FA5604 Datasheet, PDF (24/31 Pages) Fuji Electric – FUJI Power Supply Control IC

FA5604/5605/5606
(1-2)If the startup/shutdown voltages are set
If the startup/shutdown voltages are set, connect the resistor R2 between the starting resistor R1 and the
VCC-GND as shown in Fig. 19. At this time, the starting resistor R1 shall satisfy the following three relational
expressions. Set a relatively small value for R1 considering the temperature characteristics and the like.
(a) To supply 35 A (max) of the startup current at 19.5 V (max) of the on threshold voltage of UVLO:
(Condition for startup)
V1 19.5
R1 
19.5
0.035 
R2
····· (4)
(b) To supply 230 A (max) of the IC consumption current (VCC = 10.5 V) during the latch operation:
(Condition for the latch)
V1 10.5
R1 
10.5
0.23 
R2
········ (5)
(c) To supply 250 A (max) of the IC consumption current (VCC = 10.5 V) during off-state of the on-off function:
(Condition for on-off state)
Where,
R1: starting resistance [kΩ]
V1 10.5
R1 
10.5
0.25 
R2
····· (6)
If connecting the starting resistor before rectification (AC line), VIN is:
V1  ² Vac

If connecting the starting resistor after rectification (DC line), VIN is:
V1  2 Vac
(Vac = an effective value of the AC input voltage)
Example: On the condition that R2 = 22 kΩ and the startup at Vac = 80 V (VIN = 113 V) or less when connecting the
starting resistor after rectification
113 19.5
Condition for startup: R1 
19.5
0.035 
22
R1  101k
113  10.5
Condition for maintaining the latch: R1 
10.5
0.23 
22
R1  145k
113 10.5
Condition for maintaining the off-state: R1 
10.5
0.25 
22
R1  141k
Therefore, 101kΩ or less of the starting resistance is required.
In the case of R1 = 100 kΩ:
The approximate starting voltage is:
VIN

R1


0.035


19.5
R2



 19.5

100

_

0.035

19.5
22



 19.5

112V
The approximate latch release voltage is:
VIN

R1


0.23


10.5
R2



 10.5

100




0.23

10.5
22




10.5

81.2V
As shown above, the condition that the latch release voltage is less than the starting voltage is satisfied.
If neither the latch operation nor the on-off function is not used, it is enough to satisfy only the formula (4).
Fuji Electric Co., Ltd.
AN-033E Rev.1.2
April-2011
24
http://www.fujielectric.co.jp/products/semiconductor/