LC8740C8A/B2A/96A

No.A0122-21/25

Recommended Oscillation Circuit and Sample Characteristics

The sample oscillation circuit characteristics in the table below is based on the following conditions:

• Recommended circuit parameters are verified by an oscillator manufacturer using a Sanyo provided oscillation

evaluation board.

• Sample characteristics are the result of the evaluation with the recommended circuit parameters connected

externally.

Table 1. Recommended oscillation circuit and sample characteristics (Ta = -10

°C to +70°C)

Recommended circuit

parameters

Oscillation

stabilizing

time

Frequency

Manufacturer

Oscillator

C1

[pF]

C2

[pF]

Rf

[

Ω]

Rd

[

Ω]

Operating

supply voltage

range

[V]

typ

[s]

max

[s]

Remarks

32.768kHz

Seiko Epson

C-002RX

18

18

OPEN

620k

4.5 to 5.5

1.00

1.50

Notes: The oscillation stabilizing time period is the time until the VCO oscillation for the internal system becomes

stable after the following conditions. (See Figure 3.)

1. The VDD becomes higher than the minimum operating voltage after the power is supplied.

2. The HOLD mode is released.

The sample oscillation circuit characteristics may differ applications. For further assistance, please contact with

oscillator manufacturer with the following notes in your mind.

• Since the oscillation frequency precision is affected by wiring capacity of the application board, etc., adjust the

oscillation frequency on the production board.

• The above oscillation frequency and the operating supply voltage range are based on the operating temperature of

-10

°C to +70°C. For the use with the temperature outside of the range herein, or in the application requiring high

reliability such as car products, please consult with oscillator manufacturer.

• When using the oscillator which is not shown in the sample oscillation circuit characteristics, please consult with

Sanyo sales personnel.

Since the oscillation circuit characteristics are affected by the noise or wiring capacity because the circuit is designed

with low gain in order to reduce the power dissipation, refer to the following notices.

• The distance between the clock I/O terminal (XT1 terminal XT2 terminal) and external parts should be as short as

possible.

• The capacitors’ VSS should be allocated close to the microcontroller’s GND terminal and be away from other GND.

• The signal lines with rapid state change or with large current should be allocated away from the oscillation circuit.

Figure 1 Recommended Oscillation Circuit

Figure 2 AC Timing Measurement Point

0.5VDD

C1

Rd

C2

X’tal

XT2

XT1

Rf