ha16116fpj Renesas Electronics Corporation., ha16116fpj Datasheet - Page 11

• Manufacturer Part Number: ha16116fpj
• Description: Switching Regulator For Chopper Type Dc/dc Converter
• Manufacturer: Renesas Electronics Corporation.

HA16116FP/FPJ, HA16121FP/FPJ
3.2 Soft Start (SST) Setting (each channel)
When the power is turned on, the soft start function gradually raises V
PWM output pulse width gradually widens. This function is realized by adding a capacitor C
pin. The function is realized as follows.
In the figure 3.2, the DB pin is clamped internally at approximately 0.8 V, which is 0.2 V lower than the
triangle wave V
During soft start, the DB pin voltage in the figure below is as expressed in the following equation.
How to select values: If the soft start time t
overshoot. To prevent this, set t
Rev.2.0, Sep.18.2003, page 11 of 33
C
V
ST
DB
To Vref
t
t
Here,
A
B
R
R
: Standby time until PWM pulse starts widening.
: Time during which SST is in effect.
V
t
1
2
0.8
DB
SST
= T ln
TL
E/O
C
= V
= 1.0 V typ.
T
5k
DB
From UVL
1
1
+
+
PWM
comparator
e
V
0.8
DB
t
SST
T
t
Figure 3.1 Dead Band Duty Setting
0.8
to a few tens of ms or above.
,
0.8V
T = C
,
V
t
IN
SST
SST
ST
= t
is too short, the DC/DC converter output voltage will tend to
(R
PWM
pulse
output
A
+ t
1
// R
B
2
)
Booster
channel
Step-down/
inverting
channel
V
V
V
V
TH
E/O
DB
TL
t
OFF
DB
T
t
On
On
(refer to section 3.1), and the
ON
Off
Off
ST
1.6 V typ
1.0 V typ
V
GND
V
GND
to the DB
IN
IN