SW

Ramp

Generator

Oscillator

Current

Sensor

OLP

CTRL

GND

C3

L1

+

FB

Reference

Control

D1

Error

Amplifer

2

1

Rset

C2

Vin

C1

PWM Control

4

6

Soft

Start-up

5

3

COMP

11

TPS61160, TPS61161

www.ti.com

SLVS791E – NOVEMBER 2007 – REVISED JULY 2016

Product Folder Links: TPS61160 TPS61161

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Copyright © 2007–2016, Texas Instruments Incorporated

7 Detailed Description

7.1 Overview

The TPS61160 and TPS61161 are high-efficiency, high-output voltage boost converters in a small package size.

These devices are ideal for driving white LED in series. The serial LED connection provides even illumination by

sourcing the same output current through all LEDs, eliminating the need for expensive factory calibration. Each

device integrate a 40-V, 0.7-A switch FET and operatea in pulse width modulation (PWM) with 600-kHz fixed

switching frequency. For operation see the block diagram. The duty cycle of the converter is set by the error

amplifier output and the current signal applied to the PWM control comparator. The control architecture is based

on traditional current-mode control; therefore, a slope compensation is added to the current signal to allow stable

operation for duty cycles larger than 50%. The feedback loop regulates the FB pin to a low reference voltage

(200 mV typical), reducing the power dissipation in the current sense resistor.

7.2 Functional Block Diagram

7.3 Feature Description

7.3.1 Soft Start-Up

Soft-start circuitry is integrated into the device to avoid a high inrush current during start-up. After the device is

enabled, the voltage at FB pin ramps up to the reference voltage in 32 steps with each step taking 213 μs. This

ensures that the output voltage rises slowly to reduce the input current. Additionally, for the first 5 msec after the

COMP voltage ramps, the current limit of the switch is set to half of the normal current limit spec. During this

period, the input current is kept below 400 mA (typical). See the start-up waveform of a typical example,

Figure 10.