 7 SYNC 6 PGOOD + BST 1 SUP 2 15 EN SUP 3 14 GND LX 4 LX 5 12 SYNC PGND 6 11 PGOOD PGND 7 OUTS 16 N.C. MAX16904 13 BIAS 10 N.C. EP 8 9 N.C. TSSOP Pin Description PIN NAME FUNCTION TDFN-EP TSSOP-EP 1 1 BST Bootstrap Capacitor for High-Side Driver (0.1F) 2 2, 3 SUP Voltage Supply Input. Connect a 4.7F ceramic capacitor from SUP to PGND. Place the capacitor very close to the SUP pin. For the TSSOP-EP package, connect both SUP pins together for proper operation. 3 4, 5 LX 4 6, 7 PGND Power Ground. For the TSSOP-EP package, connect both PGND pins together for proper operation. 5 8 OUTS Buck Regulator Voltage-Sense Input. Bypass OUTS to PGND with a 10F or larger X7R ceramic capacitor. 6 11 PGOOD 7 12 SYNC Sync Input. SYNC allows the device to synchronize to other supplies. When connected to GND or unconnected, SKIP mode is enabled under light loads. When connected to a clock source or BIAS, forced PWM mode is enabled. 8 13 BIAS +5V Internal Logic Supply. Connect a 2.2F ceramic capacitor from BIAS to GND. Analog Ground 9 14 GND 10 15 EN -- 9, 10, 16 N.C. -- -- EP www.maximintegrated.com Buck Switching Node. LX is high impedance when the device is off. For the TSSOP package, connect both LX pins together for proper operation. Open-Drain Power-Good Output. Enable Input. EN is high-voltage compatible. Drive EN HIGH for normal operation. No Connection. Not internally connected. Exposed Pad. Connect EP to PGND. Do not use EP as the only ground connection. Maxim Integrated 8 MAX16904 2.1MHz, High-Voltage, 600mA Mini-Buck Converter Functional Diagram SYNC EN HVLDO REF BANDGAP OSC BST BIAS SUP CLK SOFT-START OUTS LX BIAS LSD COMP MAX16904 PGOOD www.maximintegrated.com LOGIC CONTROL PWM EAMP VGOOD HSD CURRENT-SENSE AND SLOPE COMPENSATION PGND GND Maxim Integrated 9 MAX16904 Detailed Description The MAX16904 is a small, current-mode buck converter that features synchronous rectification and requires no external compensation network. The device is designed for 600mA output current, and can stay in dropout by running at 97% duty cycle. It provides an accurate output voltage within the +6.5V to +18V input range. Voltage quality can be monitored by observing the PGOOD signal. The device operates at 2.1MHz (typ) frequency, which allows for small external components, reduced output ripple, and guarantees no AM band interference. The device features an ultra-low 25A (typ) quiescent supply current in standby mode. Standby mode is entered when load currents are below 5mA and when SYNC is low. The device operates from a +3.5V to +28V supply voltage and tolerates transients up to +42V, making it ideal for automotive applications. The device is available in factory-trimmed output voltages from 1.8V to 10.7V in 100mV steps. Contact the factory for availability of voltage options. 2.1MHz, High-Voltage, 600mA Mini-Buck Converter the SKIP mode current threshold. If SYNC is at BIAS or has a frequency applied to it, the device is in forced PWM mode. The device offers the best of both worlds. The device can be switched during operation between forced PWM mode and SKIP mode by switching SYNC. SKIP Mode Operation SKIP mode is entered when the SYNC pin is connected to ground or is unconnected and the peak load current is < 350mA (typ). In this mode, the high-side FET is turned on until the current in the inductor is ramped up to 350mA (typ) peak value and the internal feedback voltage is above the regulation voltage (1.2V typ). At this point, both the high-side and low-side FETs are turned off. Depending on the choice of the output capacitor and the load current the high-side FET turns on when OUTS (valley) drops below the 1.2V (typ) feedback voltage. Achieving High Efficiency at Light Loads Enable (EN) The device operates with very low quiescent current at light loads to enhance efficiency and conserve battery life. When the device enters SKIP mode the output current is monitored to adjust the quiescent current. BIAS/UVLO When the output current is < 5mA, the device operates in the lowest quiescent current mode also called the standby mode. In this mode, the majority of the internal circuitry (excluding that necessary to maintain regulation) in the device, including the internal high-voltage LDO, is turned off to save current. Under no load and with SKIP mode enabled, the device draws