MB3793-34A Datasheet, PDF (5/26 Pages) Cypress Semiconductor – Precise detection of power voltage fall: 2.5%

MB3793-34A
4. Block Functions
1. Comp.S
Comp.S is a comparator with hysteresis to compare the reference voltage with a voltage (VS) that is the result of dividing the power
voltage (VCC) by resistors R₁ and R₂. When VS falls below 1.24 V, a reset signal is output. This function enables the MB3793 to
detect an abnormality within 1 s when the power is cut or falls abruptly.
2. Output circuit
The output circuit has a comparator to control the reset signal (RESET) output. When the voltage at the CTP pin for setting the
power-on reset hold time exceeds the threshold voltage, resetting is canceled.
Since the reset (RESET) output buffer has the CMOS organization, no pull-up resistor is needed.
3. Pulse generator
The pulse generator generates pulses when the voltage at the CK1 and CK2 input clock pins changes from Low level to High level
(positive-edge trigger) and exceeds the threshold voltage; it sends the clock signal to the watchdog timer.
4. Watchdog timer
The watchdog timer can monitor two clock pulses. Short-circuit the CK1 and CK2 clock pins to monitor a single clock pulse.
5. Logic circuit
Logic circuit controls charging and discharging of the power-on reset hold time setting capacity (C_TP) on a signal of Comp.S and
Watchdog timer.
Document Number: 002-08556 Rev. *A
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