upc1909 Renesas Electronics Corporation., upc1909 Datasheet - Page 25

• Manufacturer Part Number: upc1909
• Description: Switching Regulator Control Ic
• Manufacturer: Renesas Electronics Corporation.

4.5 Duty Settings
4.5.1 Maximum duty setting
and OUT
current is limited, the OUT
and OUT
set to between 60 and 65%. This is because the duty conversion of OUT
about 75%. For details, refer to 4.7 Overcurrent Limiter Settings.
4.5.2 Minimum duty limit
on the value of “OUT
be reset, and a minimum duty limit will have to be set for OUT
determined. Because the DTC
than the DTC
4.5.3 Soft start
V
becomes low level and the soft start capacitor is initialized.
In the steady operation state (DTC
Note that when pulse-by-pulse current limitation is being applied using the OC pin, the maximum duty of OUT
There is no limit to the maximum duty of OUT
When OUT
This IC incorporates a transistor for discharging the soft start capacitor connected between the DCT
There is no such transistor incorporated on the DTC
CC
falls below the operation stopped voltage (5 V TYP.) or if the ON/OFF pin becomes low level (off), the DTC
2
2
. To set the duty as an independent FB input at times such as at startup, during low voltage input, and when the
via the DTC
1
1
is operating at maximum duty, if OUT
voltage, the DTC
1
1
ON time + t
and DTC
1
and OUT
1
1
pin is also the input of PWM comparator 2 on the OUT
2
voltage is compared with dC
pins, respectively, as shown in Figure 4-9.
qc
2
+ t
2
< FB < DTC
outputs must be set to their maximum duty values. Set the maximum duty for OUT
Figure 4-9. Maximum Duty Settings in PC1909
qd
”. If OUT
2
.
Data Sheet G14309EJ2V0DS00
2
1
), the duty during operation at the FB voltage is determined by OUT
has 0% duty when active clamping, the transformer will not be able to
2
2
is not output, it may inadvertently be set to a duty of 0%, depending
side.
T
and the minimum duty of OUT
2
14
13
5
3
at the same time the maximum duty of OUT
V
DTC
DTC
GND
REF
1
sets the reset level of the internal OC circuit to
1
2
2
side, if the FB voltage is higher
2
is limited.
1
pin and GND. If
PC1909
1
should be
1
1
25
pin
is
1
1