TC1271ARCVRC View Datasheet(PDF) - Microchip Technology

Part Name

Description

Manufacturer

TC1271ARCVRC

Voltage Supervisor with Manual Reset Input

Microchip Technology 

TC1270A/70AN/71A

VDD

Comparator

+

–

Reference

Voltage

Output

Driver

(Push-

Pull)

Delay

RST

MR

Noise Filter

FIGURE 4-4:

TC1270A Block Diagram.

VDD

Comparator

+

–

Reference

Voltage

Output

Driver

(Open-

Drain)

Delay

RST

MR

Noise Filter

VSS

FIGURE 4-5:

TC1270AN Block Diagram.

VDD

Comparator

+

–

Reference

Voltage

Output

Driver

(Push-

Pull)

Delay

RST

MR

Noise Filter

FIGURE 4-6:

TC1271A Block Diagram.

4.2 Voltage Detect Circuit

The Voltage Detect Circuit monitors VDD. The device’s

Reset voltage trip point (VTRIP) is selected when the

device is ordered. The voltage on the device’s VDD pin

determines the output state of the RST/RST pin.

VDD voltages above the VTRIP(MAX) force the RST/RST

pin inactive. VDD voltages below the VTRIP(MIN) force

the RST/RST pin active. The state of the RST/RST pin

is unknown for VDD voltages between VTRIP(MAX) and

VTRIP(MIN). This is shown in Table 4-1

TABLE 4-1: VDD LEVELS TO RST/RST

OUTPUT STATES

VDD Voltage Level

Output State

RST

RST

VDD ≥ VTRIP(MAX)

H (1, 2)

L (1)

VTRIP(MIN) < VDD < VTRIP(MAX)

U

U

VDD ≤ VTRIP(MIN)

L

H

Legend: H = Driven High

L = Driven Low

U = Unknown, driven either High or Low

Note 1: The RST/RST pin will be driven inactive

after the Reset Delay Timer (tRST) times

out.

2: The TC1270AN RST pin will be floated

after the Reset Delay Timer (tRST) times

out.

The term VTRIP will be used as the general term for the

trip point voltage where the device actually trips.

In the case where VDD is falling (for voltages starting

above VTRIP(MAX)):

• Voltages above VTRIP(MAX) will never cause the

RST/RST output pin to be driven Active.

• Voltages below VTRIP(MIN) will always cause the

RST/RST output pin to be driven Active.

Now in the case where VDD is rising (for voltages

starting below VTRIP(MIN)):

• Voltages above VTRIP(MAX) will always cause the

RST/RST output pin to be driven Inactive, (or

floated - TC1270AN) after the Reset Delay Timer

(tRST), times out.

DS22035B-page 18

© 2007 Microchip Technology Inc.

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