FA5604 Datasheet, PDF (23/31 Pages) Fuji Electric – FUJI Power Supply Control IC

FA5604/5605/5606
(1-1)If the startup/shutdown voltages are not set
If the startup/shutdown voltages are not set, connect only the starting resistor R1. 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 
0.035
·········· (1)
(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 
0.23
········· (2)
(c) To supply 250 A (max) of the IC consumption current (VCC = 10.5 V) during off-state of the on-off function:
V1  10.5
(Condition for on-off state) R1 
0.25
······ (3)
Where,
R1: starting resistance [kΩ]
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 of startup at Vac = 80 V (VIN = 113 V) or less when connecting the starting resistor after
rectification
113  19.5
Condition for startup: R1 
R1  2.7M
0.035
113  10.5
Condition for maintaining the latch: R1 
R1  446k
0.23
113  10.5
Condition for maintaining the off-state: R1 
R1  410k
0.25
Therefore, 400kΩ or less of the starting resistance is required.
In the case of R1 = 200 kΩ:
The approximate starting voltage is:
VIN  0.035  200  19.5  26.5V
The approximate latch release voltage is: VIN  0.23  200  10.5  56.5V
As shown above, the latch release voltage is more than the starting voltage. If the input voltage is reduced for some
reason when the latch is stopped, startup and release of the latch are performed repeatedly.
If the latch release voltage is less than the starting voltage under the above condition, the starting resistance is about
40 kΩ or less and a large loss results.
If neither the latch operation nor the on-off function is not used, it is enough to satisfy only the formula (1)
Fuji Electric Co., Ltd.
AN-033E Rev.1.2
April-2011
23
http://www.fujielectric.co.jp/products/semiconductor/