MAX15032 500Khz, 36V Output, 600Mw PWM Step-Up DC-DC

19-4232; Rev 0; 8/08

500kHz, 36V Output, 600mW PWM Step-Up DC-DC Converter

General Description Features MAX15032 The MAX15032 constant-frequency, pulse-width-modu- ♦ Input Voltage Range lating (PWM), low-noise boost converter is intended for +2.7V to +5.5V (Using Internal Charge Pump) low-voltage systems that need a locally generated high +5.5V to +11V voltage. This device is capable of generating low-noise, high output voltages, with an output power capability ♦ Wide Adjustable Output Voltage Range: (VIN + 1V) up to 600mW with a 2.9V input voltage. This device can to 36V be used for a wide variety of applications, such as PIN ♦ Output Power: ≥ 600mW for V ≥ 2.9V or varactor diode biasing and LCD displays. The IN MAX15032 operates from +2.7V to +11V. ♦ Internal 0.5Ω (typ), 40V Switch The constant-frequency (500kHz), current-mode PWM ♦ Constant PWM Frequency Provides Easy Filtering architecture provides low-noise output voltage that is in Low-Noise Applications easy to filter. A high-voltage internal lateral DMOS power switch allows this device to boost output volt- ♦ 500kHz (typ) Switching Frequency ages up to 36V. The MAX15032 features a shutdown ♦ 0.5µA (max) Shutdown Current mode to save power. ♦ Internal Soft-Start The MAX15032 is available in a small thermally enhanced 3mm x 3mm 8-pin TDFN package and is ♦ Small Thermally Enhanced 3mm x 3mm 8-Pin specified for operation over the -40°C to +125°C auto- TDFN Package motive temperature range. Applications Ordering Information

Avalanche Photodiode Biasing PIN- TOP PART TEMP RANGE PIN Diode Bias Supplies PACKAGE MARK Low-Noise Varactor Diode Bias Supplies MAX15032ATA+T -40°C to +125°C 8 TDFN-EP* +BKP STB Audio IC Supplies +Denotes a lead-free/RoHS-compliant package. T = Tape and reel. LCD Displays *EP = Exposed pad.

Pin Configuration Typical Operating Circuit

TOP VIEW L1 PGNDCP CN IN 8657 D1 V V = 2.7V TO 5.5V IN LX OUT IN 36V SHDN R1 MAX15032 FB MAX15032 CIN CP COUT PGND CCP R2 + CN GND 1 2 34 LXGND FB SHDN

TDFN

______Maxim Integrated Products 1 For pricing, delivery, and ordering information, please contact Maxim Direct at 1-888-629-4642, or visit Maxim’s website at www.maxim-ic.com. 500kHz, 36V Output, 600mW PWM Step-Up DC-DC Converter

ABSOLUTE MAXIMUM RATINGS IN to GND...... -0.3V to +12V Junction-to-Case Thermal Resistance (θJC) (Note 1) ...... 8°C/W LX to PGND ...... -0.3V to +40V Junction-to-Ambient Thermal Resistance (θJA) FB to GND ...... -0.3V to +12V (Note 1) ...... 41°C/W SHDN to GND...... -0.3V to (VIN + 0.3V) Operating Temperature Range ...... -40°C to +125°C CN to GND ...... -0.3V to +12V Junction Temperature...... +150°C CP to GND...... -0.3V to +12V Storage Temperature Range ...... -65°C to +150°C PGND to GND ...... -0.3V to +0.3V Lead Temperature (soldering, 10s) ...... +300°C Continuous Power Dissipation (TA = +70°C) 8-Pin TDFN (derate 24.4mW/°C above +70°C) ...... 1951.2mW

MAX15032 Note 1: 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.maxim-ic.com/thermal-tutorial. 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.

ELECTRICAL CHARACTERISTICS (VIN = +3.3V, V SHDN = +3.3V, CIN = 10µF, PGND = GND = 0V, TA = TJ = -40°C to +125°C, unless otherwise noted. Typical values are at TA = +25°C. See the Typical Operating Circuit.) (Note 2) PARAMETER SYMBOL CONDITIONS MIN TYP MAX UNITS SUPPLY VOLTAGE

CCP = 10nF 2.7 5.5 Supply Voltage Range VIN V CP connected to IN 5.5 11 V = 1.4V (no switching), C = 10nF, FB CP 12 VIN = 3.3V Supply Current IIN mA V = 1.4V (no switching), CP = IN, FB 1.5 3 VIN = 11V Undervoltage Lockout VUVLO VIN rising 2.375 2.5 2.675 V Undervoltage Lockout Hysteresis VUVLO-HYS 100 mV

