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M51945A

Voltage Detecting, System Resetting IC Series

Renesas Electronics 

M51945A,B/M51946A,B

Circuit Current vs. Supply Voltage

(M51945B, M51946B)

800

600

Ta = –30°C

400

Ta = 25°C

200

Ta = 85°C

0

0

4

8

12 16

Supply Voltage VCC (V)

Example of Application Circuit

Reset Circuit of M5194xx Series

R1

Input

R2

Power-

supply

RL

Output

M5194xx

GND

Cd

VCC

Power-

supply

RESET (RESET)

Logic circuit

GND

Figure 1 Reset Circuit of M5194xx Series

Notes: 1. When the detecting supply voltage is 4.25 V, M51943 and M51944 are used and R1 and R2 are not necessary.

When the voltage is anything except 4.25 V, M51945 and M51946 are used. In this case, the detecting

supply voltage is 1.25 × (R1 +R2)/R2 (V) approximately. The detecting supply voltage can be set between 2

V and 15 V.

2. If the M5194xx and the logic circuit share a common power source, type A (built-in load type) can be used

whether a pull-up resistor is included in the logic circuit or not.

3. The logic circuit preferably should not have a pull-down resistor, but if one is present, add load resistor RL to

overcome the pull-down resistor.

4. It is better to use the M5195xx series to cause a delay, but if the delay is caused by the M5194xx series, the

delay capacitor Cd is applied between the output and GND.

5. When the reset terminal in the logic circuit is of the low reset type, M51943 and M51945 are used and when

the terminal is of the high reset type, M51944 and M51946 are used.

6. When a delay is necessary at both rise time and fall time, M51945 and M51946 are used and the series

resistors (R11, R12) are applied between the output and GND or instead of R1, and these connect the capacitor

between the connection point and GND. The connection point of the capacitor is fixed according to the ratio

of delay at fall/rise time.

7. When a negative supply voltage is used, the supply voltage side of M5194xx and the GND side are

connected to GND and the negative supply voltage respectively.

REJ03D0774-0200 Rev.2.00 Aug 20, 2007

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