only 25A (typ) current. For load currents > 5mA, the device enters normal SKIP mode while still maintaining very high efficiency. The device is activated by driving EN high. EN is compatible from a +3.3V logic level to automotive battery levels. EN can be controlled by microcontrollers and automotive KEY or CAN inhibit signals. The EN input has no internal pullup/pulldown current to minimize overall quiescent supply current. To realize a programmable undervoltage lockout level, use a resistor-divider from SUP to EN to GND. The device features undervoltage lockout. When the device is enabled, an internal bias generator turns on. LX begins switching after VBIAS has exceeded the internal undervoltage lockout level VUVLO = 3V (typ). Soft-Start The device features an internal soft-start timer. The output voltage soft-start ramp time is 8ms (typ). If a short circuit or undervoltage is encountered, after the softstart timer has expired, the device is disabled for 30ms (typ) and it reattempts soft-start again. This pattern repeats until the short circuit has been removed. Oscillator/Synchronization and Efficiency (SYNC) The device has an on-chip oscillator that provides a switching frequency of 2.1MHz (typ). Depending on the condition of SYNC, two operation modes exist. If SYNC is unconnected or at GND, the device must operate in highly efficient pulse-skipping mode if the load current is below www.maximintegrated.com Controlled EMI with Forced-Fixed Frequency In forced PWM mode, the device attempts to operate at a constant switching frequency for all load currents. For tightest frequency control, apply the operating frequency to SYNC. The advantage of this mode is a constant switching frequency, which improves EMI performance; the disadvantage is that considerable current can be thrown away. If the load current during a switching cycle is less than the current flowing through the inductor, the excess current is diverted to GND. With no external load present, the operating current is in the 10mA range. Extended Input Voltage Range In some cases, the device is forced to deviate from its operating frequency independent of the state of SYNC. For input voltages above 18V, the required duty cycle to regulate its output may be smaller than the minimum ontime (80ns, typ). In this event, the device is forced to lower its switching frequency by skipping pulses. Maxim Integrated 10 MAX16904 If the input voltage is reduced and the device approaches dropout, it tries to turn on the high-side FET continuously. To maintain gate charge on the high-side FET, the BST capacitor must be periodically recharged. To ensure proper charge on the BST capacitor when in dropout, the high-side FET is turned off every 6.5s and the low-side FET is turned on for about 150ns. This gives an effective duty cycle of > 97% and a switching frequency of 150kHz when in dropout. Spread-Spectrum Option The device has an optional spread-spectrum version. If this option is selected, then the internal operating frequency varies by +6% relative to the internally generated operating frequency of 2.1MHz (typ). Spread spectrum is offered to improve EMI performance of the device. By varying the frequency 6% only in the positive direction, the device still guarantees that the 2.1MHz frequency does not drop into the AM band limit of 1.8MHz. Additionally, with the low minimum on-time of 80ns (typ) no pulse skipping is observed for a 5V output with 18V input maximum battery voltage in steady state. The internal spread spectrum does not interfere with the external clock applied on the SYNC pin. It is active only when the device is running with internally generated switching frequency. Power-Good (PGOOD) The device features an open-drain power-good output. PGOOD is an active-high output that pulls low when the output voltage is below 91% of its nominal value. PGOOD is high impedance when the output voltage is above 93% of its nominal value. Connect a 20k (typ) pullup resistor to an external supply or the on-chip BIAS output. Overcurrent Protection The device limits the peak output current to 1.05A (typ). To protect against short-circuit events, the device shuts off when OUTS is below 1.5V (typ) and one overcurrent event is detected. The device attempts a soft-start restart every 30ms and stays off if the