ADP3088 pri

[ Pobierz całość w formacie PDF ]
PRELIMINARY TECHNICAL DATA
a
1 MHz, 750 mA Buck Regulator
Preliminary Technical Data
ADP3088
FEATURES
1 MHz PWM Frequency
Automatic PWM to Power Saving Mode at Light Load
Fully Integrated 1 A Power Switch
3% Output Regulation Accuracy over Temperature,
Line, and Load
100% Duty Cycle Operation
Simple Compensation
Output Voltage: 1.25 V to 10.5 V
Small Inductor and MLC Capacitors
Low Quiescent Current while Pulse Skipping
Thermal Shutdown
Fully Integrated Soft Start
Cycle-by-cycle Current Limit
FUNCTIONAL BLOCK DIAGRAM
IN
SW
CURRENT
SENSE
AMP
IN
PWM
COMPARATOR
1MHz
DRV
SQ
R
PROTECTION
LOGIC
(ILIM, OT)
RUN/STOP
COMPARATORS
ERROR
AMP
FB
COMP
g
m
APPLICATONS
PDAs and Palmtop Computers
Notebook Computers
PCMCIA Cards
Bus Products
Portable Instruments
GND
SOFT-START
TIMER
+
REF
1.245V
GND
GENERAL DESCRIPTION
The ADP3088 is a high frequency, non-synchronous PWM
step-down DC-DC regulator with an integrated 1A power
switch in a space-saving MSOP8 package. It provides high
efficiency, excellent dynamic response, and is very simple
to use.
The ADP3088’s 1 MHz switching frequency allows for
small, inexpensive external components, and the current
mode control loop is simple to compensate and eases noise
filtering. It operates in PWM current mode under heavy
loads and saves energy at lighter loads by switching auto-
matically into Power Saving mode. Soft start is integrated
completely on chip, as is the cycle-by-cycle current limit.
Capable of operating from 2.5 V to 11 V input, it is ideal for
many applications, including portable, battery power appli-
cations, where local point-of-use power regulation is re-
quired. Supporting output voltages down to 1.25 V, the
ADP3088 is ideal to generate low voltage rails, providing
the optimal solution in its class for delivering power effi-
ciently, responsively, and simply with minimal printed cir-
cuit board area.
The device is specified over the industrial temperature
range of -40 °C to +85°C.
ADP3088
10
µ
H
IN
SW
VOUT
1.8V
10µF
0.1µF
IN
GND
COMP
DRV
53.6k
GND
1N5817
+
FB
10µF
120k
Ω
470pF
20k
Figure 1.Typical Application
REV. PrI 2/8/02
Information furnished by Analog Devices is believed to be accurate and reli-
able. However, no responsibility is assumed by Analog Devices for its use, nor
for any infringements of patents or other rights of third parties which may
result from its use. No license is granted by implication or otherwise under any
patent or patent rights of Analog Devices.
One Technology Way, P.O. Box 9106, Norwood, MA 02062-9106, U.S.A.
Tel: 781/329-4700
www.analog.com
Fax: 781/326-8703
Analog Devices, Inc., 2002
ADP3088–SPECIFICATIONS
1
(V
IN
= +3.3 V, T
A
= -40°C to +85°C, unless otherwise noted)
