Datasheet

TPS51220A

SLUS897E –DECEMBER 2008–REVISED JANUARY 2013

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OVERVOLTAGE/UNDERVOLTAGE PROTECTION

TPS51220A monitors the output voltage to detect overvoltage and undervoltage. When the output voltage

becomes 15% higher than the target value, the OVP comparator output goes high and the circuit latches as the

high-side MOSFET driver OFF and the low-side MOSFET driver ON, and shuts off another channel.

When the feedback voltage becomes lower than 70% of the target voltage, the UVP comparator output goes

high and an internal UVP delay counter begins counting. After 1 ms, TPS51220A latches OFF both high-side and

low-side MOSFETs, and shuts off another channel. This UVP function is enabled after soft-start has completed.

OVP function can be disabled as shown in Table 4. The procedures for restarting from these protection states

are:

1. toggle EN

2. toggle EN1 and EN2 or

3. once hit UVLO

Table 4. FUNC Logic States

FUNC GND VREF2 VREG3 VREG5

OVP Enable Disable Enable Disable

CONTROL Current mode D-CAP mode D-CAP mode Current mode

SCHEME

UVLO PROTECTION

The TPS51220A has undervoltage lockout protections (UVLO) for VREG5, VREG3 and VREF2. When the

voltage is lower than UVLO threshold voltage, TPS51220A shuts off each output as shown inTable 5. This is

non-latch protection.

Table 5. UVLO Protection

CH1/ CH2 VREG5 VREG3 VREF2

VREG5 UVLO Off — On On

VREG3 UVLO Off Off — Off

VREF2 UVLO Off Off On —

THERMAL SHUTDOWN

The TPS51220A monitors the device temperature. If the temperature exceeds the threshold value, TPS51220A

shuts off both SMPS and 5V-LDO, and decreases the VREG3 current limitation to 5 mA (typically). This is non-

latch protection.

Product Folder Links :TPS51220A