Datasheet

VIN
VOUT
VIN-UVLO
5V or 3.3V
Tracking
0
0
TPS7A6533-Q1
TPS7A6550-Q1
www.ti.com SLVSA98C –MAY 2010–REVISED JULY 2012
Undervoltage Shutdown Integrated Fault Protection
These devices have an integrated undervoltage These devices feature integrated fault protection to
lockout (UVLO) circuit to shut down the output if the make them ideal for use in automotive applications.
input voltage (V
IN
) falls below an internally fixed In order to keep them in a safe area of operation
UVLO threshold level (V
IN-UVLO
) as shown in Figure 7. during certain fault conditions, they use internal
This ensures that the regulator does not latch into an current-limit protection and current-limit foldback to
unknown state during low input-voltage conditions. limit the maximum output current. This protects them
The regulator normally powers up when the input from excessive power dissipation. For example,
voltage exceeds the V
IN(POWERUP)
threshold. during a short-circuit condition on the output; limiting
current through the pass element to I
CL
protects the
device from excessive power dissipation.
Low-Voltage Tracking
At low input voltages, the regulator drops out of
Thermal Shutdown
regulation, and the output voltage tracks input minus
a voltage based on the load current (I
OUT
) and switch These devices incorporate a thermal shutdown (TSD)
resistance (R
SW
) as shown in Figure 7. This allows for circuit as a protection from overheating. For
a smaller input capacitor and can possibly eliminate continuous normal operation, the junction
the need of using a boost convertor during cold crank temperature should not exceed the TSD trip point. If
conditions. the junction temperature exceeds the TSD trip point,
the output turns off. When the junction temperature
falls below the TSD trip point, the output turns on
again. Figure 8 shows this.
Figure 7. Undervoltage Shutdown and Low-
Voltage Tracking
Figure 8. Thermal Cycling Waveform for
TPS7A6550-Q1 (V
IN
= 24 V, I
OUT
= 300 mA, V
OUT
= 5
V)
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