Evaluates: MAX1698 19-1677 Rev 0 4/00 MAX1698 Evaluation Kit General Description Features The MAX1698 evaluation kit (EV kit) is a fully assembled Input Voltage Down to +0.8V and tested circuit board that contains a boost switch- 3x3 White LED Array ing-regulator current source and array of white LEDs. As configured, the circuit is set up to drive 3 banks of 3 Potentiometer-Adjustable Output Current Level series LED arrays at 20mA each however, a wide vari- (LED Brightness Control) ety of other configurations are possible. The IC can be External Low-Loss N-Channel Switch powered from a separate +2.7VDC to +5.5VDC input, while LED power has a wider input range and can be 10nA IC Shutdown Current supplied either from a logic supply or battery source. Operation Up to 500kHz Switching Frequency The MAX1698 features digital soft-start and adjustable lossless LED current control. The MAX1698 EV kit Surface-Mount Components demonstrates low quiescent current, open-circuit pro- Fully Assembled and Tested tection, and up to 90% efficiency for maximum battery life. Operation up to 500kHz allows the use of tiny sur- face-mount components. Component List Ordering Information DESIGNATION QTY DESCRIPTION PART TEMP. RANGE IC PACKAGE 10F, 25V X5R ceramic cap (1812) MAX1698EVKIT 0C to +70C 10 MAX C1 1 Taiyo Yuden TMK432BJ106KM 1F, 25V X5R ceramic cap (1206) Component Suppliers C2 1 Taiyo Yuden TMK316BJ105KL or Murata GRM42-6X7R105K025A SUPPLIER PHONE FAX 1F, 6.3V X5R ceramic cap (0603) C3 1 Central Taiyo Yuden JMK107BJ105KA 516-435-1110 516-435-1824 Semiconductor 40V, 0.5A Schottky diode (SOD-123) Fairchild 408-822-2000 408-822-2102 D1 1 Motorola MBR0540T1 or Motorola 602-303-5454 602-994-6430 Nihon EP05Q04 Murata 814-956-0666 847-238-0490 24V, 350mW zener diode (SOT-23) D2 1 Central Semiconductor CMPZ5253B Nichia America 408-573-0933 408-573-0934 Corporation White LEDs D3D11 9 Nihon USA 661-867-2555 661-867-2698 Nichia NSPW500BS (T-1-3/4) Sumida 708-956-0666 708-956-0702 10H inductor L1 1 Taiyo Yuden 408-573-4150 408-573-4159 Sumida CDRH5D18-100NC Note: Please indicate that you are using the MAX1698 when 30V, 2.2A, N-channel MOSFET contacting these component suppliers. N1 1 (SuperSOT-3) Fairchild Semiconductor FDN337N SuperSOT is a trademark of Fairchild Semiconductor. 500k potentiometer R1 1 Bourns 3352E-1-504 Quick Start R2, R3, R4 3 15 1% resistors (0805) The MAX1698 EV kit is fully assembled and tested. U1 1 MAX1698EUB (10-pin MAX) Follow these steps to verify board operation. Do not JU1 1 3-pin header turn on the power supply until all connections are completed. None 1 Shunt (JU1) None 1 MAX1698 PC board None 1 MAX1698 data sheet None 1 MAX1698 EV kit data sheet Maxim Integrated Products 1 For free samples and the latest literature, visit www.maxim-ic.com or phone 1-800-998-8800. For small orders, phone 1-800-835-8769.MAX1698 Evaluation Kit Main Output Changing Maximum LED Current The maximum LED current is determined by feedback 1) Connect a +2.7V to +5.5V supply to the VCC pad. resistor R2. LED current = 300mV / R2. Resistors R3 Connect the ground to the GND pad. and R4 must also match the value of R2 to balance the 2) Connect a +0.8V to +7V supply to the VBATT pad. current in each LED bank. Refer to the Setting the Connect the ground to the GND pad. Output Current section of the MAX1698 data sheet for 3) Connect a voltmeter to the VOUT pad. more information on selecting other maximum current settings. 4) Verify that shunt JU1 (SHDN) is across pins 1 and 2. 5) Rotate the potentiometer (R1) to the midposition. Evaluating Off-Board LEDs The MAX1698 EV kit can evaluate off-board LEDs. 6) Turn on the power supply, and verify that the output Current resistors R2, R3, and R4 must be removed from is approximately 9.0V and the LEDs are moderately the EV kit. The EV kit LEDs will no longer function. An lit. external feedback resistor must be connected between For instructions on selecting R1, or other means of the FB pad and GND pad. Refer to the Setting the adjusting brightness, refer to the Adjusting LED Current Output Current section of the MAX1698 data sheet for section in the MAX1698 data sheet. more information on selecting the maximum current- setting resistor. Detailed Description The MAX1698 EV kit contains a switching-regulator cur- Evaluating Output Voltages Over +24V rent-source circuit. The circuit requires +2.7V to +5.5V Zener diode D2 clamps the output voltage V at OUT for IC power (VCC) however, the LED power input +24V if the LED array circuit opens. To evaluate output (VBATT) can accept a wide input voltage range from voltages greater than +24V, zener diode D2 must be +0.8V up to the forward voltage of the LED array (+7V replaced. Choose the zener diode +2V above the maxi- for the 3x3 array supplied on the EV kit). The board can mum V . The MOSFET N1 breakdown voltage OUT drive up to +24V for the LED output, as limited by the should exceed the zener voltage. Output capacitor open-circuit protection zener (D2). C2s voltage rating must exceed the zener diode voltage. Output current is adjusted with R1 to control LED brightness. The boost converter operates up to a maxi- Table 1. Jumper JU1 Functions mum frequency of 500kHz. SHUNT MAX1698 SHDN PIN The MAX1698 EV kit can evaluate additional off-board LOCATION OUTPUT LEDs. For instructions on evaluating additional LEDs, MAX1698 enabled, see the Evaluating Off-Board LEDs section. 1 and 2 Connected to VCC V = up to +24V OUT Jumper Selection Shutdown Mode Shutdown mode, 2 and 3 Connected to GND The MAX1698 EV kit features a shutdown mode that V = V - V OUT IN D1 reduces the MAX1698 quiescent current to less than 1A (max), preserving battery life. The three-pin jumper (JU1) selects the shutdown mode for the circuit. Table 1 lists the selectable jumper options. 2 Evaluates: MAX1698