Introduction

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1

Introduction

The TPS62090 device family is a high-frequency synchronous step down converter optimized for small

solution size, high efficiency and is suitable for battery-powered applications. To maximize efficiency, the

converter operates in PWM mode with a nominal switching frequency of 2.8 MHz/1.4 MHz and

automatically enters Power Save Mode operation at light-load currents. When used in distributed power

supplies and point-of-load regulation, the device allows voltage tracking to other voltage rails and tolerates

capacitors ranging from 22 µF up to 100 µF. Using the DCS Control™ topology, the device achieves

excellent load transient performance and accurate output voltage regulation. The device is available in 3 x

3-mm, 16-pin package with thermal pad.

2

Considerations When Evaluating the TPS62090

The TPS62090 can be programmed for a switching frequency of 2.8 MHz/1.4 MHz by JP2. The higher

switching frequency reduces the ripple current and voltage. If the LC filter is adjusted, note that the

inductor minimum value is 1 µH for the 1.4-MHz setting and 0.47 µH for the 2.8-MHz setting. The EVM

was built with a 1-µH inductor and a 22-µF output capacitor. The integrated circuit (IC) has a two- stage

input current limit that sets the initial current limit to one third (approximately 1.55 A) of the normal peak

current limit of approximately 4.6 A, when the output is less than 0.6 V. Most system loads do not become

enabled or active until the output has reached 0.8 V, which is after the initial start-up current limit. If a low-

resistance load is used (less than approximately 1

Ω), the part can get stuck in short-circuit mode during

power up. Thus, very heavy loads may have to be applied after power up or the user can place an N-CH

logic level FET in series with the resistor (drain connected to ground side of resistor, source connected to

ground and gate tied to the drain). Once the output reaches approximately 1 V, the load turns on.

3

Test Summary

The TPS62090EVM-063 board requires an adjustable dc power supply with up to a 6-V output and

≥ 2.5

A for powering the input to the EVM and a resistive output load between 1 k

Ω and 0.6 Ω. Choose the

proper power rating for the load resistor, P = V

test setup connections and jumper settings selections are configured for a stand-alone evaluation, but can

be changed to interface with external hardware such as a system load and microcontroller.

3.1

Equipment

•

Adjustable dc power supply between 2.5 V and 6 V with adjustable current limit set to approximately

2.5 A

•

Load: System load, resistive load of 2

Ω, 3 W, and 25 Ω

•

Three Fluke 75 digital multimeters (DMM); (equivalent or better)

•

Oscilloscope, model TDS222 (equivalent or better)

3.2

Equipment and EVM Setup

Table 1 shows the setup input/output connections and configuration of the TPS62090 evaluation module.

The silk screen labels appear in parentheses.

Table 1. Setup I/O Connections and Configuration for TPS62090EVM Evaluation

Jack/Component (Silk Screen)

Connect or Adjustment to:

J1-1/2 (Vin)

P/S positive lead, preset to 4.5 Vdc; 2.5-A Current Limit

J2-1 (+ SNS);

Input Positive lead of DMM #1

J2-2 (– SNS);

Input Negative lead of DMM #1

J3-1/2 (GND)

P/S negative lead.

J5-1/2 (Vout)

Positive lead to system load or load resistance

J6-1 (+ SNS);

Output Positive lead of DMM #2

J6-2 (– SNS);

Output Negative lead of DMM #2

J7-1/2 (GND)

Negative lead to system load or load resistance

J4-1 (PG)

Positive lead of DMM #3

DCS Control is a trademark of Texas Instruments.

2

TPS62090EVM-063 Evaluation Module

SLVU670A – March 2012 – Revised May 2012

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