MIC3832 查看數據表（PDF） - Micrel
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MIC3832 Datasheet PDF : 10 Pages
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MIC3832/3833
Micrel
MIC3832/3833
Current-Fed PWM Controllers
Not Recommended for New Designs
General Description
Features
The MIC3832 and MIC3833 are unique PWM controllers • 15.9V startup, up to 21V operation (MIC3832)
designed for current-fed, multiple-output or push-pull,
8.3V startup, up to 21V operation (MIC3833)
switched-mode power supply applications.
• 9.8V undervoltage lockout (MIC3832)
The MIC3832/3 features UVLO (undervoltage lockout) with
hysteresis, soft start with a programmable time constant,
cycle-by-cycle current limiting, a PWM latch to prevent mul-
tiple outputs due to noise or ringing, and front-edge blanking.
Current-fed topologies eliminate core saturation problems
caused by shoot through (cross conduction) of push-pull
circuits and reduce stress on the switching transistors.
The MIC3832/3 has one PWM stage capable of operating up
to 500kHz and two output stages, Q and Q, that operate at
one-half of the system frequency at a fixed 50% duty cycle.
7.8V undervoltage lockout (MIC3833)
• 0.5mA maximum startup current (40µA typical)
• 17mA typical operating current
• 50ns maximum rise and fall times
• 30kHz to 500kHz RC oscillator
• Voltage or current-mode control
• Cycle-by-cycle current limit
• Soft start function
• 5V 2% reference sources 20mA
• Totem-pole output drive stages
1A peak output drive current
The MIC3832 UVLO circuit permits startup when the supply • 22V zener clamp on supply pin
is above 15.9V and forces shutdown when the supply drops • PWM latch eliminates false outputs from noise or ringing
below 9.8V. The MIC3833 starts up above 8.3V and shuts • Adjustable maximum duty-cycle limit
4
down below 7.8V. An internal 22V zener diode provides low • 5MHz bandwidth error amplifier
power overvoltage protection.
The three output stages are totem-pole drivers capable of 1A Applications
peak current to external power MOSFETs, BJTs, or IGBTs. • High-power, multiple-output, switched-mode
The Q and Q outputs have an intentional 50ns overlap (no
power supplies and dc-to-dc Converters
dead time).
• Current-fed, push-pull, switched-mode
power supplies or dc-to-dc converters
• Isolated high-voltage supplies
Pin Configuration
1 GND
Q 16
2 PWM
3Q
4 VDD
5 5V REF
CT 15
RT 14
SYNC 13
CMR 12
6 EA – MDC/SS 11
7 EA +
SHDN 10
8 EA OUT
NC 9
DIP (N) or Wide SOIC (WM)
Ordering Information
Part Number
MIC3832BN
MIC3832BWM
MIC3833BN
MIC3833BWM
Temperature Range
Package
–40°C to +85°C 16-pin Plastic DIP
–40°C to +85°C 16-pin Wide SOIC
–40°C to +85°C 16-pin Plastic DIP
–40°C to +85°C 16-pin Wide SOIC
April 1998
4-135
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