TL7700CMPWPSEP datasheet(11/25 Pages) TI1

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tpo

RESET

Vhys

VCC

1.5 V

Vs’

VCC

GND

RESET

VCC

RESET

GND

SENSE

TL7700-SEP

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SLVSF13 – MARCH 2019

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8.3 Feature Description

8.3.1 Sense-Voltage Setting

The SENSE terminal input voltage, Vs, of the TL7700-SEP typically is 500 mV. By using two external resistors,

the circuit designer can obtain any sense voltage over 500 mV. In Figure 18, the sensing voltage, Vs', is

calculated as:

Vs' = Vs × (R1 + R2) / R2

where

•

Vs = 490 mV to 520 mV over temperature range

(1)

Figure 18. Setting the Sense Voltage

8.3.2 Sense-Voltage Hysteresis Setting

If the sense voltage (Vs') does not have hysteresis in it and the voltage on the sensing line contains ripples, the

resetting of TL7700-SEP will be unstable. Hysteresis is added to the sense voltage to prevent such problems. As

shown in Figure 19, the hysteresis (Vhys) is added and the value is determined as:

Vhys = Is × R1

where

•

Is = 1.5 μA to 3.5 μA over temperature range

(2)

NOTE: The sense voltage, Vs', is different from the SENSE terminal input voltage, Vs. Vs normally is 500 mV for triggering.

Figure 19. VCC-RESET Timing Chart

TL7700CMPWPSEP Datasheet(PDF) 11 Page - Texas Instruments