DETAILED DESCRIPTION

-470.02

R(RSET)

V

- 0.00314

(OFF)

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TPS2410

TPS2411

SLVS727B – NOVEMBER 2006 – REVISED FEBRUARY 2007

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

threshold.

Several internal comparator and amplifier circuits monitor these two pins. 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 A. Protect the internal circuits with an external clamp if C can be more than 6 V lower

than A. A small signal clamp diode and 1-k

Ω resistor, or circuit per Figure 18 are suitable.

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 due to this topology. The A and C pins should be

Kelvin connected to the MOSFET source and drain. A and C connections should also be short and low

impedance, with special attention to the A connection. Residual noise from the charge pump can be reduced

with a bypass capacitor at A if the application permits.

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 TPS2410/11.

FLTR: The internal fast comparator input may be filtered by placing a small capacitor from FLTR to A. This is

will suppress small transients, large voltage reversals will see relatively small additional turn-off delay.

FLTR is clamped to C and should only be used with a capacitor as shown in Figure 14. Connections to FLTR

should be short and direct to minimize parasitic capacitive loading and crosstalk. The filter pin may not be

shorted to any other voltage.

FLTB: The FLTB pin is the open-drain fault output. FLTB sinks current when the MOSFET should be enabled,

satisfied. FLTB has a 3-ms deglitch filter on the falling edge to prevent transients from creating false signals.

GATE: Gate connects to 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 fast 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.

RSET: A resistor connected from this pin to GND sets the MOSFET fast turn-off comparator threshold. The

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

voltage to increasing negative values. The TPS2411 must have a negative threshold programmed to avoid an

follows.

The units of the numerator are (V

× V/A). V

RSVD: Connect to ground.

7

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