PRELIMINARY TECHNICAL DATA
Parameter
Symbol
Conditions
Min
Typ
Max
Units
SUPPLY
Input Voltage Range
V
IN
DRV to GND
2.5
11
V
Quiescent Current
Operating
I
Q
VIN = 10 V, I
L
= 500 mA,
6
mA
DRV = GND
Shutdown
I
SD
V
COMP
= 0 V
15
40
µA
Ground Current
I
GND
2
Normal Operation
V
IN
= 11 V, I
L
= 500 mA,
2.5
3.6
mA
DRV = 2 V
Thermal Shutdown Threshold T
SD
160
°C
OSCILLATOR
Oscillator Frequency
f
SW
0.75
1
1.25
MHz
Minimum Sleep Duty Cycle
D
PSM
I
L
= 500 mA
14
TBD
%
Maximum Duty Cycle
D
MAX
100
%
Wake up Hysteresis
V
HYST
FB voltage drops below V
REF
20
30
40
mV
OUTPUT SWITCH
Switch On Voltage
V
IO
3
I
L
= 500 mA,
FB and DRV
0.25 0.4
V
tied to
GND
Current Limit Threshold
I
LIM
1.0
1.2
1.4
A
Leakage Current
V
IN
= 12 V
0.5
µA
ERROR AMPLIFIER
Reference Voltage Accuracy
V
REF
FB tied to COMP
1.222 1.245 1.265 V
Reference Voltage Line
FB tied to COMP,
.02
%/V
Regulation
V
IN
= 3 V to 12 V
Feedback Input Bias Current
I
FB
soft start expired
-50
1
50
nA
Maximum Output Current
I
COMP
,
SC
35
60
85
µA
Short Circuit Current
I
COMP
,
SD
V
COMP
= 0 V, activating
20
40
µA
shutdown
Transconductance
g
m
,
EA
V
FB
to I
COMP
480
µA/V
MODULATOR
Transconductance
g
m
,
MOD
V
COMP
to I
L
1
A/V
Control Offset Voltage
V
PWM
,
OS
0.90
V
Soft Start Time
t
SS
250
600
µs
Shutdown Threshold Voltage
V
COMP
,
SD
340
750
mV
Slope Compensation
m
SC
Effectively summed to I
SW
0.7
A/µs
NOTES
1 All limits at temperature extremes are guaranteed via correlation using standard Statistical Quality Control (SQC).
2 For higher efficiency operation, tie the DRV pin to the output for I
L
< 250 mA, and VIN > 3 V.
3 V(IN) - V(SW), includes voltage drop across internal current sensor.
Specifications subject to change without notice.
–2–
REV. PrI
PRELIMINARY TECHNICAL DATA
ADP3088
ABSOLUTE MAXIMUM RATINGS*
Input Supply Voltage ............................... –0.3 V to +12 V
Voltage on any pin with respect to GND .. –0.3 V to +12 V
(voltage on any pin may not exceed V
IN
)
Operating Ambient Temperature Range .. –40°C to +85°C
Operating Junction Temperature ......................... +125°C
θ
JA
1
(4-layer board) ......................................... +116°C/W
θ
JA
1
(2-layer board) ......................................... +159°C/W
Storage Temperature Range .................. –65°C to +150°C
Lead Temperature Range (Soldering, 10 sec.) ..... +300°C
Vapor Phase (60 sec) ........................................ +215°C
Infrared (15 sec) ............................................... +220°C
PIN FUNCTION DESCRIPTIONS
Pin
Mnemonic Function
1, 2
IN
Power Supply Input. Both pins
must be connected.
3,6
GND
Ground. Both pins must be con-
nected.
4
COMP
Feedback Loop Compensation
and Shutdown Input. An open
drain or collector used to pull
the pin to ground will shutdown
the device.
*This is a stress rating only; operation beyond these limits can cause the device
to be permanently damaged. Unless otherwise specified, all voltages are
referenced to GND.
5
FB
Feedback Voltage Sense Input.
This pin senses the voltage via
an external resistor divider.
1
θ
JA is specified for a device soldered in a circuit board
for SOT-23 packages. Following good PCB board layout guidelines can significantly reduce
7
DRV
This pin provides a separate
path for drive current to be con-
nected to ground.
JA.
8
SW
Switching Output.
ORDERING GUIDE
OUTLINE DIMENSIONS
Dimensions shown in inches and (mm).
Temperature Package Branding
Model Range Option Information
ADP3088ARM -40°C to +85°C MSOP-8 P0A
RM-8
8-Lead Mini/micro SOIC Package [Mini_SO]
0.122 (3.10)
0.114 (2.90)
PIN CONFIGURATION
8
5
VIN
VIN
GND
COMP
1
2
3
4
8
7
6
5
SW
DRV
GND
FB
0.122 (3.10)
0.114 (2.90)
0.199 (5.05)
0.187 (4.75)
1
4
ADP3088
PIN 1
0.0256 (0.65) BSC
0.120 (3.05)
0.112 (2.84)
0.120 (3.05)
0.112 (2.84)
0.043 (1.09)
0.037 (0.94)
0.006 (0.15)
0.002 (0.05)
33
27
0.018 (0.46)
0.008 (0.20)
SEATING
PLANE
0.011 (0.28
)
0.003 (0.08)
0.028 (0.71)
0.016 (0.41)
CAUTION
ESD (electrostatic discharge) sensitive device. Electrostatic charges as high as 4000 V readily
accumulate on the human body and test equipment and can discharge without detection.
Although the device features proprietary ESD protection circuitry, permanent damage may oc-
cur on devices subjected to high energy electrostatic discharges. Therefore, proper ESD
precautions are recommended to avoid performance degradation or loss of functionality.
REV. PrI
–3–
PRELIMINARY TECHNICAL DATA
JA is specified for the worst case conditions,
[ Pobierz całość w formacie PDF ]