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MIC4574-5.0YN

P1-P3P4-P6P7-P7
June 2005 1 M9999-062105
MIC4574 Micrel, Inc.
MIC4574
200kHz Simple 0.5A Buck Regulator
General Description
The MIC4574 is a series of easy to use fixed and adjustable
BiCMOS step-down (buck) switch-mode voltage regulators.
The 200kHz MIC4574 duplicates the pinout and function of
the 52kHz LM2574. The higher switching frequency may
allow up to a 2:1 reduction in output filter inductor size.
The MIC4574 is available in 3.3V, and 5V fixed output
versions or a 1.23V to 20V adjustable output version. Both
versions are capable of driving a 0.5A load with excellent line
and load regulation.
The feedback voltage is guaranteed to ±2% tolerance for
adjustable versions, and the output voltage is guaranteed to
±3% for fixed versions, within specified voltages and load
conditions. The oscillator frequency is guaranteed to ±10%.
In shutdown mode, the regulator draws less than 200µA
standby current. The regulator performs cycle-by-cycle cur-
rent limiting and thermal shutdown for protection under fault
conditions.
This series of simple switch-mode regulators requires a
minimum number of external components and can operate
using a standard series of inductors. Frequency compensa-
tion is provided internally.
The MIC4574 is available in the DIP (N) package and is rated
over the industrial temperature range.
Data sheets and support documentation can be found on
Micrel’s web site at www.micrel.com.
Typical Application
C1
47µF
35V
D1
1N5819
C2
220µF
16V
L1
100µH
SGND
FB
SW
MIC4574-5.0BN
SHDN
8V to 24V
5.0V/0.5A
V
IN
PGND
24
1
73
5
Shutdown
Enable
Fixed Regulator
Features
•Fixed 200kHz operation
• 3.3V, 5V, and adjustable output versions
•Voltage over specified line and load conditions:
Fixed version: ±3% max. output voltage
Adjustable version: ±2% max. feedback voltage
•Guaranteed 0.5A switch current
•Wide 4V to 24V input voltage range
•Wide 1.23V to 20V output voltage range
•Requires minimum external components
•< 200µA typical shutdown mode
• 75% efficiency (adjustable version > 75% typ.)
•Standard inductors and capacitors are
25% of typical LM2574 values
•Thermal shutdown
•Overcurrent protection
• 100% electrical thermal limit burn-in
Applications
•Simple high-efficiency step-down (buck) regulator
•Efficient preregulator for linear regulators
•On-card switching regulators
•Positive-to-negative converter (inverting buck-boost)
• Isolated flyback converter using minimum external
components
•Negative boost converter
Micrel, Inc. • 2180 Fortune Drive • San Jose, CA 95131 • USA • tel + 1 (408) 944-0800 • fax + 1 (408) 474-1000 • http://www.micrel.com
MIC4574 Micrel, Inc.
M9999-062105 2 June 2005
Ordering Information
Part Number Temperature
Standard Pb-Free Voltage Range Package
MIC4574-3.3BN MIC4574-3.3YN 3.3V –40°C to +85°C 8-pin DIP
MIC4574-5.0BN MIC4574-5.0YN 5.0V –40°C to +85°C 8-pin DIP
MIC4574BN MIC4574YN Adjustable –40°C to +85°C 8-pin DIP
Pin Description
Pin Number Pin Name Pin Function
1FBFeedback (Input): Output voltage feedback to regulator. Connect to output
of supply for fixed versions. Connect to 1.23V tap of resistive divider for
adjustable versions.
2 SGND Signal Ground.
3 SHDN Shutdown (Input): Logic low enables regulator. Logic high (> 2.4V) shuts
down regulator.
4 PGND Power Ground.
5 VIN Supply Voltage (Input): Unregulated +4V to +24V supply voltage.
7SWSwitch (Output): Emitter of NPN output switch. Connect to external storage
inductor and Shottky diode.
6, 8 NC Not internally connected. Solder to printed circuit for maximum heat transfer.
Pin Configuration
1
2
3
4
8
7
6
5
FB
SGND
SHDN
PGND
NC
SW
NC
V
IN
8-Pin DIP (N)
June 2005 3 M9999-062105
MIC4574 Micrel, Inc.
Electrical Characteristics (Note 4)
V
IN
=12V; I
LOAD
= 100mA; T
A
= 25°C, bold values indicate –40°C ≤ T
A
≤ +85°C; unless noted
Parameter Condition Min Typ Max Units
MIC4574 [Adjustable]
Feedback Voltage 1.217 1.230 1.243 V
Feedback Voltage 8V ≤ V
IN
≤ 24V, 0.1A ≤ I
LOAD
≤ 0.5A 1.193 1.230 1.267 V
1.180 1.280 V
Efficiency I
LOAD
= 0.5A, V
OUT
= 5V 77 %
Feedback Bias Current 50 100 nA
500 nA
MIC4574-3.3
Output Voltage 3.234 3.3 3.366 V
Output Voltage 6V ≤ V
IN
≤ 24V, 0.1A ≤ I
LOAD
≤ 0.5A 3.168 3.3 3.432 V
3.135 3.465 V
Efficiency 72 %
MIC4574-5.0
Output Voltage 4.900 5.0 5.100 V
Output Voltage 8V ≤ V
IN
≤ 24V, 0.1A ≤ I
LOAD
≤ 0.5A 4.800 5.0 5.200 V
4.750 5.250 V
Efficiency 77 %
MIC4574 / -3.3 / -5.0
Oscillator Frequency 180 200 220 kHz
Saturation Voltage I
OUT
= 0.5A 1 1.3 V
1.5 V
Maximum Duty Cycle (On) FB connected to 0V 90 95 %
Current Limit Peak Current, t
ON
≤ 3µs 0.7 1.0 1.6 A
0.65 1.8 A
Output Leakage Current V
IN
= 24V, FB connected to 6V
Output = 0V 0 2 mA
Output = –1V 7.5 35 mA
Quiescent Current 510mA
Standby Quiescent Current SHDN = 5V (regulator off) 50 200 µA
SHDN Input Logic Level V
OUT
= 0V (regulator off) 2.2 1.4 V
2.4 V
V
OUT
= 3.3V or 5V (regulator on) 1.2 1.0 V
0.8 V
SHDN Input Current SHDN = 5V (regulator off) 4 30 µA
SHDN = 0V (regulator on) –10 0.01 10 µA
Note 1. Exceeding the absolute maximum rating may damage the device.
Note 2. The device is not guaranteed to function outside its operating rating.
Note 3. Devices are ESD sensitive. Handling precautions recommended.
Note 4. Specification for packaged product only.
Note 5. The MIC4574 is not guaranteed to survive a short circuit to ground for input voltage above 24V.
Absolute Maximum Ratings (Note 1)
Supply Voltage (V
IN
), Note 5 ......................................+40V
Shutdown (V
SHDN
) ....................................... –0.3V to +36V
Output Switch (V
SW
) steady state ................................. –1V
Junction Temperature (T
J
) ...................................... +150°C
Storage Temperature ............................... –65°C to +150°C
ESD Rating, Note 3
Operating Ratings (Note 2)
Supply Voltage (V
IN
) ................................................... +24V
Package Thermal Resistance
θ
JA
Plastic DIP .................................................. 130°C/W
P1-P3P4-P6P7-P7

MIC4574-5.0YN

Mfr. #:
Buy MIC4574-5.0YN
Manufacturer:
Microchip Technology / Micrel
Description:
Switching Voltage Regulators 200kHz 0.5A Step-down Regulator
Lifecycle:
New from this manufacturer.
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