MIC3832 Просмотр технического описания (PDF) - Micrel
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MIC3832 Datasheet PDF : 10 Pages
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MIC3832/3833
Micrel
Pin Description
Pin Number
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
Pin Name
GND
PWM
Q
VDD
5V REF
EA –
EA +
EA OUT
NC
SHDN
MDC/SS
CMR
SYNC
RT
CT
Q
Pin Function
Ground: Use as single-point ground tie point.
PWM Output: Variable duty-cycle totem pole output.
Switch (Output): Totem pole output. Noninverting 50% duty cycle output
(180° out-of-phase with Q with no dead time).
Supply Voltage (Input): Clamped to 22V by internal zener diode.
5V Bandgap Reference (Output)
Inverting Error Amplifier Input
Noninverting Error Amplifier Input
Error Amplifier Output: Connect to the appropriate feedback network to
adjust the open loop gain or frequency response.
No Connection: Do not use—leave open.
Overcurrent Shutdown (Input): >1 V disables outputs, >1.25V initiates soft-
start restart. For cycle-by-cycle current limiting, even in voltage-mode control
applications, connect to current sensor. If current sense is not used, connect
to GND.
Maximum Duty Cycle/Soft Start (Input): Apply a dc voltage to adjust maxi-
mum duty cycle (see chart). Adjust soft start by adding capacitance to
increase turn-on time during initial start up or restart after overcurrent
shutdown.
Current Mode Ramp: Feed point for a sample of inductor current when using
current mode control. For voltage-mode control, connect directly to the CT
pin.
Synchronization (Input): AC coupled input from an external master clock
(reference) signal. If not used, leave unconnected. A high (>1.5V) resets the
CT ramp.
Oscillator Timing Resistor: Connect 4kΩ minimum resistor to GND.
Oscillator Timing Capacitor: Connect capacitor to GND. See “Typical
Characteristics: Discharge Time” graph for capacitor value.
Maximum oscillator frequency =
1
2 × (discharge time)
Switch (Output): Totem pole output. Inverting 50% duty cycle output (180°
out-of-phase with Q with no deadtime).
4-136
April 1998
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