High Efficiency, Synchronous
Step-Down Switching Regulators
a
ADP1149/1149-3.3/1149-5
FEATURES
P IN CO NFIGURATIO NS
Operation to 48 V Input Voltage
Ultrahigh Efficiency (Up to 95%)
Current Mode Operation for Excellent Line and Load
Transient Response
High Efficiency Maintained Over Wide Current Range
Logic Controlled Micropow er Shutdow n
Short Circuit Protection
Very Low Dropout Operation
Synchronous FET Sw itching for High Efficiency
Adaptive Nonoverlap Gate Drives
16-Lead P lastic D IP
16-Lead P lastic SO
CAP
16
15
14
13
12
PGATE
1
2
3
4
V
SD2
ADP1149
IN
V
REG GND
NGATE
PWR GND
CC
ADP1149-
3.3
PDRIVE
V
ADP1149-
5
CC
5
6
7
8
11 SIG GND
C
T
TOP VIEW
(Not to Scale)
APPLICATIONS
Notebook and Palm top Com puters
Portable Instrum ents
10
I
VFB (SD1)*
TH
9
SENSE+
SENSE–
Battery Operated Digital Devices
Industrial Pow er Distribution
Avionics System s
*FIXED OUTPUT VERSIONS = SD1
Telecom Pow er Supplies
GENERAL D ESCRIP TIO N
input range converters. Current-mode operation provides
excellent line and load transient response. T he operating cur-
rent level is user programmable via an external current sense
resistor.
T he ADP1149 is a family of synchronous step-down switching
regulator controllers featuring automatic-sleep mode to maintain
high efficiencies at low output currents. T hese devices drive
external complementary power MOSFET s at switching fre-
quencies up to 250 kHz using a constant off-time current-mode
architecture.
T he ADP1149 incorporates automatic power saving sleep
mode operation when load currents drop below the level
required for continuous operation. In sleep mode, standby
power is reduced to only about 8 mW at VIN = 12 V. In shut-
down, both MOSFET s are turned off.
Special onboard regulation and level-shift circuitry allow opera-
tion at input voltages from dropout to 48 V (60 V absolute
maximum). T he constant off-time architecture maintains con-
stant ripple current in the inductor, easing the design of wide
V
IN
C
IN
1N4148
100µF
100V
V
IN
P-CHANNEL
IRFR9024
CAP
P-GATE
0.068µF
V
CC
0.047µF
L*
62µH
3.3µF
R
SENSE**
V
P-DRIVE
CC
0.05Ω
V
ADP1149-5
OUT
D1
1N5819
5V/ 2A
SENSE+
SENSE–
SHUTDOWN 1
SHUTDOWN 2
0V = NORMAL
>2V = SHUTDOWN
1000pF
I
TH
3300pF
C
OUT
N-CHANNEL
IRFR024
N-DRIVE
C
220µF
T
C
T
S-GND
P,R-GNDS
1kΩ
470pF
*COILTRONICS CTX62-2-MP
**KRL SL-1-C1-0R050J
Figure 1. Typical Application
This inform ation applies to a product under developm ent. Its characteristics and specifications are subject to change without notice.
Analog Devices assum es no obligation regarding future m anufacture unless otherwise agreed to in writing.
To obtain the m ost recent version or com plete data sheet, call our fax retrieval system at 1-800-446-6212 or visit our World Wide Web site at http://www.analog.com .
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