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

9

TPS61160A, TPS61161A

www.ti.com

SLVS937C – MARCH 2009 – REVISED JULY 2016

Product Folder Links: TPS61160A TPS61161A

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7 Detailed Description

7.1 Overview

The TPS61160A/61A is a high-efficiency, high output voltage boost converter in small package size that is 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. The device integrates 40-

V/0.7-A switch FET and operates 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 IC 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, each step takes 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 9.