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19-1861; Rev 0; 11/00
MAX889S Evaluation Kit
General Description
The MAX889 IC is an inverting charge pump that delivers a regulated negative output voltage at loads up to 200mA. The device operates from an input of +2.7V to +5.5V to produce a user-adjustable, regulated output of -2.5V to -VIN. The MAX889S evaluation kit (EV kit) is a fully assembled and tested surface-mount board. The board is set up to provide a -3.3V output from a +5.0V input supply. The EV kit is shipped with a MAX889S (1MHz switching frequency) installed. The board may also be used to evaluate the MAX889R (500kHz) or the MAX889T (2MHz). To do so, request a free sample of the MAX889RESA or MAX889TESA, and refer to the MAX889 data sheet for the appropriate capacitor values. o +2.7V to +5.5V Input Range o Uses One 2.2F and Two 10F Ceramic Capacitors o Output Adjustable from -2.5V to -VIN o 200mA Output Current o 1MHz Switching Frequency o Fully Assembled and Tested Surface-Mount Board
Features
Evaluates: MAX889
Component List
DESIGNATION QTY DESCRIPTION 10F, 6.3V X5R ceramic capacitors Taiyo Yuden JMK316BJ106ML Murata GRM42-6X5R106K6.3 2.2F, 10V X5R ceramic capacitor Taiyo Yuden LMK212BJ225MG 3-pin jumper 2-pin jumpers 49.9k 1% resistor 33.2k 1% resistor MAX889SESA MAX889S EV kit data sheet MAX889 IC data sheet Shunts PART MAX889SEVKIT C1, C3 2
Ordering Information
TEMP. RANGE 0C to +70C IC PACKAGE 8 SO
Quick Start
The MAX889S EV kit is fully assembled and tested. Follow the steps below to verify board operation. Do not turn on the power supply until all connections are completed: 1) Connect a voltmeter and the load to the VOUT pad. 2) Place the shunts in the following positions: JU1 1-2, JU2 closed, JU3 closed. 3) Connect a +5.0V supply to the pad labeled VIN. Connect the ground lead to the pad labeled GND. 4) Turn on the power and verify that the output is 3.3V.
C2 JU1 JU2, JU3 R1 R2 U1 None None None
1 1 2 1 1 1 1 1 3
Component Suppliers
SUPPLIER Murata Taiyo Yuden PHONE 814-237-1431 408-573-4150 FAX 814-238-0490 408-573-4159
Note: Please indicate that you are using the MAX889S when contacting these suppliers. ________________________________________________________________ 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.
MAX889S Evaluation Kit Evaluates: MAX889
Detailed Description
Jumper Selection
The MAX889 can be placed in shutdown mode, using jumper JU1. See Table 1 for jumper settings. Jumper JU2 connects VIN to the voltage-divider that sets the output voltage. To use a voltage source other than VIN as the reference, open JU2, and connect the reference source to the pad labeled VREF. The MAX889 can be placed into free-run mode (unregulated, VOUT = -VIN) by removing the shunt on JU3 and installing a shunt on JU2.
Capacitor Selection
Use capacitors with a low effective series resistance (ESR), such as ceramic or surface-mount chip tantalum types. Refer to the MAX889 data sheet for more information.
Table 1. Jumper Functions
JUMPER JUMPER POSITION 1-2* JU1 2-3 Open FUNCTION SHDN = High, MAX889 enabled SHDN = Low, MAX889 disabled Drive SHDN pad with an external signal Drive VREF pad with an external voltage to set the output voltage VIN is used to set the output voltage Used to place the MAX889 into free-run mode (JU2 must be closed) Output voltage is set by resistor-divider and VIN or VREF
Output Voltage Adjustment
The MAX889S EV kit is shipped with the resistor-divider selected for an output of -3.3V and an input of +5.0V. Output voltages other than -3.3V can be set one of two ways: 1) Change the resistor-divider formed by R1 and R2. Use the following equation to determine the resistor values: R2 = -(VOUT / VREF) R1 (The current through R1 and R2 should be at least 30A.) 2) Remove the shunt from JU2 and apply a voltage to the VREF pad. Use the following equation to determine the voltage for VREF: VREF = -(R1 / R2) VOUT *Default position
JU2 VIN GND 1 JU1 2 3 C1 10F
+
Open JU2 Closed*
Open JU3 Closed*
VREF R1 49.9k 1% FB 7
1 SHDN 6 IN SHDN
U1
2 C2 + 2.2F 4 CAPAGND 8 OUT GND 3 5 C3 10F GND
MAX889S
CAP+
R2 33.2k 1%
JU3 VOUT
+
Figure 1. MAX889S EV Kit Schematic Diagram 2 _______________________________________________________________________________________
MAX889S Evaluation Kit Evaluates: MAX889
Board dimensions: 2.4in by 1.4in
Board dimensions: 2.4in by 1.4in
Figure 2. MAX889S EV Kit Component Placement Guide-- Component Side
Figure 3. MAX889S EV Kit PC Board Layout--Component Side
Board dimensions: 2.4in by 1.4in
Figure 4. MAX889S 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.
Maxim Integrated Products, 120 San Gabriel Drive, Sunnyvale, CA 94086 408-737-7600 _____________________ 3 (c) 2000 Maxim Integrated Products Printed USA is a registered trademark of Maxim Integrated Products.

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