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Power-On Reset

V+

TLV301x

C

10 nF

1

DI

R

1

1 M

Ω

R

PULLUP

(1)

10 k

Ω

RESET

MSP430

1.242 V

REF

(1) Use R

with the TLV3011 only.

PULLUP

+

–

Relaxation Oscillator

V+

F = 724 Hz

V+

2/3 (V+)

1/3 (V+)

R

2

1 M

Ω

R

1

1 M

Ω

R

2

1 M

Ω

R

2

1 M

Ω

V

OUT

V

C

V+

t

C

1000 pF

T

1

T

2

t

TLV3012

TLV3011-EP, TLV3012-EP

SGLS349 – OCTOBER 2006

APPLICATION INFORMATION (continued)

The reset circuit shown in Figure 25 provides a time-delayed release of reset to the MSP430 microcontroller.

Operation of the circuit is based on a stabilization time constant of the supply voltage, rather than on a

predetermined voltage value. The negative input is a reference voltage created by the internal voltage reference.

The positive input is an RC circuit that provides a power-up delay. When power is applied, the output of the

comparator is low, holding the processor in the reset condition. Only after allowing time for the supply voltage to

stabilize does the positive input of the comparator become higher than the negative input, resulting in a high

output state, releasing the processor for operation. The stabilization time required for the supply voltage is

adjustable by the selection of the RC component values. Use of a lower-valued resistor in this portion of the

circuit does not increase current consumption, because no current flows through the RC circuit after the supply

has stabilized.

Figure 25. TLV3011 or TLV3012 Configured as Power-Up Reset Circuit for the MSP430

The TLV3012 can be configured as a relaxation oscillator to provide a simple and inexpensive clock output (see

Figure 26). The capacitor is charged at a rate of T = 0.69RC and discharges at a rate of 0.69RC. Therefore, the

Figure 26. TLV3012 Configured as Relaxation Oscillator

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