MIC38C44A PWM Controllers Datasheet

MIC38C44A Datasheet, PDF, Equivalent


Part Number

MIC38C44A

Description

BiCMOS Current-Mode PWM Controllers

Manufacture

Micrel Semiconductor

Total Page 9 Pages
Datasheet
Download MIC38C44A Datasheet


MIC38C44A
MIC38C42A/43A/44A/45A
Micrel, Inc.
MIC38C42A/43A/44A/45A
BiCMOS Current-Mode PWM Controllers
General Description
Features
The MIC38C4xA are fixed frequency, high performance,
• Fast 40ns output rise and 30ns output fall times
current-mode PWM controllers. Micrel’s BiCMOS devices
• –40°C to +85°C temperature range
are pin compatible with 384x bipolar devices but feature
meets UC284x specifications
several improvements.
• High-performance, low-power BiCMOS Process
Undervoltage lockout circuitry allows the ’42 and ’44 versions
to start up at 14.5V and operate down to 9V, and the ’43 and
’45 versions start at 8.4V with operation down to 7.6V. All
versions operate up to 20V.
When compared to bipolar 384x devices operating from a
15V supply, start-up current has been reduced to 50 µA
typical and operating current has been reduced to 4.0mA
typical. Decreased output rise and fall times drive larger
MOSFETs, and rail-to-rail output capability increases effi-
ciency, especially at lower supply voltages. The MIC38C4xA
• Ultralow start-up current (100µA typical)
• Low operating current (4mA typical)
• CMOS outputs with rail-to-rail swing
500kHz current-mode operation
• Trimmed 5V bandgap reference
• Pin-for-pin compatible with UC3842/3843/3844/3845
• Trimmed oscillator discharge current
• UVLO with hysteresis
• Low cross-conduction currents
Applications
also features a trimmed oscillator discharge current and
bandgap reference.
• Current-mode, off-line, switched-mode power supplies
• Current-mode, dc-to-dc converters.
The MIC38C4xA family is available in 8-pin SOIC and MSOP- • Step-down “buck” regulators
8 (MM8) package options
• Step-up “boost” regulators
• Flyback, isolated regulators
For fast rise and fall times and higher output drive, refer to the
MIC38HC4x.
• Forward converters
• Synchronous FET converters
Functional Diagram
VDD
7
VREF
8
RT/CT
4
FB
2
2.5V
5V
Reference
Oscillator
2R
R
UVLO
TQ
S
R
Q
OUT
6
COMP
1
GND ISNS
53
MIC38C42A, MIC38C43A (96% max. duty cycle) versions only
MIC38C44A, MIC38C45A (50% max. duty cycle) versions only
MM8 is a trademark of Micrel, Inc.
Micrel, Inc. • 2180 Fortune Drive • San Jose, CA 95131 • USA • tel + 1 (408) 944-0800 • fax + 1 (408) 474-1000 • http://www.micrel.com
http://www.Datasheet4U.com
April 2005
1 M9999-042205

MIC38C44A
MIC38C42A/43A/44A/45A
Micrel, Inc.
Ordering Information
Part Number
Standard
Pb-Free
MIC38C42ABM
MIC38C42AYM
MIC38C43ABM
MIC38C43AYM
MIC38C44ABM
MIC38C44AYM
MIC38C45ABM
MIC38C45AYM
MIC38C42ABMM
MIC38C42AYMM
MIC38C43ABMM
MIC38C43AYMM
MIC38C44ABMM
MIC38C44AYMM
MIC38C45ABMM
MIC38C45AYMM
Temperature
Range
–40°C to +85°C
–40°C to +85°C
–40°C to +85°C
–40°C to +85°C
–40°C to +85°C
–40°C to +85°C
–40°C to +85°C
–40°C to +85°C
Package
8-pin SOIC
8-pin SOIC
8-pin SOIC
8-pin SOIC
8-pin MM8™
8-pin MM8™
8-pin MM8™
8-pin MM8™
Refer to the Part Number Cross Reference for a listings of Micrel devices equivalent to UC284x and UC384x devices.
Selection Guide
Duty Cycle
0% to 96%
0% to 50%
UVLO Thresholds
Startup 8.4V
Startup 14.5V
Minimum Operating 7.6V Minimum Operating 9V
MIC38C43A
MIC38C42A
MIC38C45A
MIC38C44A
M9999-042205
2
April 2005


Features MIC38C42A/43A/44A/45A Micrel, Inc. MIC 38C42A/43A/44A/45A BiCMOS Current-Mode PWM Controllers General Description Th e MIC38C4xA are fixed frequency, high p erformance, current-mode PWM controller s. Micrel’s BiCMOS devices are pin co mpatible with 384x bipolar devices but feature several improvements. Undervolt age lockout circuitry allows the ’42 and ’44 versions to start up at 14.5V and operate down to 9V, and the ’43 and ’45 versions start at 8.4V with o peration down to 7.6V. All versions ope rate up to 20V. When compared to bipola r 384x devices operating from a 15V sup ply, start-up current has been reduced to 50 µA typical and operating current has been reduced to 4.0mA typical. Dec reased output rise and fall times drive larger MOSFETs, and rail-to-rail outpu t capability increases efficiency, espe cially at lower supply voltages. The MI C38C4xA also features a trimmed oscilla tor discharge current and bandgap refer ence. The MIC38C4xA family is available in 8-pin SOIC and MSOP8 (MM8) pack.
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