19-2168; Rev 0; 9/01 MAX1864 Evaluation Kit Features ♦ 8V to 24V Input Voltage Range ♦ Preset 3.3V Main Output Voltage ♦ 1A Main Output Current ♦ 200kHz Switching Frequency ♦ No Current-Sense Resistor ♦ Linear Regulator Output Voltages 2.5V at 300mA 5.0V at 100mA ♦ Adjustable Output Voltages ♦ Power-Good Output ♦ 16-Pin QSOP Package ♦ Low-Cost Components ♦ Fully Assembled and Tested Ordering Information PART TEMP. RANGE MAX1864EVKIT 0°C to +70°C IC PACKAGE 16 QSOP Component List DESIGNATION C1 QTY 1 C2, C9 2 C3 1 C4 1 C5 1 C6, C7, C8, C12 4 C10 1 C11 1 C13 1 DESCRIPTION 100µF, 35V aluminum electrolytic capacitor Sanyo 35MV100AX 470µF, 10V aluminum electrolytic capacitors Sanyo 10MV470AX 0.1µF ceramic capacitor (0805) DESIGNATION QTY R1 1 47kΩ ±5% resistor (0805) DESCRIPTION R2, R5 2 220Ω ±5% resistors (0805) R3, R4, R12 3 10kΩ ±1% resistors (0805) R6 1 30.1kΩ ±1% resistor (0805) R7 1 100kΩ ±5% resistor (0805) R8, R10, R11 0 Not installed (0805) R9 0 Not installed (short PC trace) R13, R14 2 10Ω ±5% resistors (0805) 8200pF ceramic capacitor (0805) 10µF, 6.3V X5R ceramic capacitors (1210) Taiyo Yuden JMK325BJ106MN or TDK C3216X5R0J106M 4700pF ceramic capacitor (0805) D1 1 Schottky diode Central Semiconductor CMPSH-3 D2 1 2200pF ceramic capacitor (0805) 1µF, 25V X7R ceramic capacitor (1206) Taiyo Yuden TMK316BJ105ML or TDK C3216X7R1E105M N1A, N1B 1 Q1 1 1µF, 10V X5R ceramic capacitor (0805) Taiyo Yuden LMK212BJ105MG 0.5A Schottky diode Nihon EP05Q03L or ON Semiconductor (Motorola) MBR0540 Dual N-channel MOSFET International Rectifier IRF7303 or Fairchild NDS9956A PNP transistor (DPAK) Fairchild KSH30 ________________________________________________________________ Maxim Integrated Products For pricing, delivery, and ordering information, please contact Maxim/Dallas Direct! at 1-888-629-4642, or visit Maxim’s website at www.maxim-ic.com. 1 Evaluates: MAX1864 General Description The MAX1864 evaluation kit (EV kit) demonstrates the MAX1864’s standard application circuit. This EV kit operates from 8V to 24V, generating three positive output voltages. The MAX1864 EV kit includes a current-mode synchronous step-down controller and two positive regulator gain blocks. The main synchronous step-down controller provides a 3.3V output voltage with 1A output current from an 8V to 24V input voltage range. The positive regulator gain blocks use an external PNP pass transistor to generate 2.5V with 300mA output current from the main 3.3V output, and 5V with 100mA output current using coupled windings from the step-down converter. The EV kit operates at 200kHz switching frequency, allowing the use of low-cost aluminum electrolytic capacitors and a low-cost power transformer. This EV kit is a fully assembled and tested circuit board. It also allows the evaluation of other main output voltages in the 1.236V to 5.5V range by installing feedback resistors R8 and R9. Evaluates: MAX1864 MAX1864 Evaluation Kit Component List (continued) DESIGNATION QTY Q2 1 T1 1 U1 1 DESCRIPTION PNP transistor (TO-92) Fairchild 2N3905 or On Semiconductor (Motorola) 2N3905 Transformer Coiltronics VP3-0047 ICE Components (Alternate Supplier) MAX1864TEEE (16-QSOP) None 1 MAX1864 PC board None 1 MAX1864 data sheet None 1 MAX1864 EV kit data sheet Component Suppliers SUPPLIER Central Semiconductor Coilcraft PHONE FAX 