MB3817 Datasheet, PDF (14/29 Pages) Fujitsu Component Limited. – Switching Regulator Controller

MB3817
s METHOD OF SETTING THE OUTPUT CURRENT
The output circuit is comprised of a totem-pole configuration. Its output current waveform is such that the ON-
current value is set by constant current and the OFF-current value is set by a time constant. These output
currents are set using the equations below.
ON current: IO+ [mA] ^{.=. 500} (Voltage on output current-setting pin VE = 0.5 V)
RE [Ω]
OFF current: OFF-current time constant = proportional to the value of CB
• Output circuit
OFF current
setting
Q4
block
Q6
D1
Q5
(0.5 V)
CB1
7 CB
8
CB2
9
VCC
Outside putting PNP transistor
OFF
current
10
OUT
ON current
RE
11
VE
• Output current waveform
0
ON current
OFF current
t
14