SNVU297 – JULY 2013

Using the LMZ34002: Negative Output Voltage

Simple Switcher® Power Module Evaluation Module

1

Introduction

The LMZ34002EVM-001 Evaluation Module is designed as an easy-to-use platform that facilitates an

extensive evaluation of the features and performance of the Simple Switcher® power module. This guide

provides information on the correct usage of the EVM and an explanation of the numerous test points on

the board.

2

Description

The EVM features a LMZ34002 device configured for operation from a 4.5 V to 40 V input supply. The

LMZ34002 is a non-synchronous, buck-boost (negative output) converter optimized for output voltages

between -3 V and -17 V. The LMZ34002 operates at a fixed frequency of typically 800 kHz. The output

voltage can be set to one of four popular values by using a simple configuration jumper. The EVM can

supply up to 2 A of output current depending on the input and output voltage (See Figure 1). A minimal

amount of input and output capacitance is used on the board. Component pads are provided for additional

input and output capacitors if desired. Test points are provided that allow measurement of efficiency,

power dissipation, input ripple, output ripple, line and load regulation, soft-start behavior, transient

response, and UVLO behavior. The EVM uses a recommended PCB layout that maximizes thermal

performance and minimizes output ripple and noise.

3

Getting Started

The host power supply is connected to the EVM at terminal block TB1. The VIN and GND terminals are

clearly marked. The terminal block can accept up to number 16 AWG wire. For a complete evaluation, the

host supply should be adjustable up to 40 V and be capable of delivering at least 3 A of current. The

output of the EVM is presented to terminal block TB2. An electronic or resistive load can be connected to

the block.

Input and output voltage test points are provided near the terminal blocks. These test points are intended

to be used as voltage monitoring points where voltmeters can be connected to measure V

not use these test points as the input supply or output load connection points. The PCB traces connecting

to the test points are not designed to support high currents.

Before applying power, make certain that the V

for the intended output voltage. Always remove power before changing the jumper settings.

Once the jumper setting has been confirmed, set the host input supply to a voltage level between 4.5 V to

40 V, making sure that the sum of V

voltages for the four preset V

output voltage is obtained.

Table 1. Output Voltage Settings and Maximum V

IN

V

MAXIMUM V

-3.3

40

-5

40

-12

38

-15

35

1

SNVU297 – JULY 2013

Using the LMZ34002: Negative Output Voltage Simple Switcher® Power

Module Evaluation Module

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