Evaluates: MAX1687 /MAX1688 19-1426 Rev 0 2/99 MAX1688 Evaluation Kit General Description Features The MAX1688 evaluation kit (EV kit) is a boost switching 2.7V to 6V Input Voltage Range regulator for one Li-Ion cell or three NiCd/NiMH cells in 5V Output Voltage battery-powered systems. The EV kit accepts a positive input between 2.7V and 6V and converts it to a 5V out - Less than 500mV Output Voltage Droop with put. It can easily deliver the current burst required for 1.42A Burst Current cell-phone power amplifier systems. The MAX1688 90% Efficiency reduces battery surge current by slowly charging a reservoir capacitor, which supplies the necessary peak Output Disconnected from Input during Shutdown energy for the current burst. As a result, the peak battery 600kHz Switching Frequency input current is limited, thereby minimizing the battery voltage sag and transient dips. The EV kit operates at Internal MOSFET and Synchronous Rectifier 600kHz, allowing the use of small external components. 3A IC Shutdown Current The MAX1688 EV kit provides low quiescent current and high efficiency for maximum battery life. An internal Surface-Mount Components (TSSOP Package) synchronous rectifier is used to provide over 90% con- Fully Assembled and Tested version efficiency. This EV kit is a fully assembled and tested surface-mount circuit board. The MAX1688 EV kit can also be used to evaluate the MAX1687. Ordering Information Component List DESIGNATION QTY DESCRIPTION PART TEMP. RANGE IC PACKAGE 47F, 16V tantalum capacitor MAX1688EVKIT 0C to +70C 16 TSSOP C1 1 AVX TPSC476M016R0350 or Note: To evaluate the MAX1687, order a MAX1687EUE sample Sprague 595D476X0016C2T with the MAX1688 EV kit. C2 1 0.1F ceramic capacitor 1000F, 6.3V electrolytic capacitors* C3, C4 2 Sanyo 6CV1000AX Quick Start C5 0 Not installed The MAX1688 EV kit is fully assembled and tested. 10H inductor Follow these steps to verify board operation. Do not L1 1 Sumida CLS62B-100 or turn on the power supply until all connections are Coiltronics TP2-100 completed. R1 1 60.4k 1% resistor 1) Connect a 3V supply voltage to the VIN pad. R2, R3 2 20.0k 1% resistors Connect the supply ground to the GND pad. R4 1 1M 5% resistor 2) Connect a voltmeter and load, if any, to the VOUT R5 0 Not installed (for MAX1687 only) pad. U1 1 MAX1688EUE 3) Turn on the power supply. None 1 MAX1688 PC board 4) Synchronize the GSM pulse load to the ON signal by None 1 MAX1688 data sheet applying the logic signal that controls the power *For low-profile applications, use Sprague tantalum amplifier to the ON/OFF pad. ON is low when GSM 595108X06R3R2. load is applied. Component Suppliers 5) Verify the output voltage is 5V. For other output volt- ages, refer to the Adjusting the Output Voltage sec- SUPPLIER PHONE FAX tion in the MAX1687/MAX1688 data sheet for instruc- AVX 803-946-0690 803-626-3123 tions on selecting the feedback resistors. Coiltronics 561-241-7876 561-241-9339 Dale-Vishay 402-564-3131 402-563-6418 Sanyo 619-661-6835 619-661-1055 Sprague 603-224-1961 603-224-1430 Sumida 708-956-0666 708-956-0702 Pg Maxim Integrated Products 1 For free samples & the latest literature: MAX1688 Evaluation Kit Evaluating the MAX1687 Detailed Description The MAX1688 EV kit can also be used to evaluate the The MAX1688 EV kit is designed for supplying short-dura - MAX1687. Follow the steps below to evaluate the tion, high-current bursts for GSM cell phone applications. It MAX1687. combines a boost switching regulator, an N-channel power 1) Replace the MAX1688 with a MAX1687EUE. MOSFET, a P-channel synchronous rectifier, and a preci- sion reference in a single, tiny 16-pin TSSOP package. The 2) Install a short at location JU1 to run the MAX1687 EV kit accepts a positive input between 2.7V and 6V and continuously or apply a logic signal for ON/OFF con- trol. converts it to a 5V output with less than 500mV output volt - age droop at 1.4A burst load. The EV kit operates at 3) Turn on the power supply. 600kHz, allowing the use of small external components. 4) Set up the voltage to the MAX1687s LIM pad by For other applications including component value selec- applying an external voltage to the CHG(LIM) pad or tion, refer to the Applications Information section in the by completing the voltage divider (R3/R5). Refer to MAX1687/MAX1688 data sheet. the Adjusting Current Limit (MAX1687) section of the MAX1687/MAX1688 data sheet. L1 10H 13 3 LX2 LX1 14 4 LX1 LX2 U1 VOUT VIN 1 15 IN OUT 2.7V TO 6V 5.0V C1 C3 C4 C2 C5 MAX1688 47F 2 1000F 1000F 16 OPEN 0.1F IN OUT R1 (MAX1687) 16V 6.3V 6.3V 60.4k 1% CHG 5 CHG (LIM) (LIM) 6 FB 7 REF R2 R3 R5 8 20k 20k OPEN NC 1% 1% 12 PGND 9 ON ON/OFF JU1 11 R4 10 VIN PGND AGND 1M Figure 1. MAX1688 EV Kit Schematic 2 Evaluates: MAX1687/MAX1688