TQL850CSV33

Taiwan Semiconductor

6

Version: B2207

APPLICATION INFORMATION

TQL850CSV33 is a high-performance low dropout voltage regulator. The device operates with a wide input voltage

from 3V to 50V and up to 500mA of output current. It also provides a high accuracy output voltage for ±2% in all the

load and line regulation.

Reset

The TQL850CSV33 is monitored by Reset system including Power-ON Delayed Reset, Under-Voltage Reset, and

Reset Threshold Adjustment. When reset is activated, the RO/WDO pin is low.

◼ Power-ON Delayed Reset

When device starts up, the RO/WDO pin delays to become “High” in Power-ON Delayed Time (tRD) without

reset issue.

◼ Under-Voltage Reset

When the output supply voltage drops below UVLO Reset Lower Threshold (VRTL), the RO/WDO switches from

“High” to “Low”. The RO/WDO pin is an open collector output with an internal pull-up resistor.

◼ Reset Threshold Adjustment

The UVLO Reset Lower Threshold can be adjusted. If the RTH pin connects to GND, the threshold voltage is

default value (VRTL). We can take two resistors (Rth1, Rth2) to adjust under-voltage threshold. The Rth1 is

connected between OUT pin and RTH pin and Rth2 is connected between RTH and GND. The reminder is

taking proper resistance for current sourcing. The new threshold voltage is calculated as follows:

VRTL,new = VRTTH x (Rth1 + Rth2) / Rth2

●

VRTL,new : Desired switching threshold

●

Rth1, Rth2 : External divider resistors

●

VRTTH : Reset adjust switching threshold

Watchdog

The TQL850CSV33 has the watchdog function with fixed watchdog timing to monitor microcontroller process. The

device monitors the period clock-pulse provided by Microcontroller at WDI pin in a certain timing (Watchdog Trigger

Time, tWDI,tr). If

there is no signal in Watchdog Trigger Time, the RO/WDO pin becomes “Low” in a certain time

(Watchdog Low Time, tWDOL

). After that, the RO/WDO pin returns to “High” and keep watching the WDI signal

repeatedly. The RO/WDO pin is an open collector output with an internal pull-up resistor.

The Watchdog function is inactivated by WDI pin. While the WDI voltage is in 1.15V to 1.4V, the Watchdog function

is disable.

Typical Watchdog Timing Diagram, Watchdog and Reset Modes

Ignore Time

Don’t care W I

during t

rd

and ignoret im e

tWDOL

t

WI,I

Trigger

V

WI

WD Trigger

t

V

RO/WDO

t

Normal operation

t

V

I

V

OUT

V

RTH

t

t

RR

48ms *)

NO WDTrigger

48ms *)

WD Trigger

48ms *)

WD Trigger

Normal operation

V

RTL

Don’t care W DI

during t

WDO,low

and

ignore time

t

48ms *)

48ms *)

48ms *)

WD Trigger

WD Trigger

WD Trigger

t

RD

Ignore Time

tWDI,i

Don’t care WDI

t

RD

and ignore time

Power

Fail

t

RD