short circuit has not been removed. When the current limit is no longer present, it reaches the output voltage by following the normal softstart sequence. If the device die reaches the thermal limit of +175C (typ) during the current-limit event, it immediately shuts off. Thermal-Overload Protection The device features thermal-overload protection. The device turns off when the junction temperature exceeds +175C (typ). Once the device cools by 15C (typ), it turns back on with a soft-start sequence. www.maximintegrated.com 2.1MHz, High-Voltage, 600mA Mini-Buck Converter Applications Information Inductor Selection The nominal inductor value can be calculated using Table based on the nominal output voltage of the device. Select the nearest standard inductance value to the calculated nominal value. The nominal standard value selected should be within 25% of LNOM for best performance. Table 1. Inductor Selection VOUT (V) LNOM (H) 1.8 to 3.1 VOUT/0.55 3.2 to 6.5 VOUT/0.96 6.6 to 8.1 VOUT/1.40 8.2 to 10 VOUT/1.75 Table 2. Examples for Standard Output Voltages VOUT (V) CALCULATED LNOM (H) STANDARD VALUE (H) 1.8 3.3 3.3 3.3 3.4 3.3 5.0 5.2 4.7 8.0 5.7 5.6 Input Capacitor A low-ESR ceramic input capacitor of 1F or larger is needed for proper device operation. This value may need to be larger based on application input ripple requirements. The discontinuous input current of the buck converter causes large input ripple current. The switching frequency, peak inductor current, and the allowable peak-to-peak input-voltage ripple dictate the input capacitance requirement. Increasing the switching frequency or the inductor value lowers the peak-to-average current ratio yielding a lower input capacitance requirement. The input ripple comprises mainly of VQ (caused by the capacitor discharge) and VESR (caused by the ESR of the input capacitor). The total voltage ripple is the sum of VQ and VESR. Assume the input-voltage ripple from the ESR and the capacitor discharge is equal to 50% each. The following equations show the ESR and capacitor requirement for a target voltage ripple at the input: Maxim Integrated 11 MAX16904 2.1MHz, High-Voltage, 600mA Mini-Buck Converter VESR IP-P I OUT + 2 x D(1 - D) I C IN = OUT VQ x f SW ESR = where: (VIN - VOUT )x VOUT IP-P = VIN x f SW xL and: D= VOUT VIN where IOUT is the output current, D is the duty cycle, and fSW is the switching frequency. Use additional input capacitance at lower input voltages to avoid possible undershoot below the UVLO threshold during transient loading. Output Capacitor To maintain acceptable phase margin, a minimum ceramic output capacitor value of 10F is needed with a voltage rating of 2 times the VOUT voltage. Additional output capacitance may be needed based on application-specific output voltage ripple requirements. The allowable output-voltage ripple and the maximum deviation of the output voltage during step load currents determine the output capacitance and its ESR. The output ripple comprises of VQ (caused by the capacitor discharge) and VESR (caused by the ESR of the output capacitor). Use low-ESR ceramic or aluminum electrolytic capacitors at the output. For aluminum electrolytic capacitors, the entire output ripple is contributed by VESR. Use the ESROUT equation to calculate the ESR requirement and choose the capacitor accordingly. If using ceramic capacitors, assume the contribution to the output ripple voltage from the ESR and the capacitor discharge to be equal. The following equations show the output capacitance and ESR requirement for a specified output-voltage ripple. ESR = C OUT = www.maximintegrated.com VESR IP-P IP-P 8 x VQ x f SW where: (VIN - VOUT ) x VOUT IP-P = VIN x f SW xL VOUT_RIPPLE VESR + VQ IP-P is the peak-to-peak inductor current as calculated above and fSW is the converter's switching frequency. The allowable deviation of the output voltage during fast transient loads also determines the output capacitance and its ESR. The output capacitor supplies the step load current until the converter responds with a greater duty cycle. The response time (tRESPONSE) depends on the closed-loop bandwidth of the converter. The device's high switching frequency allows for a higher closed-loop bandwidth, thus reducing tRESPONSE and the output capacitance requirement. The resistive drop across