Star Micronics TSP200 +5V Line Voltage Detector Circuit, Equivalent Circuit, Voltage Detection IC

PRINCIPLES OF OPERATION

2-5. +5V Line Voltage Detector Circuit

The voltage-detection IC (IC3 in Fig. 2-13) detects momentary drops or unstable levels in the +5V line voltage. The following shows an IC3-equivalent circuit.

R1

R2

1.25V

VCC

1

S∝A typ

–

+

3

GND

–

4

Cd

5

OUT

Fig. 2-14 Equivalent Circuit, Voltage Detection IC

Figure 2-15 shows the IC’s operational timing. The IC asserts a reset signal at its output terminal when the -5V line voltage falls below 4.25V, thereby resetting the CPU and the gate array.

VCC Voltage

4.25V
0.8V	t

Output

Voltage

td td

t td = 0.34 × Cd (pF) [∝s]

Fig. 2-15 Operation Timing Chart

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