Shutdown Current ISHDN V SHDN = 0V 0.5 µA LOGIC INPUT (SHDN) SHDN Input Low Level VIL 0.8 V SHDN Input High Level VIH 2.0 V BOOST CONVERTER Output Voltage Adjustment V + 1 36 V Range IN

Switching Frequency fSW 450 500 550 kHz FB Set Point VFB 1.214 1.245 1.276 V FB Input Bias Current IFB 300 nA

CCP = 10nF, VIN = 2.9V, VCP = 5.5V 0.42 1 ILX = 100mA VIN = 5.5V, VCP = 10V 0.33 1 LX Switch On-Resistance RDS_ON Ω CP connected to VIN = VCP = 5.5V 0.42 1 IN, ILX = 100mA VIN = VCP = 11V 0.33 1

Peak Switch Current Limit ILIM_LX 1 1.33 1.7 A LX Leakage Current VLX = 36V 2 µA Line Regulation ILOAD = 2mA 0.25 %

2 ______500kHz, 36V Output, 600mW PWM Step-Up DC-DC Converter

ELECTRICAL CHARACTERISTICS (continued) MAX15032 (VIN = +3.3V, V SHDN = +3.3V, CIN = 10µF, PGND = GND = 0V, TA = TJ = -40°C to +125°C, unless otherwise noted. Typical values are at TA = +25°C. See the Typical Operating Circuit.) (Note 2) PARAMETER SYMBOL CONDITIONS MIN TYP MAX UNITS

Load Regulation ILOAD = 0 to 20mA, VOUT = 30V 1 % Soft-Start Duration 8ms Soft-Start Steps (0.25 x ILIM_LX) to ILIM_LX 32 Steps THERMAL PROTECTION Thermal Shutdown Rising +160 °C Thermal-Shutdown Hysteresis 8°C

Note 2: All devices are 100% production tested at room temperature (TA = +25°C). All parameter limits through the temperature range are guaranteed by design.

Typical Operating Characteristics (VIN = 3.3V, L1 = 4.7µH, R1 = 143kΩ, R2 = 6.2kΩ, CIN = 10µF, COUT = 2.2µF, CCP = 10nF, see the Typical Operating Circuit. TA = +25°C, unless otherwise noted.)

EFFICIENCY EFFICIENCY EFFICIENCY vs. LOAD CURRENT vs. LOAD CURRENT vs. LOAD CURRENT 85 85 85 VOUT = 36V V = 30V 80 80 OUT 80 VIN = 5V VIN = 5V MAX15032 toc03 75 MAX15032 toc01 75 MAX15032 toc02 75 VOUT = 24V VOUT = 24V 70 70 70 VIN = 5V VIN = 3.3V V = 36V 65 OUT 65 65 V = 3.3V IN VOUT = 30V 60 60 60 VIN = 3.3V 55 55 55 EFFICIENCY (%) EFFICIENCY (%) EFFICIENCY (%) 50 50 50 45 45 45 40 40 40 35 35 35 0202 4 6 8 10 12 14 16 18 0202 4 6 8 10 12 14 16 18 0505 10 15 20 25 30 35 40 45 LOAD CURRENT (mA) LOAD CURRENT (mA) LOAD CURRENT (mA)

______3 500kHz, 36V Output, 600mW PWM Step-Up DC-DC Converter

Typical Operating Characteristics (continued) (VIN = 3.3V, L1 = 4.7µH, R1 = 143kΩ, R2 = 6.2kΩ, CIN = 10µF, COUT = 2.2µF, CCP = 10nF, see the Typical Operating Circuit. TA = +25°C, unless otherwise noted.)

EFFICIENCY MAXIMUM LOAD CURRENT MINIMUM STARTUP VOLTAGE vs. LOAD CURRENT vs. INPUT VOLTAGE vs. LOAD CURRENT 90 360 2.80 L = 4.7μH FOR VOUT = 36V, 30V, AND 24V VOUT = 30V 85 330 2.75 80 300 MAX15032 toc06 MAX15032 toc04 MAX15032 toc05 2.70 75 270 V = 12V VOUT = 12V 2.65 MAX15032 OUT 240 VOUT = 24V 70 VOUT = 12V L = 3.3μH VIN = 5V VIN = 3.3V 210 2.60 65 VOUT = 30V 180 2.55 60 150 2.50