631-435-1110 631-435-1824 847-639-6400 847-639-1469 Coiltronics 561-639-5000 561-742-0134 ICE Components International Rectifier Fairchild 703-257-7740 703-257-7547 310-322-3331 310-252-7175 888-522-5372 972-910-8036 Nihon 661-867-2555 661-867-2698 On Semiconductor (Motorola) 602-303-5454 602-994-6430 Taiyo Yuden 408-573-4150 408-573-4159 TDK 547-803-6100 847-390-4405 Quick Start The MAX1864 EV kit is fully assembled and tested. Follow these steps to verify board operation. Do not turn on the power supply until all connections are completed. 1) Connect a +8V to +24V supply to the VIN pad. Connect ground to the GND pad. 2) Connect voltmeters to VOUT1, VOUT2, and VOUT3 pads. 3) Turn the power supply on and verify that the output voltages are +3.3V (VOUT1), +2.5V (VOUT2), and +5V (VOUT3). 2 4) See the Evaluating Other Output Voltages section to modify the board for different output voltages. Jumper Settings Table 1. Jumper JU1 Functions (Fixed/Adj. Current-Limit Selection) JU1 ILIM PIN Short (PC trace) Open (cut PC trace) Connected CURRENT-LIMIT THRESHOLD 250mV (default) Connected to VL via voltage divider R10/R11. Refer to the Current-Limit Circuit section in the MAX1864 data sheet for information on selecting R10/R11. Adjustable Evaluating Other Output Voltages The EV kit main output is preset to 3.3V, however the output voltage can also be adjusted between 1.236V and (0.8V x VIN) by selecting R8 and R9 values. Simply cut the PC board trace that is shorting R9, then select feedback resistors R8 and R9. Select R9 in the 5kΩ to 50kΩ range, and calculate R8 with the following equation: R8 = R9 [(VOUT/VFB) - 1] where VFB = 1.236V. For output voltages greater than 5.5V, refer to the Output Voltage Selection section in the MAX1864 data sheet. The positive linear-regulator output voltages are set by connecting a voltage divider from the main output to FB2/FB3 to GND. In the 5kΩ to 50kΩ range, select R4 or R12, and calculate R3 or R6 with the following equation: R3 = R4 [(VOUT/VFB) - 1] R6 = R12 [(VOUT/VFB) - 1] where VFB = 1.24V. _______________________________________________________________________________________ GND GND GND POK R11 OPEN R10 OPEN GND VL C5 8200pF R7 100kΩ VL VL 1 2 9 10 C13 1.0µF 25V R1 47kΩ JU1 CUT HERE 8V TO 24V GND POK U1 VL 15 MAX1864 V+ 16 COMP ILIM 11 12 13 14 C4 1.0µF 10V FB3 B3 FB2 B2 8 7 6 5 3 OUT 4 FB DL LX DH BST VL (5V) L R12 10kΩ 1% R4 10kΩ 1% C3 0.1µF 2 R5 220Ω C10 4700pF R14 10Ω R6 30.1kΩ 1% R3 10kΩ 1% 3 R13 10Ω D1 CMPSH-3 2 R 1 R2 220Ω 5 7 3 1 1 3 1 C8 10µF 6.3V Q2 C11 2200pF 4 2 2 3 2 1 T1-B T1-A C7 10µF 6.3V VOUT2 2.5V AT 300mA C12 10µF 6.3V VOUT3 5V AT 100mA C6 10µF 6.3V Q1 N1-B 6 N1-A 8 C1 100µF 35V C9 470µF 10V 11 12 1 15µH D2 4 3 2 T1-D T1-C 7 9 T1-F 10 6 8 T1-E R9 SHORT (PC TRACE) C2 470µF 10V 5 R8 OPEN VOUT1 3.3V AT 1A Evaluates: MAX1864 VIN MAX1864 Evaluation Kit Figure 1. MAX1864 EV Kit Schematic _______________________________________________________________________________________ 3 Evaluates: MAX1864 MAX1864 Evaluation Kit 1.0" 1.0" Figure 2. MAX1864 EV Kit Component Placement Guide— Component Side Figure 3. MAX1864 EV Kit PC Board Layout—Component Side 1.0" Figure 4. MAX1864 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 © 2001 Maxim Integrated Products Printed USA is a registered trademark of Maxim Integrated Products.