ta1307p TOSHIBA Semiconductor CORPORATION, ta1307p Datasheet - Page 3

• Manufacturer Part Number: ta1307p
• Description: Integrated Circuit For Standby Power-supply Control
• Manufacturer: TOSHIBA Semiconductor CORPORATION

With outputting burst switching control pulse from IC, burst enegize of the TRANS is carried out.
connected to the comparator.
for the terminal 4 (FB IN terminal).
(pulse out) is stopped.
If pulse is stooped, in order not to control power-supply TRANS, it will stop supplying energy supplied to the output
of a power supply, and the output DC voltage of a power-supply will descend.
outputted.
Then, output DC voltage rises.
attached to a terminal 2 outside.
Terminal voltage and R are outside attachment resistance in 1 (V).
10 is a current ratio, sets current of a terminal 2 to 1/10, and makes it the charge/discharge current of a internal
50 pF capacitor. C = 50 (pF) (built-in capacitor value) V = 2 (V) (oscillation amplitude)
Voltage stabilized also at the time of a light load can be supplied.
It is the optimum IC for constituting the power-supply system for minute electric-power supply.
By this IC, the burst time of switching control pulse is decided by level of output ripple of a power-supply system.
As for the terminal 4 which is carrying out the monitor of the power-supply output-voltage value, another side is
The standard voltage value of this comparator has hysterisis, 2.5 V and 3 V fixation. (inside IC)
Since output DC voltage of a power supply is stabilized, power-supply output voltage is detected and it feedbacks
When the voltage value of a terminal 4 tends to become more than 3 V, switching control pulse of a terminal 7
If output DC voltage tends to become less than (V/2.5), switching control pulse of a terminal 7 (pulse out) will be
Power-supply TRANS is made to drive and PULSE supplies energy to a power-supply output.
Burst electric supply is realized by repeating the above-mentioned operation.
Hereafter, calculation using ripple level as an example
Voltage of V
V
*CTR = I
*I
For example, R1 = 10 kW, R2 = R3 = 1 kW, CTR = about 1, V
Internal oscillation circuit for obtaining output PULSE is built in.
Oscillation frequency of output PULSE can be set up by outside attachment resistance to a terminal 2.
Duty about 50% of output PULSE has been obtained.
Oscillation frequency is calculation from f = i/2 CV (Hz), I = 1 (V) /R/10, and it will be set to 25 kHz, if 20 kW is
out
Z
= I
= V
F
Calculation
z
+ I
C
+ V
V
V
V
Ripple in an output is 0.05 V.
/I
S
F
ref
out
out
out
, R3 is set up.
F
(minimum) = 2.5 V fixation and V
+ 1/CTR ´ R2/R1 ´ V
(minimum) = 4.85 V
(maximum) = 4.9 V.
and the terminal 2 is set output DC voltage to V
FB comparater
V
ref
2.5 V/3 V
Figure 2 Ripple Voltage Establish
FB
4
ref
V
cc
I
C
ref
I
I
(maximum) = 3 V fixation.
z
F
3
R2
V
z
F
= 3.9 V, V
ref
.
Is
V
F
out
= 0.7 V
(example)
2002-02-12
TA1307P