MCP2122 Просмотр технического описания (PDF) - Microchip Technology

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MCP2122

Infrared Encoder/Decoder

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MCP2122

2.3.1 BROWN-OUTS

Some applications may subject the MCP2122 to a

brown-out condition. Good design practice requires

that when a system is in brown-out, the system should

be in reset to ensure that the system is in a known

state when the system exits the brown-out. This

brown-out circuitry is external to the MCP2122.

2.3.1.1 External Brown-Out Reset Circuits

Figure 2-2 shows a circuit for external brown-out

protection using the TCM809 device.

Figure 2-3 and Figure 2-4 illustrate two examples of

external circuitry that may be implemented. Each

option needs to be evaluated to determine if they

satisfy the requirements of the application.

FIGURE 2-2:

EXTERNAL BROWN-OUT

PROTECTION USING THE

TCM809

VDD

VDD

TCM809

RST

VSS

RESET

MCP2122

FIGURE 2-3:

EXTERNAL BROWN-OUT

PROTECTION CIRCUIT 1

VDD

33 kΩ

VDD

Q1

10 kΩ

40 kΩ

RESET

MCP2122

Note 1: Resistors should be adjusted for the

characteristics of the transistor.

2: This circuit will activate reset when

VDD goes below (Vz + 0.7V),

where Vz = Zener voltage.

FIGURE 2-4:

VDD

R1

R2

EXTERNAL BROWN-OUT

PROTECTION CIRCUIT 2

VDD

Q1

40 kΩ

RESET

MCP2122

Note 1: This circuit is less expensive, but

less accurate. Transistor Q1 turns

off when VDD is below a certain level

such that:

VDD •

R1 = 0.7V

R1 + R2

2: Resistors should be adjusted for the

characteristics of the transistor.

DS21894C-page 6

Preliminary

© 2007 Microchip Technology Inc.

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