19-1749; Rev 0; 10/96 MAX849 Evaluation Kit ____________________Component List DESIGNATION QTY DESCRIPTION BAT1 2 Battery clips Keystone 92 C1 1 0.22µF ceramic capacitor C2, C3 2 0.1µF ceramic capacitors C4, C5 2 4.7nF ceramic capacitors CF1, CF2 2 100µF, 6V, 0.1ESR capacitors AVX TPSD107M010R0100 CF3 0 Open CI1 1 22µF, 6V, low-ESR capacitor AVX TPSD226M025R0200 CI2 0 Open D1 1 0.5A, 20V Schottky diode Motorola MBR0520L J1 1 10-pin header JU1 1 2-pin header JU2 1 3-pin header L1 1 10µH, 1.65A, 4.5mm inductor Sumida CDR74B-100 R1 1 10Ω, 5% resistor R2 1 61.9kΩ, 1% resistor R3 0 2 Open Battery clips Keystone 92 R4, R11 2 1kΩ, 5% resistors R5 1 6.81kΩ, 1% resistor R6, R7, R9, R10 4 1MΩ, 5% resistors R8 1 100kΩ, 5% resistor U1 1 Maxim MAX849ESE ____________________________Features ♦ 250mA to 850mA Output Current! VIN (V) VOUT (V) IOUT (mA) 1.2 3.3 250 2.4 3.3 700 2.4 5.0 500 3.6 5.0 850 ♦ 90% Efficiency ♦ Proven PC Board Layout ♦ Fully Assembled and Tested ♦ 2-Channel Analog-to-Digital Converter (ADC) with Serial Output for Voltage Monitoring ______________Ordering Information PART TEMP. RANGE BOARD TYPE MAX849EVKIT-SO 0°C to +70°C Surface Mount _____________________________________Quick Start This section describes how to operate the MAX849 EV kit, and how to evaluate its performance. Do not turn on the power supply until all connections are completed. 1) Configure the jumper and resistor settings as desired. For a standard 3.3V output and 90% power-OK threshold, close jumper JU1 (Table 1). 2) Insert an AA-size battery cell into the battery clips. Or, connect a 1V to 3V DC power supply to the VIN and GND input pads. Turn on the power supply. Quiescent supply current for the board with no load should be less than 1mA. 3) The EV kit board turns on automatically, and VOUT goes to 3.3V. 4) To operate in high-power PWM mode at a particular frequency between 200kHz and 400kHz, leave JU2 open and drive the CLK/SEL pin with pulses at the desired frequency. Or, let the MAX849 determine its own PWM frequency by connecting JU2 1-2. To operate in low-power PFM mode, connect JU2 2-3. ________________________________________________________________ Maxim Integrated Products 1 For free samples & the latest literature: http://www.maxim-ic.com, or phone 1-800-998-8800 Evaluates: MAX848/MAX849 _______________General Description The MAX849 evaluation kit (EV kit) is an assembled and tested PC board that implements a complete, one-cell to three-cell, high-power, low-noise, step-up DC-DC power converter that’s ideal for portable phones and other battery-operated equipment. With a 3.3V output voltage, use one or two cells to get a 250mA to 700mA output current. With a 5V output voltage, use three cells or one lithium-ion (Li-Ion) battery to get an 850mA output current. The board includes clips for a standard AA-size battery, and provides a 10-pin header for user interfacing. To evaluate the MAX848, order a free sample of the MAX848ESE along with the MAX849 EV kit. Evaluates: MAX848/MAX849 MAX849 Evaluation Kit _______________Detailed Description Evaluating the MAX848 To evaluate the MAX848, first replace U1 with a MAX848ESE. Then remove filter capacitor CF2, replace input capacitor CI1 with 10µF, and replace L1 with a 22µH, 800mA inductor. Table 2 lists recommended component changes for MAX848 evaluation. Table 1. Jumper Function Table JUMPER FUNCTION VOUT and POK set by R3, R5, and R2. Open JU1 Closed (default) 