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19-1893; Rev 0; 1/01
MAX1775 Evaluation Kit
General Description
The MAX1775 evaluation kit (EV kit) is a fully assembled and tested surface-mount circuit board that contains a dual step-down switching regulator circuit. The circuit is configured for a main output voltage of +3.3V and a core output voltage of +1.8V. The main output provides up to 1.5A, and the core provides up to 500mA of current. Power for the circuit can be provided from a +2.7V to +5.5V DC source. The EV kit can be reconfigured for input voltages up to +28V. The core's input can be powered from the input source or, for higher input voltages, from the main output. The MAX1775 EV kit demonstrates low quiescent current and high efficiency up to 95% for maximum battery life. Operation up to 1.25MHz allows the use of tiny surface-mount components. o +2.7V to +5.5V Input Range o Output Voltages +3.3V Output at 1.5A +1.8V Output at 500mA o Outputs are Adjustable with Resistors o Internal MOSFET Switches (Core Output) o 5A (typ) IC Shutdown Current o Switching Frequency Up to 1.25MHz o Surface-Mount Components o Fully Assembled and Tested
Features
Evaluates: MAX1775
Ordering Information
PART MAX1775EVKIT TEMP. RANGE 0C to +70C IC PACKAGE 16 QSOP
Component List
DESIGNATION C1 QTY 1 DESCRIPTION 10F, 25V X5R ceramic capacitor (1812) Taiyo Yuden TMK432BJ106KM 1F, 25V X7R ceramic capacitors (1206) Taiyo Yuden TMK316BJ105KL 47F, 6.3V low-ESR electrolytic capacitor (POSCAP) Sanyo 6TPA47M 47F 20%, 6.3V tantalum capacitor (C) Sprague-Vishay 592D476X06R3C2T or AVX TPSC476M016R0350 recommended 0.22F, 25V X7R ceramic capacitor (1206) Taiyo Yuden TMK316BJ224KF 10F, 6.3V X5R ceramic capacitors (1206) Taiyo Yuden JMK316BJ106KL Not installed, capacitors (0805) DESIGNATION D1 L1 C2, C5 2 L2 QTY 0 1 1 DESCRIPTION Not installed, Schottky diode Nihon EC31QS04 optional 5.0H, 2.4A inductor Sumida CDRH6D28-5R0NC 5.4H, 1.6A inductor Sumida CDRH5D18-5R4NC +30V/-20V, 5.5A/4.0A N/P-channel MOSFET (SO-8) Fairchild Semiconductor FDS8928A 24.3k 1% resistor (0805) 30.1k 1% resistor (0805) 0.033 1%, 0.5W resistor (2010) Dale WSL-2010-R033-1% 66.5k 1% resistor (0805) 40.2k 1% resistor (0805) MAX1775EEE (16 QSOP) 3-pin headers Shunts (JU1, JU2) MAX1775 PC board MAX1775 data sheet MAX1775 EV kit data sheet
C3
1
P1A/P1B
1
R1 R2 R3 R4 R5 U1 JU1, JU2 None None None None
1 1 1 1 1 1 2 2 1 1 1
C4
1
C6
1
C7, C8 C9, C10
2 0
________________________________________________________________ Maxim Integrated Products
1
For price, delivery, and to place orders, please contact Maxim Distribution at 1-888-629-4642, or visit Maxim's website at www.maxim-ic.com.
MAX1775 Evaluation Kit Evaluates: MAX1775
Component Suppliers
SUPPLIER AVX Dale-Vishay Fairchild Nihon USA Sanyo USA Sprague-Vishay Sumida Taiyo Yuden PHONE 803-946-0690 402-564-3131 408-822-2000 661-867-2555 619-661-6835 603-224-1961 847-956-0666 408-573-4150 FAX 803-626-3123 402-563-6418 408-822-2102 661-867-2698 619-661-1055 603-224-1430 847-956-0702 408-573-4159
The step-down switching regulator main output voltage can be adjusted from +2.5V to +5.5V, and the core output voltage can be adjusted from +1V to +5V with resistors.
Jumper Selection
Shutdown Mode (Main Output) The MAX1775 EV kit features a shutdown mode that reduces the MAX1775 shutdown current to <5A (typ), which preserves battery life. The 3-pin jumper, JU1, selects the shutdown mode for the MAX1775 main output (VMAIN). Table 1 lists the selectable jumper options.
Note: Please indicate that you are using the MAX1775 when contacting these component suppliers.
Table 1. Jumper JU1 Functions
SHUNT LOCATION 1 and 2 2 and 3 SHDNM PIN Connected to VBATT Connected to GND MAX1775 OUTPUT MAX1775 enabled, VMAIN = +3.3V Shutdown mode, VMAIN = 0
Quick Start
The MAX1775 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.