EFFICIENCY (%) 55 120 2.45 50 90 MAXIMUM LOAD CURRENT (mA) 45 MINIMUM STARTUP VOLTAGE (V) 2.40 60 VOUT = 36V 40 2.35 L = 3.3μH 30 35 0 2.30 0505 10 15 20 25 30 35 40 45 2113 4 5 6 7 8 9 10 0202 4 6 8 10 12 14 16 18 LOAD CURRENT (mA) INPUT VOLTAGE (V) LOAD CURRENT (mA)

SUPPLY CURRENT SUPPLY CURRENT SWITCHING FREQUENCY vs. SUPPLY VOLTAGE vs. TEMPERATURE vs. TEMPERATURE 1.6 1.00 550 VFB = 1.4V VFB = 1.4V VIN = 5V 1.4 0.95 540 MAX15032 toc07 MAX15032 toc09 0.90 MAX15032 toc08 530 1.2 0.85 520 1.0 0.80 510 0.8 0.75 500

0.6 0.70 490 SUPPLY CURRENT (mA) SUPPLY CURRENT (mA) 0.65 480 0.4 0.60 SWITCHING FREQUENCY (kHz) 470 0.2 0.55 460 0 0.50 450 2113 4 5 6 7 8 9 10 -40-25 -10 5 20 35 50 65 80 95 110 125 -40-25 -10 5 20 35 50 65 80 95 110 125 SUPPLY VOLTAGE (V) TEMPERATURE (°C) TEMPERATURE (°C)

EXITING SHUTDOWN ENTERING SHUTDOWN SWITCHING WAVEFORMS MAX15032 toc10 MAX15032 toc11 MAX15032 toc12 VIN = 5V VIN = 5V V VSHDN V OUT IOUT = 1mA IOUT = 1mA SHDN (AC-COUPLED) 2V/div 2V/div 50mV/div

VOUT 10V/div VLX 20V/div VOUT 10V/div

I L I 500mA/div L 500mA/div

IOUT = 20mA 1ms/div 20ms/div 1μs/div

4 ______500kHz, 36V Output, 600mW PWM Step-Up DC-DC Converter

Typical Operating Characteristics (continued) MAX15032 (VIN = 3.3V, L1 = 4.7µH, R1 = 143kΩ, R2 = 6.2kΩ, CIN = 10µF, COUT = 2.2µF, CCP = 10nF, see the Typical Operating Circuit. TA = +25°C, unless otherwise noted.)

FB VOLTAGE LOAD-TRANSIENT RESPONSE LINE-TRANSIENT RESPONSE vs. TEMPERATURE MAX15032 toc13 MAX15032 toc14 1.29 RISE TIME = 10ns IOUT = 1mA 1.28 VOUT VIN (AC-COUPLED) MAX15032 toc15 1V/div 200mV/div 1.27 1.26

1.25

FB VOLTAGE (V) 1.24 IOUT VOUT 5mA/div (AC-COUPLED) 1.23 50mV/div 1.22

1.21 100ms/div 2ms/div -40-25 -10 5 20 35 50 65 80 95 110 125 TEMPERATURE (°C)

SWITCH ON-RESISTANCE LX LEAKAGE CURRENT SHUTDOWN SUPPLY CURRENT vs. TEMPERATURE vs. TEMPERATURE vs. TEMPERATURE 1000 50 300 VIN = 5V VLX = 36V VSHDN = 0V 950 45 270

) 900 MAX15032 toc18 MAX15032 toc16 Ω 40 MAX15032 toc17 240 850 35 210 800 750 30 180 700 25 150 650 20 120 600 15 90

550 LX LEAKAGE CURRENT (nA) SWITCH ON-RESISTANCE (m 10 60

500 SHUTDOWN SUPPLY CURRENT (nA) 450 5 30 400 0 0 -40-25 -10 5 20 35 50 65 80 95 110 125 -40-25 -10 5 20 35 50 65 80 95 110 125 -40-25 -10 5 20 35 50 65 80 95 110 125 TEMPERATURE (°C) TEMPERATURE (°C) TEMPERATURE (°C)

OUTPUT VOLTAGE VOUT vs. OPTIMUM vs. LOAD CURRENT INDUCTOR VALUE 30.00 42 29.95 VIN = 2.7V TO 11V 36 MAX15032 toc19 29.90 MAX15032 toc20 29.85 V = 5V IN 30 29.80 (V) 29.75 24 OUT V 29.70 VIN = 3.3V 18 OUTPUT VOLTAGE (V) 29.65 29.60 12 29.55 29.50 6 0202 4 6 8 10 12 14 16 18 3.3 4.7 LOAD CURRENT (mA) LOPTIMUM (μH)

