Pin functions
N
1
2
3
4
5
6
7
8
Function
COMP
V
FB
I
SENSE
R
T
/C
T
GROUND
OUTPUT
V
CC
V
ref
Description
This pin is the Error Amplifier output and is made for loop compensation.
This is the inverting input of the Error Amplifier. It is normall y connected to the switching power supply
output through a resistor divider.
A voltage proportional to inductor current is connected to this input. The PWM uses this information to
terminate the output switch conduction.
The oscillator frequency and maximum Output duty cycle are programmed by connecting resistor R
T
to V
ref
and capacitor C
T
to ground.
This pin is the combined control circuitry and power ground.
This output directly drives the gate of a power MOSFET. Peak currents up to 1A are sourced and sink by
this pin.
This pin is the positive supply of the integrated circuit.
This is the reference output. It provides charging current for capacitor C
T
through resistor R
T
.
Application information
2.5V
1mA
V
FB
COMP
2
1
Figure 1. Error Amp Configuration
V
CC
7
ON/OFF COMMAND TO S/R OF IC
I
CC
MIK3842 MIK3843
MIK3844 MIK3845
13mA
V
ON
V
OFF
16V
10V
8.4V
7.6V
0.2mA
V
CC
V
OFF
V
ON
During UVLO, the Output is low
Figure 2. Undervoltage Lockout
ERROR
AMP
+
V
FB
2
_
2R
1V
R
CURRENT
SENSE
COMPARATOR
COMP 1
I
S
R
CURRENT
SENSE
3
5
R
S
C
GND
Peak current is determined by
I
S max
1.0V
R
S
Figure 3. Current Sense Circuit
BEIJING ESTEK ELECTRONICS CO.,LTD
3
ESTEK [ Estek Electronics Co. Ltd ]
