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19-2168; Rev 0; 9/01
MAX1864 Evaluation Kit
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. o 8V to 24V Input Voltage Range o Preset 3.3V Main Output Voltage o 1A Main Output Current o 200kHz Switching Frequency o No Current-Sense Resistor o Linear Regulator Output Voltages 2.5V at 300mA 5.0V at 100mA o Adjustable Output Voltages o Power-Good Output o 16-Pin QSOP Package o Low-Cost Components o Fully Assembled and Tested
Features
Evaluates: MAX1864
Ordering Information
PART MAX1864EVKIT TEMP. RANGE 0C to +70C IC PACKAGE 16 QSOP
Component List
DESIGNATION C1 QTY 1 DESCRIPTION 100F, 35V aluminum electrolytic capacitor Sanyo 35MV100AX 470F, 10V aluminum electrolytic capacitors Sanyo 10MV470AX 0.1F ceramic capacitor (0805) 1F, 10V X5R ceramic capacitor (0805) Taiyo Yuden LMK212BJ105MG 8200pF ceramic capacitor (0805) 10F, 6.3V X5R ceramic capacitors (1210) Taiyo Yuden JMK325BJ106MN or TDK C3216X5R0J106M 4700pF ceramic capacitor (0805) 2200pF ceramic capacitor (0805) 1F, 25V X7R ceramic capacitor (1206) Taiyo Yuden TMK316BJ105ML or TDK C3216X7R1E105M DESIGNATION R1 R2, R5 R3, R4, R12 R6 R7 R8, R10, R11 R9 R13, R14 D1 QTY 1 2 3 1 1 0 0 2 1 DESCRIPTION 47k 5% resistor (0805) 220 5% resistors (0805) 10k 1% resistors (0805) 30.1k 1% resistor (0805) 100k 5% resistor (0805) Not installed (0805) Not installed (short PC trace) 10 5% resistors (0805) Schottky diode Central Semiconductor CMPSH-3 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
C2, C9 C3 C4 C5 C6, C7, C8, C12 C10 C11 C13
2 1 1 1 4 1 1 1
D2
1
N1A, N1B
1
Q1
1
________________________________________________________________ Maxim Integrated Products
1
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.
MAX1864 Evaluation Kit Evaluates: MAX1864
Component List (continued)
DESIGNATION Q2 QTY 1 DESCRIPTION PNP transistor (TO-92) Fairchild 2N3905 or On Semiconductor (Motorola) 2N3905 Transformer Coiltronics VP3-0047 ICE Components (Alternate Supplier) MAX1864TEEE (16-QSOP) MAX1864 PC board MAX1864 data sheet MAX1864 EV kit data sheet Open (cut PC trace)
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 Short (PC trace) ILIM PIN Connected 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. CURRENT-LIMIT THRESHOLD 250mV (default)
T1
1
U1 None None None
1 1 1 1
Adjustable
Component Suppliers
SUPPLIER Central Semiconductor Coilcraft Coiltronics ICE Components International Rectifier Fairchild Nihon On Semiconductor (Motorola) Taiyo Yuden TDK PHONE 631-435-1110 847-639-6400 561-639-5000 703-257-7740 310-322-3331 888-522-5372 661-867-2555 602-303-5454 408-573-4150 547-803-6100 FAX 631-435-1824 847-639-1469 561-742-0134 703-257-7547 310-252-7175 972-910-8036 661-867-2698 602-994-6430 408-573-4159 847-390-4405
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 5k to 50k 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 5k to 50k 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.
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
_______________________________________________________________________________________
VIN C13 1.0F 25V VL (5V) 1 L 3 2R C4 1.0F 10V 16 15 VL BST DH 2 COMP 5 4 N1-B 3 15H 3 OUT 4 FB C11 2200pF R2 220 3 R3 10k 1% Q1 2 C10 4700pF C6 10F 6.3V VOUT2 2.5V AT 300mA T1-F 1 R5 220 1 2 8 R12 10k 1% R6 30.1k 1% 3 C8 10F 6.3V VOUT3 5V AT 100mA Q2 C7 10F 6.3V C9 470F 10V D2 2 7 6 8 T1-E 5 1 R9 SHORT (PC TRACE) 2 11 4 9 T1-B T1-D DL VL 11 R14 10 6 LX 12 1 1 12 3 10 C2 470F 10V R8 OPEN VOUT1 3.3V AT 1A 13 2 N1-A T1-A T1-C C3 0.1F R13 10 7 8 14 9 ILIM R1 47k V+ D1 CMPSH-3 VL C1 100F 35V
8V TO 24V
GND
Figure 1. MAX1864 EV Kit Schematic
JU1 CUT HERE R7 100k 1 POK B2 10 GND C12 10F 6.3V 5 U1
VL
R10 OPEN
R11 OPEN
C5 8200pF
MAX1864
POK
GND FB2 R4 10k 1% 7 6
GND
GND
B3
Evaluates: MAX1864
_______________________________________________________________________________________
FB3
MAX1864 Evaluation Kit
3
MAX1864 Evaluation Kit Evaluates: MAX1864
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 (c) 2001 Maxim Integrated Products Printed USA is a registered trademark of Maxim Integrated Products.

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