LR6301 datasheet(8/22 Pages) LRC

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Leshan Radio Co ., Ltd

8/22

OPERATING DESCRIPTION FOR DELAY CD

The LR6301 with SOT23-5 series devices consist of

precision voltage detector that drives a time delay generator.

Figures 37 and 38 show a timing diagram and a typical

application. Initially consider that input voltage Vin is at a

nominal level and it is greater than the voltage detector upper

threshold (VDET+). The voltage at Pin 5 and capacitor CD

will be at the same level as Vin, and the reset output (Pin 1)

will be in the high state for active low devices, or in the low

state for active high devices. If there is a power interruption

and Vin becomes significantly deficient, it will fall below the

lower detector threshold (VDET−) and the external time

delay capacitor CD will be immediately discharged by an

internal N−Channel MOSFET that connects to Pin 5. This

sequence of events causes the Reset output to be in the low

state for active low devices, or in the high state for active

high devices. After completion of the power interruption,

Vin will again return to its nominal level and become greater

than the VDET+. The voltage detector will turn off the

N−Channel MOSFET and allow pullup resistor RD to charge

external capacitor CD, thus creating a programmable delay

for releasing the reset signal. When the voltage at Pin 5

exceeds the inverter/buffer threshold, typically 0.675 Vin,

the reset output will revert back to its original state. The

voltage detector and inverter/buffer have built-in hysteresis

to prevent erratic reset operation.

Although these device series are specifically designed for

use as reset controllers in portable microprocessor based

systems, they offer a cost−effective solution in numerous

applications where precise voltage monitoring and time

delay are required.

Timing Waveforms

tD2

Vin

VDET+

VDET−

Input Voltage, Pin 2

Capacitor, Pin 5

Vin

0 V

Reset Output (Active Low), Pin 1

Vin

Reset Output (Active High), Pin 1

Vin

0 V

0.675 Vin

VDET−

Ver 1.5 Nov 2009

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