HA16120FP HITACHI [Hitachi Semiconductor], HA16120FP Datasheet - Page 7

• Manufacturer Part Number: HA16120FP
• Description: Switching Regulator for Chopper Type DC/DC Converter
• Manufacturer: HITACHI [Hitachi Semiconductor]

The oscillator frequency f
At high frequencies the comparator delay causes the sawtooth wave to overshoot the 1.6 V threshold and
undershoot the 1.0 V threshold, and changes the dead-band thresholds accordingly. Select constants by
testing under implementation conditions.
R
I
O
T
Here,
Since
1.1 V
Current
mirror
t
t 2 =
t 3
V
f
f
OSC
1
OSC
H
=
0.8 s (comparator delay time)
=
V
External circuit
C
C
L
OSC
3
0.73
T
T
= 0.6 V
t
1
1.1 V/R
can be calculated as follows.
+ t
1.1 V/R
(V
(V
Figure 1.1 Equivalent Circuit of Oscillator
1
2
H
H
C
+ t
1 : 4
T
T
3
V
V
T
L
L
1
R
)
)
T
(Internal voltage)
+ 0.8 ( s)
Discharg
-ing 3I
C charging
t
t
1
2
V = 1.6 V typ
T
H
I
HA16114P/PJ/FP/FPJ, HA16120FP/FPJ
O
C
O
T
3.2 V
(Hz)
Oscillator
comparator
V = 1.0 V typ
L
t
R
1
C
: t
2
= 3 : 1
R
R
A
B
2.5 V
Vref
SYNC
circuit
Sync
7