August 2005 1 MIC5156/5157/5158
MIC5156/5157/5158 Micrel, Inc.
MIC5156/5157/5158
Super LDO™ Regulator Controller
either 3.3V, 5.0V, or 12V. The MIC5158 can be configured
as a fixed 5V controller or programmed to any voltage from
1.3V to 36V using two external resistors.
The MIC5156 is available in an 8-pin DIP or SOIC. The
MIC5157 and MIC5158 are available in a 14-pin DIP or SOIC
which operate from –40°C to +85°C.
Features
• 4.5mA typical operating current
• <1µA typical standby current
• Low external parts count
• Optional current limit (35mV typical threshold)
• 1% initial output voltage tolerance in most configurations
• 2% output voltage tolerance over temperature
• Fixed output voltages of 3.3V, 5.0V (MIC5156)
• Fixed output voltages of 3.3V, 5.0V, 12V (MIC5157)
• Programmable (1.3 to 36V) with 2 resistors (MIC5156/8)
• Internal charge pump voltage tripler (MIC5157/8)
• Enable pin to activate or shutdown the regulator
• Internal gate-to-source protective clamp
• All versions available in DIP and SOIC
Applications
• Ultrahigh current ultralow dropout voltage regulator
• Constant high-current source
• Low parts count 5.0V to 3.3V computer supply
• Low noise/low-dropout SMPS post regulator
• High-current, current-limited switch
10A 5V to 3.3V Desktop Computer Regulator
General Description
The MIC5156, MIC5157, and MIC5158 Super Low-Dropout
(LDO) Regulator Controllers are single IC solutions for high-
current low-dropout linear voltage regulation. Super LDO™
Regulators have the advantages of an external N-channel
power MOSFET as the linear pass element.
The MIC5156/7/8 family features a dropout voltage as low
as the R
DS(ON)
of the external power MOSFET multiplied by
the output current. The output current can be as high as the
largest MOSFETs can provide.
The MIC5156/7/8 family operates from 3V to 36V. The
MIC5156 requires an external gate drive supply to provide
the higher voltage needed to drive the gate of the external
MOSFET. The MIC5157 and MIC5158 each have an inter-
nal charge pump tripler to produce the gate drive voltage.
The tripler is capable of providing enough voltage to drive a
logic-level MOSFET to 3.3V output from a 3.5V supply and
is clamped to 17.5V above the supply voltage. The tripler
requires three external capacitors.
The regulator output is constant-current limited when the
controller detects 35mV across an optional external sense
resistor. An active-low open-collector flag indicates a low
voltage of 8% or more below nominal output. A shutdown
(low) signal to the TTL-compatible enable control reduces
controller supply current to less than 1µA while forcing the
output voltage to ground.
The MIC5156-3.3 and MIC5156-5.0 controllers have inter-
nally fixed output voltages. The MIC5156 [adjustable] output
is configured using two external resistors. The MIC5157 is a
fixed output controller which is externally configured to select
1234
14131211
567
10
98
MIC5157
C
2+
C
2–
V
C
P
G
ND
F
LAG
3
.3V
5
V
C
1+
C
1
–
V
D
D
G
D
S
E
N
V
OU T
3.3V, 10A
V
IN
(3.61Vmin.)
0.1µF
1.0µF
0.1µF
R
S
R
S
= 0.035V /I
LIMIT
3mΩ
IRLZ44 (Logic Level MOSFET)
C
L
*
47µF
*Improves transient
response to load changes
Enable
Shutdown
47µF
10A Low-Dropout Voltage Regulator
123
876
4
5
MIC5156-3.3
V
P
G
ND
F
LAG
E
N
V
D
D
G
D
S
V
OU T
3.3V, 10A
V
IN
5V
0.1µF
R
S
R
S
= 0.035V /I
LIMIT
3mΩ
SMP60N03-10L
C
L
*
47µF
*I
mproves transient
response to load changes
+12V
Enable
Shutdown
47µF
Typical Applications
Super LDO 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
