TLV340X BURR-BROWN [Burr-Brown Corporation], TLV340X Datasheet - Page 9

• Manufacturer Part Number: TLV340X
• Description: Nanopower, 1.8V, SOT23 Comparator with Voltage Reference
• Manufacturer: BURR-BROWN [Burr-Brown Corporation]

POWER-ON RESET
The reset circuit shown in Figure 4 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 ap-
plied, 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 will not
increase current consumption because no current flows
through the RC circuit after the supply has stabilized.
FIGURE 4. The TLV3011 or TLV3012 Configured as a
TLV3011, TLV3012
DI
NOTE: (1) Use R
SBOS300B
Power Up Reset Circuit for the MSP430.
R
1M
C
10nF
1
1
V+
1.242V
PULL-UP
TLV301x
REF
with the TLV3011 only.
R
10k
PULL-UP
(1)
RESET
MSP430
www.ti.com
The reset delay needed depends on the power-up character-
istics of the system power supply. R
allow enough time for the power supply to stabilize. D
provides rapid reset if power is lost. In this example, the
R
RELAXATION OSCILLATOR
The TLV3012 can be configured as a relaxation oscillator as
in Figure 5 to provide a simple and inexpensive clock output.
The capacitor is charged at a rate of T = 0.69RC. It also
discharges at a rate of 0.69RC. Therefore, the period is
T = 1.38RC. R
FIGURE 5. TLV3012 Configured as a Relaxation Oscillator.
1
V+
• C
1
time constant is 10mS.
1M
1000pF
R
2
C
1
may be a different value than R
R
1M
2
TLV3012
2/3 (V+)
1/3 (V+)
V+
1M
1M
R
R
V+
1
2
V
C
T
1
T
1
2
and C
V
OUT
F = 724Hz
1
are selected to
2
.
t
t
9
1