XR-2207M データシートの表示（PDF） - Exar Corporation

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XR-2207M

Voltage-Controlled Oscillator

Exar Corporation 

XR-2207

VCC

VCC

S2

I+ C

0.1µF

12

3

Binary

8

A

Keying Inputs 9 B

V+ C1

C2

XR-2207

10

GND

SWO 13

14

TWO

11

BIAS

R1 R2 R3 R4 V-

4 5 6 7 12

I-

R1 R2 R3 R4

RL

Square Wave

Output

Triangle Wave

Output

VEE

0.1µF

S1

Figure 4. Test Circuit for Split Supply Operation

OPERATING CONSIDERATIONS

Supply Voltage (Pins 1 and 12)

The XR-2207 is designed to operate over a power supply

range of $4V to $13V for split supplies, or 8V to 26V for

single supplies. Figure 5 shows the permissible supply

voltage for operation with unequal split supply voltages.

Figure 6 and Figure 7 show supply current versus supply

voltage Performance is optimum for $6V split supply, or

12V single supply operation. At higher supply voltages,

the frequency sweep range is reduced.

Ground (Pin 10)

For split supply operation, this pin serves as circuit

ground. For single supply operation, pin 10 should be AC

grounded through a 1µF bypass capacitor. During split

supply operation, a ground current of 2IT flows out of this

terminal, where IT is the total timing current.

Bias for Single Supply (Pin 11)

For single supply operation, pin 11 should be externally

biased to a potential between V+/3 and V+/2V (see

Figure 3). The bias current at pin 11 is nominally 5% of the

total oscillation timing current, IT.

Bypass Capacitors

The recommended value for bypass capacitors is 1µF

although larger values are required for very low frequency

operation.

Timing Resistors (Pins 4, 5, 6, and 7)

The timing resistors determine the total timing current, IT,

available to charge the timing capacitor. Values for timing

resistors can range from 2kΩ to 2MΩ; however, for

optimum temperature and power supply stability,

recommended values are 4kΩ to 200kΩ (see Figure 8,

Figure 9, Figure 10 and Figure 11). To avoid parasitic pick

up, timing resistor leads should be kept as short as

possible. For noisy environments, unused or deactivated

timing terminals should be bypassed to ground through

0.1µF capacitors.

Timing Capacitor (Pins 2 and 3)

The oscillator frequency is inversely proportional to the

timing capacitor, C. The minimum capacitance value is

limited by stray capacitances and the maximum value by

physical size and leakage current considerations.

Recommended values range from 100pF to 100µF. The

capacitor should be non-polarized.

Rev. 2.02

7

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