MITSUBISHI SEMICONDUCTOR < STANDARD LINEAR IC >
GENERAL PURPOSE HIGH SPEED PWM CONTROL IC
FUNCTION DESCRIPTION AND APPLICATION
(1) EA IN, EA OUT TERMINAL
Circuit for EAOUT terminal is connected to constant current
load(100µA typ.) shown in Fig.1. Output voltage of error
amp. is controlled by the output transistor to provide current-
sense comp. with the controlled voltage.
To PWM comp.
Fig.1 Circuit diagram of EAOUT terminal
Peripheral circuit of Error Amp
Detected voltage devided by R1 and R2 is input to EAIN terminal in such case as fly-back system where
VCC line voltage is proportional to output voltage, or in the case that the voltage detection is made on the
primary side. In this case operating region is set by R1 and R2, and AC gain by R1// R2, RF.
From detecting voltage
Fig.2 Method to detect the voltage on the primary side
In the case that feedforward system by photo-coupler is applied, following two methods are available.
One is the method by error amp. as in Fig.3-1, the other is by the direct connection to photo-coupler as in
When photo-coupler is directly connected to EAOUT terminal, input terminal of error amp. is connected to
GND, photo-coupler is connected directly to EAOUT terminal.
Fig.3-1 Method to use photo-coupler (1)
Fig.3-2 Method to use photo-coupler (2)