______5 500kHz, 36V Output, 600mW PWM Step-Up DC-DC Converter

Pin Description

PIN NAME FUNCTION Drain of Internal 40V n-Channel DMOS. Connect inductor/diode to LX. Minimize trace area at LX to 1LX reduce switching noise emission. Signal Ground. Connect directly to the local ground plane. Connect GND to PGND at a single point, 2 GND typically near the output capacitor return terminal. Feedback Regulation Point. Connect to the center tap of a resistive divider from the output (V ) to 3FB OUT GND to set the output voltage. The FB voltage regulates to 1.245V (typ). MAX15032 Active-Low Shutdown Control Input. A logic-low voltage on SHDN shuts down the device and reduces 4 SHDN the supply current to 0.5µA (max). Connect SHDN to IN for always-on operation. Do not connect SHDN to a voltage higher than VIN. 5 IN Input Supply Voltage. Bypass IN to PGND with a 4.7µF minimum ceramic capacitor. Negative Terminal of the Charge-Pump Flying Capacitor for 2.7V to 5.5V Supply Voltage Operation. 6CN Leave CN unconnected when the input voltage is in the +5.5V to +11V range. Positive Terminal of the Charge-Pump Flying Capacitor for 2.7V to 5.5V Supply Voltage Operation. 7CP Connect to IN when the input voltage is in the +5.5V to +11V range. Power Ground. Connect the input and output filter capacitors’ negative terminal to PGND. Connect 8 PGND externally to GND at a single point, typically at the output capacitor return terminal. Exposed Pad. Connect EP to a large copper plane at the GND potential to improve thermal —EP dissipation. Do not use as the main GND connection.

Functional Diagram

FB -A

VREF +A LX GND -C SWITCH SOFT- CONTROL N +C START LOGIC PGND

SWITCH CURRENT SENSE CLK

VREF CN CHARGE PUMP OSCILLATOR CP (DOUBLER) 500kHz BIAS AND THERMAL IN REFERENCE SHUTDOWN MAX15032

UVLO

SHDN

6 ______500kHz, 36V Output, 600mW PWM Step-Up DC-DC Converter

Detailed Description tion approaches ideal cycle-by-cycle control over the MAX15032 output voltage since there is no conventional error The MAX15032 constant-frequency, current-mode, amplifier in the feedback path. pulse-width-modulating (PWM) boost converter is intended for low-voltage systems that often need a The device operates in PWM mode using a fixed-fre- locally generated high voltage. This device is capable quency, current-mode operation. The current-mode fre- of generating low-noise, high-output voltage required quency loop regulates the peak inductor current as a for PIN and varactor diode biasing and LCD displays. function of the output error signal. The current-mode The MAX15032 operates either from +2.7V to +5.5V or PWM controller is intended for discontinuous conduc- from +5.5V to +11V. For +2.7V to +5.5V operation, an tion mode (DCM) operation. No internal slope compen- internal charge pump with an external 10nF ceramic sation is added to the current signal. capacitor is used. The MAX15032 also features a shut- Shutdown (SHDN) down logic input to disable the device and reduce its The MAX15032 features an active-low shutdown input standby current to 0.5µA (max). (SHDN). Pull SHDN low to enter shutdown. During shut- The MAX15032 operates in discontinuous mode in order down, the supply current drops to 0.5µA (max). to reduce the switching noise caused by the reverse However, the output remains connected to the input recovery charge of the rectifier diode. Other continuous through the inductor and output rectifier, holding the mode boost converters generate large voltage spikes at output voltage to one diode drop below VIN when the the output when the LX switch turns on because there is MAX15032 shuts down. Connect SHDN to IN for a conduction path between the output, diode, and always-on operation. switch to ground during the time needed for the diode to turn off and reverse its bias voltage. To reduce the out- Charge Pump put noise even further, the LX switch turns off by taking At low supply voltages (+2.7V to +5.5V), an internal 6.8ns typically to transition from “ON” to “OFF.” As a charge-pump circuit and an external 10nF ceramic consequence, the positive slew rate of the LX node is capacitor double the available supply voltage in order reduced and the current from the inductor does not to drive the internal switch efficiently. “force” the output voltage as hard as would be the case In the +5.5V to +11V supply voltage range, the charge if the LX switch were to turn off more quickly. pump must be disabled by connecting CP to IN and Also, the constant-frequency (500kHz) PWM architec- leaving CN unconnected. ture generates an output voltage ripple that is easy to filter. A 40V lateral DMOS device used as the internal Design Procedure power switch makes the device ideal for boost convert- Setting the Output Voltage ers with output voltages up to 36V. Set the MAX15032 output voltage by connecting a The MAX15032 can also be used in other topologies resistive divider from the output to FB to GND (see the where the PWM switch is grounded, like SEPIC and Typical Operating Circuit). Select R2 (FB to GND resis- flyback. tor) between 6kΩ and 10kΩ. Calculate R1 (VOUT to FB resistor) with the following equation: PWM Controller The heart of the MAX15032 current-mode PWM con- ⎡⎛ V ⎞ ⎤ RR12= ⎢⎜ OUT ⎟ − 1⎥ troller is a BiCMOS multi-input comparator that simulta- ⎢⎝ V ⎠ ⎥ neously processes the output-error signal and switch ⎣ FB ⎦ current signal. The main PWM comparator is direct summing, lacking a traditional error amplifier and its where VFB = 1.245V (see the Electrical Characteristics associated phase shift. The direct summing configura- table) and VOUT can range from (VIN + 1V) to 36V.

