Datasheet

TPS2458
SLUS916B –FEBRUARY 2009–REVISED MAY 2010 www.ti.com
TERMINAL FUNCTIONS (continued)
2
3
10
GND 25 — Ground connections.
27
29
31
IN3 17 I 3-V input. Supply pin for the 3-V channel internal pass FET.
IN12 16 I 12-V input. Supply pin for 12-V channel internal circuitry.
12-V blocking transistor enable. (active low). Pulling this pin low allows the 12-V channel ORing function to
OREN 11 I operate normally. Pulling this pin high (or allowing it to float high) disables the 12-V ORing function by pulling
the BLK pin low. An internal 200-kΩ resistor pulls this pin up to VINT when disconnected.
OUT12 9 I/O 12-V output. Senses the output voltage of the 12-V channel.
OUT3 18 I/O 3-V output. Output of the 3-V channel internal pass FET.
12-V pass transistor gate drive. This pin sources 30 mA to turn the FET on. An internal clamp prevents this pin
PASS 12 O
from rising more than 14.5 V above IN12.
12-V power good output,asserts when V
OUT12
> V
PG12
( active low) . Open-drain output indicating that
PG12 4 O
channel 12 output voltage has dropped below the PG threshold, which nominally equals 10.5 V.
3-V power good output, asserts when V
OUT3
> 2.8 V ( active low) . Open-drain output indicating that channel 3
PG3 21 O
output voltage has dropped below the PG threshold, which nominally equals 2.85 V.
SENM 13 I 12-V current limit sense. Senses the voltage on the low side of the 12-V channel current sense resistor.
SENP 15 I 12-V input sense. Senses the voltage on the high side of the 12-V channel current sense resistor.
12-V current limit set. A resistor connected from this pin to SENP sets the current limit level in conjunction with
SET 14 I the current sense resistor and the resistor connected to the SUM12 pin, as described in 12-V thresholds,
setting current limit and fast overcurrent trip section.
12 V summing node. A resistor connected from this pin to ground forms part of the channel x current limit. As
SUM12 5 I/O the current delivered to the load increases, so does the voltage on this pin. When the voltage on this pin
reaches 675 mV, the current limit amplifier acts to prevent the current from further increasing.
3 V summing node. A resistor connected from this pin to ground forms part of the channel x current limit. As
SUM3 22 I/O the current delivered to the load increases, so does the voltage on this pin. When the voltage on this pin
reaches 675 mV, the current limit amplifier acts to prevent the current from further increasing.
VDD3 23 I 3-V charge pump input
Bypass capacitor connection point for internal supply. This pin connects to the internal 2.35-V rail. A 0.1-mF
VINT 1 I/O capacitor must be connected from this pin to ground. Do not connect other external circuitry to this pin
except the address programming pins, as required.
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