-470.02

R(RSET)

V

- 0.00314

(OFF)

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TPS2419

SLVS998A – FEBRUARY 2010 – REVISED MARCH 2010

www.ti.com

DETAILED DESCRIPTION

The following descriptions refer to the pinout and the functional block diagram.

(see RSET). These two thresholds serve as a hysteretic GATE control with the ON/OFF state preserved until the

next (opposite) threshold cross.

The internal charge pump output, which provides bias power to the comparators and voltage to drive GATE, is

referenced to A. Some charge pump current appears on A.

C is both the cathode voltage sense and the bias supply for the gate-drive charge pump and other internal

circuits. This pin must be connected a source that is 3 V or greater when the external MOSFET is to be turned

on.

A 0.01-mF minimum bypass capacitor to GND is recommended for both A and C inputs. A and C connections to

the bypass capacitor and the controlled MOSFET should be short and low impedance.

The inputs are protected from excess differential voltage by a clamp diode and series resistance. If C falls below

A by more than about 0.7 V, a small current flows out of C. Configurations which permit C to be more than 6 V

lower than A should be avoided.

BYP: BYP is the internal charge pump output, and the positive supply voltage for internal comparator circuits and

GATE driver. A capacitor must be connected from BYP to A. While the capacitor value is not critical, a 2200-pF

ceramic is recommended. Traces to this part must be kept short and low impedance to provide adequate filtering.

Shorting this pin to a voltage below A damages the TPS2419.

EN: A voltage greater than 1.3 V on EN permits the TPS2419 to operate in its normal ORing mode. A voltage

below the lower threshold forces GATE to remain low, however EN going high will not automatically turn GATE

ON. EN going low when GATE is high engages the sustain current pulldown. EN should not be driven higher

than its recommended maximum voltage.

GATE: Gate controls the external N channel MOSFET gate. GATE is driven positive with respect to A by a driver

operating from the voltage on BYP. A time-limited high current discharge source pulls GATE to GND when the

turn-off comparator is activated. The high-current discharge is followed by a sustaining pull-down. The turn-off

circuits are disabled by the thermal shutdown, leaving a resistive pull-down to keep the gate from floating. The

gate connection should be kept low impedance to maximize turn-off current.

GND: This is the input supply reference. GND should have a low impedance connection to the ground plane. It

carries several Amperes of rapid-rising discharge current when the external MOSFET is turned off, and also

carries significant charge pump currents.

slightly positive when the RSET pin is left open. Current drawn by the resistor programs the turn-off voltage to

increasing negative values. The TPS2419 must have a negative threshold programmed to avoid an unstable

(1)

RSVD: Connect to ground.

6

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Product Folder Link(s): TPS2419