TS823_09 datasheet, PDF - EEWORLD Datasheet

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TS823_09: DescriptionMicroprocessor Supervisory Circuit with Watchdog Timer & Manual Reset; File Size173KB，8 Pages; ManufacturerTaiwan Semiconductor; Websitehttp://www.taiwansemi.com/

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TS823_09 Overview

Microprocessor Supervisory Circuit with Watchdog Timer & Manual Reset

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TS823/824/825 Series

Microprocessor Supervisory Circuit

with Watchdog Timer & Manual Reset

SOT-25

General Description

The TS823/824/825 family allows the user to customize the CPU monitoring function without any external

components. The user has a large choice of reset voltage thresholds and output driver configurations, all of which are

present ant the factory. Each wafer is trimmed to the customer’s specifications.

These circuits will ignore fast negative going transients on Vdd. The state of the reset output is guaranteed to be

correct down to 1V. After Vdd crosses above a factory present threshold, the TS823/824/825 assert a reset signal.

After a predetermined time (the “reset” interval) the reset is deasserted. If Vdd ever drops below the threshold voltage

a reset is asserted immediately. In addition to a supply monitoring function the TS823/824/825 also monitor transitions

at the watchdog (WDI) input. If a logic transition does not occur at the WDI pin within a certain time interval (the

“watchdog” interval) then a reset is asserted. The reset deasserts after the reset interval, as explained earlier.

The TS823/824/825 can both assert a reset manually by pulling the MR input to ground, and the micro-power

quiescent current make this family a natural for portable battery powered equipment.

Features

●

Precision monitoring of +3V, +3.3V and +5V power

supply voltage

Tight voltage threshold tolerance +/-1.5%

Fully specified over temperature

210mS min. power-on reset pulse width

3uA(typ) supply current

Guaranteed reset valid to Vdd = +1V

Power supply transient immunity

No external components

Ordering Information

Part No.

Package

Packing

TS823CX5x RF

SOT-25

3Kpcs / 7” Reel

TS824CX5x RF

SOT-25

3Kpcs / 7” Reel

TS825CX5x RF

SOT-25

3Kpcs / 7” Reel

Note:

is the threshold voltage type, option as

: 4.63V

: 4.38V

: 3.08V

: 2.93V

: 2.63V

: 2.32V

: 2.19V

Contact factory for additional voltage option

Pin Descriptions

Function

RESET (Active-Low)

Ground

Manual Reset

(RESET) (Active-High)

Watchdog Input

Supply Voltage (Vdd)

Applications

●

Computers and Controllers

Embedded Controllers

Intelligent instruments

Critical uP monitoring

Portable / Battery powered equipment

Automotive Systems

TS823

TS824

TS825

Absolute Maximum Rating

Parameter

Supply Voltage

Supply Voltage - Recommended

Operating Junction Temperature Range

Storage Temperature Range

Thermal Resistance

Symbol

Vdd

STG

Θjc

Maximum

6.0

0.9 ~ 5

-40 ~ +125

-65 ~ +150

256

Unit

C/W

Maximum Lead Temperature (260 C)

LEAD

Notes: Stress above the listed absolute rating may cause permanent damage to the device.

1/8

Version: C07

TS823/824/825 Series

Microprocessor Supervisory Circuit

with Watchdog Timer & Manual Reset

Application Information

The TS823/824/825 are designed to interface with the reset input of a microprocessor and to prevent CPU execution

errors due to power up, power down, and other power supply errors. The TS823/824 also monitor the CPU health by

checking for signal transitions form the CPU at the WDI input.

Reset Output

Active low reset outputs are denoted as RESET, Active high reset output are denoted as (RESET),

A reset will be asserted if any of three things happen:

1. Vdd drops below the threshold (Vth)

2. The MR pin is pulled low.

3. The WDI pin does not detect a transition within the Watch Dog interval (TWD)

The reset will remain asserted for the prescribed reset interval after:

1. Vdd rises above the threshold (Vth)

2. MR goes high

3. The Watch Dog timer have timed out causing the reset to assert.

Manual Reset Input

The TS823 and TS825 feature a manual reset feature (MR). A logic low on the MR pin asserts a reset. The reset

remains asserted a long as the MR pin remains low. After the MR pin transitions to a high state the reset remains

asserted for the prescribed reset interval (TD2). The MR pin is internally pulled up to Vdd by a 100KΩ resistor. It is

internally de-bounced to reject switching transients.

The MR pin is ESD protected by diodes connected to Vdd and Gnd. So the MR pin should never be driven higher than

Vdd or lower than Gnd.

Watchdog Input

The TS823 and TS824 are equipped with a watchdog input (WDI). If the microprocessor does not produce a valid logic

edge at the watchdog input (WDI) within the prescribed watchdog interval (TWD) then a reset asserts. The reset

remains asserted for the required reset interval (TD2). Ata the end of the reset interval the reset is deasserted and the

watchdog interval timer starts again from zero.

If the watchdog input is left unconnected or is connected to a tri-stated buffer the watchdog function is disabled. As

soon as the WDI input is driven either low or high the watchdog function resumes with the watchdog timer set to zero.

Watchdog Input Current

The watchdog input pin (WDI) typically sources/sinks 8uA when driven high or low. So from a power dissipation point

of view the duty cycle of the waveform at WDI is unimportant. When the WDI pin is floating or tri-stated the power

supply current fall to less than 3uA.

Glitch Rejection

The TS823/824/825 family will reject negative going transients on the Vdd line to some extent. The smaller the

duration of the transient the larger its amplitude may be without triggering a reset. The “Glitch Rejection” chart in the

graphs section of this datasheet shows the relation between glitch amplitude and allowable glitch duration to avoid

unintended resets.

Accurate Output State at Low Vdd

With Vdd voltage on the order of the MOS transistor threshold (<1V) the outputs of the TS823/824/825 may become

undefined. For parts with active low output RESET a resistor placed between RESET and Gnd on the order of 100KΩ

will ensure that the RESET output stays low when Vdd is lower than the threshold voltage of the part. In a like manner

a resistor on the order of 100KΩ when placed between (RESET) and Vdd will ensure parts with active high output

(RESET) will remain high when Vdd is lower than the threshold voltage of the parts.

3/8

Version: C07

TS823_09 Related Products

	TS823_09	TS823CX5RF	TS825CX5RF	TS824CX5RF
Description	Microprocessor Supervisory Circuit with Watchdog Timer & Manual Reset	Microprocessor Supervisory Circuit with Watchdog Timer & Manual Reset	Microprocessor Supervisory Circuit with Watchdog Timer & Manual Reset	Microprocessor Supervisory Circuit with Watchdog Timer & Manual Reset

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