TC96C55 Datasheet, PDF (9/9 Pages) TelCom Semiconductor, Inc – 3A OUTPUT PROGRAMMABLE POWER OSCILLATOR

3A OUTPUT PROGRAMMABLE
POWER OSCILLATOR
1
APPLICATIONS (Cont.)
Duty Cycle vs. Charge Current
Frequency in kHz
100
16
38
50
38 16
80
60
40
20
0
10 20 30 40 50 60 70 80 90 100
Charge Current in µA
ISINK = 100µA
Figure 6. Duty Cycle vs. Charge Current
+12V
.1µF
CONTROL
VOLTAGE
SOURCE
RCHG
8
3 _VREF ^VDD _OUT ⁷
4 _VR1
OUT
6
RDIS
C
2 _VIN
TC96C555
1
VR2
GND
OUTPUT
TC96C555
By connecting both resistors, R_CHG and R_DIS, to a
2 ^{voltage source instead of connecting to the 4V reference of}
Pin 3, one can increase or decrease the output frequency.
Increasing the voltage source to 5V will double the oscillator
frequency by doubling the voltage across both R_CHG and
R_DIS. Decreasing the voltage source to 3.5V will drop the
frequency in half.
Voltage Controlled Oscillator
RCHG = 51k, Rdis = 25.5k
3
1000K
100K
10pF
100pF
10K
1000pF
4
1K
0.01µF
100
0.1µF
10
3.25V
3.5V
4V
5V
7V
Control Voltage
Figure 8. Frequency vs Control
5
6
Figure 7. Voltage Controlled Power Oscillator
7
TELCOM SEMICONDUCTOR, INC.
8
4-167