ha16116fpj Renesas Electronics Corporation., ha16116fpj Datasheet - Page 16

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

HA16116FP/FPJ, HA16121FP/FPJ
6.3 Calculating Intermittent Operation Timing
Intermittent operation timing is calculated as follows.
(1) T
(2) T
Note: 1. On duty is the percent of time the IC is on during one PWM cycle when the pulse-by-pulse
From the first equation (1) above, it is seen that the shorter the time T
limiter goes into effect (resulting in a larger overload), the smaller the value T
As seen in the second equation (2), T
switched on, the IC goes on only after T
Rev.2.0, Sep.18.2003, page 16 of 33
ON
OFF
time (the time until the IC is shut off when continuous overcurrent occurs)
time (when the IC is off, the time until it next goes on)
T
T
Where, V
OFF
ON
PWM output
(step-down channel)
Triangle wave
Note: On duty is the percent of time the IC is on during one PWM cycle when
current limiter is operating.
= C
= C
= C
ON/
ON/
the pulse-by-pulse current limiter is operating.
ON/
BE
OFF
OFF
OFF
0.7 V
R
R
(R
B
B
A
ln1.5
+ R
ln
B
)
3V
2V
OFF
ln
BE
BE
OFF
is a function of V
1
has elapsed.
V
V
On duty*
IN
IN
1
Figure 6.3
1
2V
3V
t
BE
BE
ON
On duty*
1
T
0.4
IN
. Further, according to this setting, when V
C
ON/
OFF
Dead band voltage
On duty =
Where T = 1/f
ON
when the pulse-by-pulse current
R
Point at which current
limiter operate
B
ON
becomes.
t
ON
1
T
OSC
On duty*
1
IN
is