______7 500kHz, 36V Output, 600mW PWM Step-Up DC-DC Converter

Determining Peak Inductor Current Calculate the optimum value of L (LOPTIMUM) to ensure If the boost converter remains in the discontinuous the full output power without reaching the boundary mode of operation, then the approximate peak inductor between continuous conduction mode (CCM) and DCM current, ILPEAK (A), is represented by the formula using the following formula: below: μ = LHMAX[] 2(××TV− V ) × I LOPTIMUM I = S OUT IN_ MIN OUT 225. LPEAK η × L where: where TS is the period in µs, VOUT is the output voltage in MAX15032 2 − ××η volts, V is the minimum input voltage in volts, I VVVTIN__ MIN() OUT IN MIN S IN_MIN OUT LH[]μ = is the output current in amperes, L is the inductor value in MAX ×× 2 2 IOUT VOUT µH, and η is the efficiency of the boost converter. For a design in which VIN = 3.3V, VOUT = 30V, Determining the Inductor Value η Three key inductor parameters must be specified for IOUT = 20mA, = 0.7, and TS = 2µs, LOPTIMUM = operation with the MAX15032: inductance value (L), 4.7µH: inductor saturation current (ISAT), and DC series resis- LMAX = 10.5µH tance (DCR). In general, the inductor should have a and saturation current rating greater than the maximum LMIN = 3.3µH switch peak current-limit value (ILIM-LX(MAX) = 1.7A). DCR should be below 0.1Ω for reasonable efficiency. For a worst-case scenario in which VIN = 2.9V, VOUT = Due to the high switching frequency of the MAX15032, 30V, IOUT = 20mA, η = 0.7, ILIM-LX(MIN) = 1A, and TS = inductors with a ferrite core or equivalent are recom- 1.8µs: mended to minimize core losses. Table 1 shows a list of LMAX = 9.2µH vendors with 4.7µH inductor parts. and: Table 1. Inductor Vendors LMIN = 2.2µH PART NUMBER The choice of 4.7µH is reasonable given the worst-case VENDOR PHONE FAX OF 4.7µH scenario above. In general, the higher the inductance, INDUCTOR the lower the switching noise.

SLF7045T- Diode Selection TDK 408-437-9585 408-437-9591 4R7M2R0-PF The MAX15032’s high switching frequency demands a high-speed rectifier. Schottky diodes are recommend- TOKO 847-297-0070 847-699-7864 636CY-4R7M+P3 ed for most applications because of their fast recovery Coilcraft 800-322-2645 847-639-1469 MOS6020-472MLC time and low forward-voltage drop. Ensure that the diode’s peak current rating is greater than the inductor Use the following formula to calculate the lower bound peak current. Also, the diode reverse breakdown volt- of the inductor value at different output voltages and age must be greater than VOUT. output currents. This is the minimum inductance value for discontinuous mode operation for supplying the full Output Filter Capacitor Selection 600mW output power: For most applications, use a small ceramic surface-mount output capacitor, 2.2µF or greater. To achieve low output 2 ××TI ×() V− V ripple, a capacitor with low-ESR, low-ESL, and high- μ = S OUT OUT IN_ MIN LHMIN[] capacitance value should be selected. If tantalum or η × I2 LIM− LX electrolytic capacitors are used to achieve high capacitance values, always add a small ceramic in parallel to where VIN (V), VOUT (V), and IOUT (A) are typical val- bypass the high-frequency components of the diode cur- η ues, TS (µs) is the period, is the efficiency, and rent. The higher ESR and ESL of electrolytic increase both ILIM-LX is the peak LX current (A). the output ripple and peak-to-peak transient voltage. Assuming the contribution from the ESR and capacitor

