HA16120FP HITACHI [Hitachi Semiconductor], HA16120FP Datasheet - Page 6

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

HA16114P/PJ/FP/FPJ, HA16120FP/FPJ
Guide to the Functional Description
The description covers the topics indicated below.
Note: 1.
1. Sawtooth Oscillator (Triangle Wave)
1.1 Operation and Frequency Control
The sawtooth wave is a voltage waveform from which the PWM pulses are created (See figure 1). The
sawtooth oscillator operates as follows. A constant current I
is fed continuously to an external timing capacitor C
threshold voltage V
to flow from C
closes the switching transistor, stopping the 3I
sawtooth wave.
The value of I
5 k
Internal resistances R
at approximately 1.6 V and 1.0 V.
6
1.
2.
3.
4.
(I
Oscillator
frequency
(f
synchronization
DC/DC output
voltage setting
and error
amplifier usage
Dead-band and
soft-start settings
Output stage and
power MOS FET
driving method
OSC
O
P.GND is a high-current ( 1 A maximum peak) ground pin connected to the totem-pole output circuit.
GND is a low-current ground pin connected to the Vref voltage reference. Both pins must be grounded.
220 A).
) control and
O
T
is 1.1 V/R
. When the C
TH
, the comparator output opens a switching transistor, allowing a 3I
A
, R
B
T
, and R
P.GND*
. The I
GND*
SYNC
T
IN( )
IN(+)
E/O
pin voltage drops below a threshold voltage V
C
R
C
set the peak and valley voltages V
T
T
1
1
O
current mirror has a limited current capacity, so R
1
2
3
4
5
6
7
8
(Top view)
O
discharge. Repetition of these operations generates a
T
. When the C
16
15
14
13
12
11
10
9
O
determined by an external timing resistor R
Vref
ADJ
DB
ON/OFF
TM
CL( )
V
OUT
IN
TH
T
and V
pin voltage exceeds a comparator
TL
of the sawtooth waveform
TL
5.
6.
7.
8.
, the comparator output
Vref adjustment,
undervoltage
lockout, and
overcurrent
protection
ON/OFF pin
usage
Intermittent
mode timing
during
overcurrent
Setting of
current limit
O
T
should be at least
discharge current
T