HA16116 Hitachi Semiconductor, HA16116 Datasheet - Page 16

• Manufacturer Part Number: HA16116
• Description: Switching Regulator for Chopper Type DC/DC Converter
• Manufacturer: Hitachi Semiconductor

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
16
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)
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.
T
Where, V
T
OFF
ON
= C
= C
= C
the pulse-by-pulse current limiter is operating.
ON/OFF
ON/OFF
ON/OFF
BE
0.7 V
R
R
(R
B
B
A
ln1.5
+ R
ln
OFF
B
)
3V
2V
OFF
is a function of V
ln
BE
BE
has elapsed.
1
V
V
On duty*
Figure 6.3
IN
IN
1
1
t
2V
3V
ON
BE
BE
On duty*
T
1
IN
. Further, according to this setting, when V
0.4
C
ON/OFF
Dead band voltage
On duty =
Where T = 1/f
ON
when the pulse-by-pulse current
Point at which current
limiter operate
ON
R
B
becomes.
t
ON
T
OSC
1
On duty*
1
IN
is