8 ______500kHz, 36V Output, 600mW PWM Step-Up DC-DC Converter

discharge equals 50% (proportions could vary), calcu- diate vicinity of the IC. Bulk aluminum electrolytic MAX15032 late the output capacitance and ESR required for a spec- capacitors might be needed to avoid chattering at low ified ripple using the following equations: input voltages. In the case of aluminum electrolytic capacitors, calculate the capacitor value and ESR of I ⎡ IL× ⎤ the input capacitor using the following equations: CF[]μ= OUT ⎢T − LPEAK OPTIMUM ⎥ OUT × Δ S − 05.(VOUT ⎣⎢ VOUUTV IN_ MIN) ⎦⎥ VI× ⎡ I ××LV⎤ × Δ CF[]μ = OUT OUT ⎢T − LPEAK OPTIMUM OUT ⎥ 05. VOUT IN η ×××Δ S − ESR[] mΩ = VVIN_ MIN05. IN ⎣⎢ VVVIN__ MIN() OUT IN MIN ⎦⎥ IOUT 05. ×××ΔΔVVη ESR[] mΩ = IN IN_ MIN VI× For very low output-ripple applications, the output of the OUT OUT boost converter can be followed by an RC filter to further reduce the ripple. Figure 1 shows a 10Ω, 2.2µF fil- Applications Information ter used to reduce the switching output ripple to Layout Considerations 1mVP-P with a 20mA output and a ripple voltage of Careful PCB layout is critical to achieve clean and sta- 400µVP-P with a 2mA load. The output voltage regulation resistive divider must remain connected to the ble operation. Protect sensitive analog grounds by diode/output capacitor node. using a star ground configuration. Connect GND and PGND together close to the device at the return terminal X7R ceramic capacitors are stable over -40°C to of the output bypass capacitor. Do not connect them +125°C temperature range. Where the automotive tem- together anywhere else. Keep all PCB traces as short perature range is required, use X7R ceramic capaci- as possible to reduce stray capacitance, trace resis- tors. X5R dielectric can be used for -40°C to +85°C tance, and radiated noise. Ensure that the feedback applications. connection to FB is short and direct. Route high-speed Input Capacitor Selection switching nodes away from the sensitive analog areas. Bypass IN (the input voltage pin) to PGND with a mini- Avoid any coupling from LX to FB node by keeping the mum 4.7µF ceramic capacitor. Depending on the sup- FB node away from the LX routing. In addition, decou- ply source impedance, higher values might be needed. pling LX and FB with a small 22pF capacitor from FB to Make sure that the input capacitor is close enough to GND can be used. Use an internal PCB layer for GND the IC to provide adequate decoupling at IN as well. If as an EMI shield to keep radiated noise away from the the layout cannot achieve this, add another 0.1µF device, feedback dividers, and bypass capacitors. ceramic capacitor between IN and PGND in the imme-

L1 4.7μH

RF D1 10Ω V V = 2.9V TO 5.5V IN LX OUT IN 30V SHDN 1A/40V R1 143kΩ MAX15032 FB CIN COUT CF 10μF CP 2.2μF 2.2μF C PGND CP 10nF R2 CN 6.2kΩ GND

Figure 1. Typical Operating Circuit with RC Filter

______9 500kHz, 36V Output, 600mW PWM Step-Up DC-DC Converter

Chip Information Package Information PROCESS: BiCMOS For the latest package outline information and land patterns, go to www.maxim-ic.com/packages.

PACKAGE TYPE PACKAGE CODE DOCUMENT NO. 8 TDFN T833-2 21-0137

MAX15032

Maxim cannot assume responsibility for use of any circuitry other than circuitry entirely embodied in a Maxim product. No circuit patent licenses are implied. Maxim reserves the right to change the circuitry and specifications without notice at any time. 10 ______Maxim Integrated Products, 120 San Gabriel Drive, Sunnyvale, CA 94086 408-737-7600