HA16654 Hitachi Semiconductor, HA16654 Datasheet - Page 12

• Manufacturer Part Number: HA16654
• Description: PWM Controlled Switching Regulator
• Manufacturer: Hitachi Semiconductor

HA16654A, HA16664A Series
12
500 k
200 k
100 k
10 k
Formula for the oscillation frequency f
f = 1 / [ {C
The following table show empirical values of
a and b for different values of C
Also,
f
C
4.35 / (C
OSC Frequency vs. Timing Resistor (HA16654A)
T
220
560
(pF)
C
R
Vref : Reference voltage 5.0 (V) (Typ)
V
20 k
T
BE
T
T
(R
T
: Timing capacitor (F)
: Timing resistor ( )
: Base-emitter voltage 0.65 (V) (Typ)
T
R
Timing Resistor R (k )
+ 1
T
2.30
8.37
C = 560 pF
)
T
10
a
50 k
3
10
10
)(a R
6
6
C =220 pF
T
T
100 k
T
T
.
+ b) / (Vref
1.247
1.575
b
200 k
V
BE
)} + 100
200 k
150 k
100 k
10 k
10
9
]
OSC Frequency vs. Timing Resistor (HA16664A)
10
20 k
200
2
4
6
8
Timing Resistor R ( )
b
300
50 k
C (pF)
T
a
400 500 600
C = 560 pF
T
100 k
T
C = 220 pF
T
200 k
1.2
1.3
1.4
1.5
1.6