the output capacitor's ESR and the capacitor discharge causes a voltage droop during a step load. Use a combination of low-ESR tantalum and ceramic capacitors for better transient load and ripple/noise performance. Keep the maximum output-voltage deviations below the tolerable limits of the electronics being powered. When using a ceramic capacitor, assume an 80% and 20% contribution from the output capacitance discharge and the ESR drop, respectively. Use the following equations to calculate the required ESR and capacitance value: ESR OUT = VESR I STEP I xt C OUT = STEP RESPONSE VQ where ISTEP is the load step and tRESPONSE is the response time of the converter. The converter response time depends on the control-loop bandwidth. PCB Layout Guidelines Careful PCB layout is critical to achieve low switching power losses and clean stable operation. Use a multilayer board wherever possible for better noise immunity. Refer to the MAX16904 Evaluation Kit for recommended PCB layout. Follow these guidelines for a good PCB layout: 1) The input capacitor (4.7F, see the applications schematic in the Typical Operating Circuits) should be placed right next to the SUP pins (pins 2 and 3 on the TSSOP-EP package). Because the device operates at 2.1MHz switching frequency, this placement is critical for effective decoupling of high-frequency noise from the SUP pins. Maxim Integrated 12 MAX16904 2.1MHz, High-Voltage, 600mA Mini-Buck Converter 2) Solder the exposed pad to a large copper plane area under the device. To effectively use this copper area as heat exchanger between the PCB and ambient, expose the copper area on the top and bottom side. Add a few small vias or one large via on the copper pad for efficient heat transfer. Connect the exposed pad to PGND ideally at the return terminal of the output capacitor. 3) Isolate the power components and high current paths from sensitive analog circuitry. 4) Keep the high current paths short, especially at the ground terminals. The practice is essential for stable jitter-free operation. 5) Connect the PGND and GND together preferably at the return terminal of the output capacitor. Do not connect them anywhere else. 1M CHARGE-CURRENTLIMIT RESISTOR HIGHVOLTAGE DC SOURCE CS 100pF 7) Route high-speed switching nodes away from sensitive analog areas. Use internal PCB layers as PGND to act as EMI shields to keep radiated noise away from the device and analog bypass capacitor. ESD Protection The device's ESD tolerance is rated for Human Body Model and Machine Model. The Human Body Model discharge components are CS = 100pF and RD = 1.5k (Figure 1). The Machine Model discharge components are CS = 200pF and RD = 0 (Figure 2). RD 1.5k RD 0 DISCHARGE RESISTANCE STORAGE CAPACITOR Figure 1. Human Body ESD Test Circuit www.maximintegrated.com 6) Keep the power traces and load connections short. This practice is essential for high efficiency. Use thick copper PCB to enhance full load efficiency and power dissipation capability. DEVICE UNDER TEST HIGHVOLTAGE DC SOURCE CHARGE-CURRENTLIMIT RESISTOR CS 200pF DISCHARGE RESISTANCE DEVICE UNDER TEST STORAGE CAPACITOR Figure 2. Machine Model ESD Test Circuit Maxim Integrated 13 MAX16904 2.1MHz, High-Voltage, 600mA Mini-Buck Converter Selector Guide OUTPUT VOLTAGE (V) PIN-PACKAGE SPREAD-SPECTRUM SWITCHING FREQUENCY TOP MARK MAX16904RATB50/V+ 5.0 10 TDFN-EP* (3mm x 3mm x 0.75mm) -- AVY MAX16904RAUE50/V+ 5.0 16 TSSOP-EP* (5mm x 4.4mm) -- -- MAX16904SATB50/V+ 5.0 10 TDFN-EP* (3mm x 3mm x 0.75mm) Yes AWA MAX16904SATB51/V+ 5.1 10 TDFN-EP* (3mm x 3mm x 0.75mm) Yes AYX MAX16904SATB52/V+ 5.2 10 TDFN-EP* (3mm x 3mm x 0.75mm) Yes AYY MAX16904SAUE50/V+ 5.0 16 TSSOP-EP* (5mm x 4.4mm) Yes -- MAX16904RATB33/V+ 3.3 10 TDFN-EP* (3mm x 3mm x 0.75mm) -- AVX MAX16904RAUE33/V+ 3.3 16 TSSOP-EP* (5mm x 4.4mm) -- -- MAX16904SATB33/V+ 3.3 10 TDFN-EP* (3mm x 3mm x 0.75mm) Yes AVZ MAX16904SAUE33/V+ 3.3 16 TSSOP-EP* (5mm x 4.4mm) Yes -- MAX16904RAUE18/V+** 1.8 16 TSSOP-EP* (5mm x 4.4mm) -- -- MAX16904SATB60/V+ 6.0 10 TDFN-EP* (3mm x 3mm x 0.75mm) Yes AYO MAX16904SATB80/V+ 8.0 10 TDFN-EP* (3mm x 3mm x 0.75mm) Yes AYN MAX16904RATB33+ 3.3 10 TDFN-EP* (3mm x 3mm x 0.75mm) -- AZR MAX16904RATB50+ 5.0 10 TDFN-EP* (3mm x 3mm x 0.75mm) -- AYG MAX16904RATB55/V+** 5.5 10 TDFN-EP* (3mm x 3mm x 0.75mm) -- AYL MAX16904RAUE33+ 3.3 