3.3V, 10% trip threshold Low-noise PWM mode. CLK/SEL pin is tied to VOUT. 1-2 Reading the Analog-to-Digital Converter (ADC) The MAX849’s internal ADC produces a pulse train on the DOUT pin, at the CLK/SEL switching frequency. Pulses are skipped in proportion to the selected analog input. One way to read a value from the ADC is to use a microcontroller’s (µC's) pulse accumulator or counter/ timer. With the MAX849’s DOUT incrementing the counter, clear it and latch its value after 256 CLK/SEL pulses. The counter’s value will be proportional to the analog input voltage. If the MAX849 is operated in free-running PWM mode (JU2 = 1-2), then the µC must sense the pulse frequency so it can sample DOUT for the correct period of time. Use the LX output to measure the MAX849’s internal frequency. If the MAX849 is operated in synchronized PWM mode (JU2 = open and CLK/SEL driven externally), then the µC should use the CLK/SEL pulses to time the DOUT sampling period. The ADC is not active when CLK/SEL is driven low (JU2 = 2-3). STATE JU2 PWM synchronized to usersupplied CLK/SEL signal. Open 2-3 (default R9) Low-power PFM mode. CLK/SEL pin is tied to GND. Table 2. Recommended Component Changes for MAX848 Evaluation DESIGNATION QTY CF2 0 Open FUNCTION CI1 1 10µF, 6V, low-ESR capacitor AVX TPSD106M035R0300 (10µF, 35V, 0.300Ω max ESR) L1 1 22µH, 800mA inductor Sumida CD54-220 (22µH, 1.11A, 0.18Ω) U1 1 MAX848ESE Setting VOUT and POK Thresholds When V OUT is in regulation, FB = 1.25V, and when VOUT falls to its trip threshold, POKIN drops to 1.25V. Select R3, R5, and R2 by the following method: VOUT = Nominal output voltage VTRIP = Desired POK trip threshold IBIAS = Desired resistor bias current, at least 10µA VREF = 1.25V R2 = VREF / IBIAS R5 = R2 (VOUT - VTRIP) / VTRIP R3 = (R2 + R5) [(VTRIP / VREF) - 1] To set VOUT = 5.0V, set R3 to 178kΩ (do not connect or disconnect JU1 or R3 while the power is on). 2 _______________________________________________________________________________________ MAX849 Evaluation Kit Evaluates: MAX848/MAX849 VOUT1 ON2 LX ON1 1 AIN1 2 AIN2 0.22µF CC1210 3 4 5 6 C2 7 8 POK 0.1µF CC1206 16 AIN1 MAX849 ON1 AIN2 ON2 REF POUT LX GND OUT POKIN FB POK 14 13 11 CLK/SEL 10 DATA 9 AINSEL VIN1 VIN C3 0.1µF CC1210 CF1, CF2, CF3 100µF 10V CI1, CI2 22µF 6V BAT1 GND1 PGND EXTCLK DATA AINSEL VOUT VOUT JU2 JUMPER2 R2 61.9kΩ, 1% JU1 LX 12 PGND L1 SUMIDA CDR74B-100 10µH, 1.65A 15 R5 6.81kΩ, 1% R3 OPEN R1 10Ω D1 MOTOROLA MBR0520L U1 C1 1 2 R8 100k 3 POKIN VOUT AGND AGND FB = AGND FOR 3.3V OUTPUT POKIN = AGND FOR DEFAULT 10% TRIP THRESHOLD ON1 ON2 EXTCLK AINSEL 1M R6 1M R7 1M R9 1M R10 AIN1 R4, 1k OPTIONAL µP INTERFACE 10-PIN HEADER VOUT EXTCLK DATA J4-1 J4-2 ON1 J4-3 ON2 J4-2 LX J4-6 J4-7 AINSEL J4-8 POK J4-9 J4-10 AGND1 R4, 1k AIN1 C4 4.7nF CC1206 CC1206 AIN2 J4-5 AGND AGND AIN2 C5 4.7nF CC1206 CC1206 AGND AGND Figure 1. MAX849 EV Kit Schematic _______________________________________________________________________________________ 3 Evaluates: MAX848/MAX849 MAX849 Evaluation Kit Figure 2. MAX849 EV Kit Component Placement Guide Figure 3. MAX849 EV Kit PC Board Layout—Component Side Figure 4. MAX849 EV Kit PC Board Layout—Solder Side 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. 4 ___________________Maxim Integrated Products, 120 San Gabriel Drive, Sunnyvale, CA 94086 (408) 737-7600 © 1996 Maxim Integrated Products Printed USA is a registered trademark of Maxim Integrated Products.