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TPS61162D

SLVSC13A – JULY 2013 – REVISED MARCH 2016

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Copyright © 2013–2016, Texas Instruments Incorporated

Feature Description (continued)

8.3.6 Full-Scale Current Program

The dual channels of the TPS61162D can provide up to 30 mA current each — when either the EasyScale

interface or PWM interface is selected, the full-scale current (current when dimming duty cycle is 100%) of each

where

•

•

•

•

(1)

8.3.7 Brightness Control

The TPS61162D controls the DC current of the dual channels to realize the brightness dimming. The DC current

control is normally referred to as analog dimming mode. When the DC current of LED diode is reduced, the

brightness is dimmed.

The TPS61162D can receive either the PWM signals at the PWM pin (PWM interface) or digital commands at

the EN pin (EasyScale interface) for brightness dimming. If the EasyScale interface is selected, the PWM pin

must be kept high; if PWM interface is selected, the EN pin must be kept high.

8.3.8 Undervoltage Lockout

An undervoltage lockout circuit prevents the operation of the device at input voltages below undervoltage

threshold (2.2 V typical). When the input voltage is below the threshold, the device is shut down. If the input

voltage rises by undervoltage lockout hysteresis, the device restarts.

8.3.9 Overvoltage Protection

Overvoltage protection circuitry prevents device damage as the result of white LED string disconnection or

shortage.

The TPS61162D monitors the voltages at the SW and IFBx pins during each switching cycle. If either SW OVP

protection circuitry is triggered. Refer to Figure 6 and Figure 7 for the protection actions.

If one LED string is open, its IFBx pin voltage drops, and the boost output voltage is increased by the control

loop as it tries to regulate this lower IFBx voltage to the target value (90 mV typical). The current of the normally

operating string is properly regulated but its IFBx voltage rises because of the rise in output voltage. During this

If both LED strings are open, the voltages of both IFBx pins drop to ground, and the boost output voltage is

protection circuitry is triggered, and the device is latched off. Only the VIN POR pin or EN/PWM pin toggling can

restart the device.

One LED diode short in a string is allowed in the TPS61162D. If one LED diode in a string is short, the IFBx

voltage of the normal string is regulated to about 90 mV, and the IFBx pin voltage of the abnormal string is

higher. Typically with only one diode short, the higher IFBx pin voltage does not reach the IFBx OVP threshold

If more than one LED diodes are short in a string, as the boost loop regulates the IFBx normal string voltage to

circuitry is triggered.

SW OVP protection is also triggered when the forward voltage drop of an LED string exceeds the SW OVP

threshold. In this case, the device turns off the switch FET and shuts down.