Outputs
1) Verify that shunts JU1 (SHDNM) and JU2 (SHDNC) are across pins 1 and 2. 2) Connect a voltmeter to the VMAIN pad. 3) Connect a +2.7V to +5.5V DC power supply to the VBATT pad. Connect the supply ground to the GND pad. 4) Turn on the power supply and verify that the main output (VMAIN) is +3.3V. 5) Verify that the core output (VCORE) is +1.8V. For instructions on selecting the feedback resistors for other output voltages, refer to the Evaluating Other Output Voltages section. Shutdown Mode (Core Output) The MAX1775 EV kit features a core shutdown mode that reduces the MAX1775 shutdown current, which preserves battery life. The 3-pin jumper, JU2, selects the shutdown mode for the MAX1775 core output (VCORE). Table 2 lists the selectable jumper options.
Table 2. Jumper JU2 Functions
SHUNT LOCATION 1 and 2 2 and 3 SHDNC PIN Connected to CVL Connected to GND MAX1775 OUTPUT CORE output enabled, VCORE = +1.8V Shutdown mode, VCORE = 0
Detailed Description
The MAX1775 EV kit contains a dual step-down switching regulator. A +3.3V main output provides up to 1.5A, and a +1.8V core output provides up to 500mA of current. The EV kit operates from a +2.7V to +5.5V input voltage range. The EV kit can be reconfigured for input voltages up to +28V refer to the Evaluating High Input Voltage Operation section. The MAX1775 EV kit features several jumper-selectable options. Shutdown mode jumpers that reduce the MAX1775 shutdown current to <5A (typ) are provided for the main and core outputs. Another option enables the main output (VMAIN) or an external voltage source to feed power to the core input.
2
Core Input Supply The MAX1775 EV kit features an option that allows the main output voltage source to power the core's input. Jumper JU3 selects which voltage source feeds the core's input. Table 3 lists the jumper options.
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MAX1775 Evaluation Kit
Table 3. Jumper JU3 Functions
PIN-HOLE TRACE 1 and 2 (PC trace shorts 1 and 2) Short 2 and 3 (Cut open trace across pin holes 1 and 2) INC PIN Connected to VBATT OPERATING MODE VBATT voltage source feeds core input VMAIN voltage source feeds core input
Evaluating High Input Voltage Operation
Core Input
The MAX1775 EV kit is factory-set for both step-down switching regulators, deriving their power from the input voltage (VBATT). The input to the core regulator is limited to +5V. A cascaded configuration must be used for input voltages greater than +5V. (The core converter derives its power from the main output voltage.) To configure the MAX1775 EV kit cascaded, cut open the PC board trace, shorting pinholes 1 and 2 at jumper JU3. Place a short (soldered jumper wire) across pinholes 2 and 3 at jumper JU3. Consult Table 3 for input voltage jumper selection.
Evaluates: MAX1775
Connected to VMAIN (core cascaded)
Evaluating Other Output Voltages
MAIN Output
The MAX1775 EV kit's step-down switching regulator main output (VMAIN) is set to +3.3V by feedback resistors (R4, R5). To generate output voltages other than +3.3V (+2.5V to +5V), select different voltage-divider resistors (R4, R5). Refer to the Setting the Output Voltages section in the MAX1775 data sheet for instructions on selecting the resistors.
CORE Output
The MAX1775 EV kit's step-down switching regulator core output (VCORE) is set to +1.8V by feedback resistors (R1, R2). To generate output voltages other than +1.8V (+1V to +5V), select different voltage-divider resistors (R1, R2). Refer to the Setting the Output Voltages section in the MAX1775 data sheet for instructions on selecting the resistors.
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3
Evaluates: MAX1775
MAX1775 Evaluation Kit
Figure 1. MAX1775 EV Kit Schematic
4
VBATT
6
VBATT
+2.7V TO +5.5V
GND C2 1F
8
C1 10F 25V
IN PDRV
L1 5.0H
7
P1-B
C8 10F 6.3V
CS+
VMAIN VMAIN +3.3V
CVH
5
CVL
4
VBATT
C5 1F NDRV
1 SHDNM
P1-A
D1 OPEN
SHDNM
R3 33m 1% 0.5W
C3 47F 6.3V
GND
1 2
JU1 CS+ 11 U1 CSVBATT MAX1775
INC 1 15 12
3
CVL SHDNC 1 2
JU2
2 SHDNC REF 2 3 9
JU3 C7 10F 6.3V L2 5.4H
CS+ 3
1
JU4
C9 OPEN LXC 10 FBM FBC 13 R5 40.2k R4 66.5k 1% 16
2
3
C6 0.22F
VMAIN VCORE +1.8V R1 24.3k 1% C4 47F 6.3V GND
VMAIN
C10 OPEN
GND
14 3
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PGND R2 30.1k 1%
MAX1775 Evaluation Kit Evaluates: MAX1775
1.0"
1.0"
Figure 2. MAX1775 EV Kit Component Placement Guide-- Component Side
Figure 3. MAX1775 EV Kit PC Board Layout--Component Side
1.0"
Figure 4. MAX1775 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.
5 _____________________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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