16 TSSOP-EP* (5mm x 4.4mm) -- -- MAX16904RAUE50+ 5.0 16 TSSOP-EP* (5mm x 4.4mm) -- -- MAX16904SATB33+ 3.3 10 TDFN-EP* (3mm x 3mm x 0.75mm) Yes AZS MAX16904SATB41/V+** 4.1 10 TDFN-EP* (3mm x 3mm x 0.75mm) Yes BAC PART www.maximintegrated.com Maxim Integrated 14 MAX16904 2.1MHz, High-Voltage, 600mA Mini-Buck Converter Selector Guide (continued) OUTPUT VOLTAGE (V) PIN-PACKAGE SPREAD-SPECTRUM SWITCHING FREQUENCY TOP MARK MAX16904SATB50+ 5.0 10 TDFN-EP* (3mm x 3mm x 0.75mm) Yes AZT MAX16904SATB55/V+ 5.5 10 TDFN-EP* (3mm x 3mm x 0.75mm) Yes BAG MAX16904SAUE33+ 3.3 16 TSSOP-EP* (5mm x 4.4mm) Yes -- MAX16904SAUE50+ 5.0 16 TSSOP-EP* (5mm x 4.4mm) Yes -- PART Note: All devices operate over the -40C to +125C automotive temperature range. +Denotes a lead(Pb)-free/RoHS-compliant package. /V denotes an automotive qualified part. *EP = Exposed pad. **Future product--contact factory for availability. Chip Information PROCESS: BiCMOS www.maximintegrated.com Package Information For the latest package outline information and land patterns (footprints), go to www.maximintegrated.com/packages. Note that a "+", "#", or "-" in the package code indicates RoHS status only. Package drawings may show a different suffix character, but the drawing pertains to the package regardless of RoHS status. PACKAGE TYPE PACKAGE CODE OUTLINE NO. LAND PATTERN NO. 10 TDFN-EP T1033+1 21-0137 90-0003 16 TSSOP-EP U16E+3 21-0108 90-0120 Maxim Integrated 15 MAX16904 2.1MHz, High-Voltage, 600mA Mini-Buck Converter Revision History REVISION NUMBER REVISION DATE PAGES CHANGED DESCRIPTION 0 9/10 Initial release -- 1 11/10 Added new output voltage trim to Selector Guide 12 2 3/11 Updated the Voltage Accuracy and the DMOS Peak Current-Limit Threshold parameters in the Electrical Characteristics, updated TOCs 1, 6, and 8-13 3 7/11 Added the MAX16904RATB50+ part number to the Selector Guide 13 4 3/12 Added new future part numbers to the Selector Guide 13 5 6/12 Updated Selector Guide to include MAX16904SATB51/V+ and the MAX16904SATB52/V+ 6 4/13 Updated Pin Description, Inductor Selection, Input Capacitor, Output Capacitor, and Selector Guide sections 1, 7, 10, 11, 13 7 8/13 Added limits for 5.1V, 6V, and 8V options in Electrical Characteristics and update Selector Guide 3, 13, 14 8 12/13 Added condition for Supply Current and Voltage Accuracy in Electrical Characteristics and removed future product indicator from MAX16904SATB52/V+ 2, 13 9 9/14 Updated Typical Operating Circuit and PGOOD high leakage current conditions in Electrical Characteristics 2, 4 10 3/15 Added new Note 1 in Absolute Maximum Ratings section and renumbered remaining notes in Package Thermal Characteristics and Electrical Characteristics sections 3, 4 11 9/15 Added VOUT 5.5V parts to Electrical Characteristics and Selector Guide tables; updated PGOOD Threshold min/max values in Electrical Characteristics table 12 11/15 Removed future product reference to MAX16904SATB55/V+ in Selector Guide 3, 4, 5, 6 13 3, 4, 13, 14 15 For pricing, delivery, and ordering information, please contact Maxim Direct at 1-888-629-4642, or visit Maxim Integrated's website at www.maximintegrated.com. Maxim Integrated cannot assume responsibility for use of any circuitry other than circuitry entirely embodied in a Maxim Integrated product. No circuit patent licenses are implied. Maxim Integrated reserves the right to change the circuitry and specifications without notice at any time. The parametric values (min and max limits) shown in the Electrical Characteristics table are guaranteed. Other parametric values quoted in this data sheet are provided for guidance. Maxim Integrated and the Maxim Integrated logo are trademarks of Maxim Integrated Products, Inc. (c) 2015 Maxim Integrated Products, Inc. 16 Mouser Electronics Authorized Distributor Click to View Pricing, Inventory, Delivery & Lifecycle Information: Maxim Integrated: MAX16904RATB33/V+T MAX16904RATB50/V+T MAX16904RAUE33/V+ MAX16904RAUE33/V+T MAX16904RAUE50/V+ MAX16904RAUE50/V+T MAX16904SATB33/V+T MAX16904SATB50/V+T MAX16904SAUE33/V+ MAX16904SAUE33/V+T MAX16904SAUE50/V+ MAX16904SAUE50/V+T MAX16904RATB50+T MAX16904SATB51/V+T MAX16904SATB60/V+T MAX16904SATB80/V+T MAX16904RAUE18/V+ MAX16904RAUE18/V+T MAX16904SATB41/V+T MAX16904SATB52/V+T MAX16904RATB33/V+ MAX16904SAUE33+ MAX16904RAUE50+ MAX16904RAUE33+