AQ120
LDO Regulator Controller
SOT23-5 Package
Preliminary Specification
Revision 1.2
April 1, 2006
General Description
The AQ120 is a low cost LDO controller.
The AQ120 flexibility allows the setting of
the output voltage and controls up to 2
Amps of output current with a minimum
number of external components.
The open collector output is capable of
driving an external PNP transistor. A
temperature stable bandgap reference
(1.25 V) controls the output voltage and
is programmable through two external
resistors. The AQ120 if offered in the
very small SOT23-5 package.
Applications
•
Graphic cards
•
PC motherboards
•
Switching power supply post-regulation
•
Telecom equipment
•
DVD video player
Features
•
1.25V reference with 1.5% accuracy
•
Low current consumption
•
Offered in small SOT23-5 package
•
Wide Vin range: 2.5V to 18V
•
20mA drive current sink
•
RoHS compliant
available
Pin Configuration
Block Diagram
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AQ120
Acutechnology Semiconductor Inc.
AQ120
Typical Application
Note: The values of R1and R2 set the output voltage. The typical Vref is 1.25V
Pin Descriptions
Pin
1
2
3
4
5
Pin Name
DRIVE
GND
GND BIAS
VCC
VREF
Function
Output of error amplifier. 20 mA sink capability to drive PNP pass element
Ground
Must connect to GND for proper operation as an LDO Controller
Positive supply
Voltage programming pin; has a threshold of 1.25V.
Ordering Information
Device
AQ120
AQ120
Note:
The
Operating Tj
-40C˚
≤
85C˚
-40C˚
≤
85C˚
%Tol
1.5
1.5
Pkg Type
SOT-23-5
SOT-23-5
V
OUT
1.25V
1.25V
Wrap
T&R
T&R
Order Number
AQ120EX-M5-AJ-TR
AQ120EX-M5-AJ-TRL
TRL parts are Lead Free and RoHS compliant.
2
Rev. 1.2
April 1, 2006
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Acutechnology Semiconductor Inc.
AQ120
Absolute Maximum Ratings
Parameter
V
CC
Voltage
DRIVE Voltage
REF Voltage
VCC, DRIVE, REF Current
Operating Junction Temperature
Lead Temperature (soldering 10 seconds)
Storage Temperature Range
Value
18
18
18
50
150
300
-80 to +150
Units
V
V
V
mA
ºC
ºC
ºC
Electrical Specifications
Electrical characteristics are guaranteed over the full temperature range –40ºC <Tj< 85ºC. Ambient
temperature must be de-rated based upon power dissipation and package thermal characteristics.
Unless otherwise stated, test conditions are V
CC
= 5V, V
DRIVE
= 4.3V, V
GND BIAS
= GND.
Symbol
Vcc
Icc
V
REF
TC
REF
Ln
REG
Ld
REG
I
REF
V
DRV
low
I
DRIVE
I
LEAK
Parameter
Supply Voltage Range
Vcc Quiescent Supply
Current
Reference Voltage
Reference Temperature
Deviation
Output variation with Supply
Voltage
Vref variation with Drive
Current
Reference input current
Output Saturation Voltage
Drive Current
Output Leakage Current
V
REF
= V
CC
= V
DRIVE
= 5V
Ta=25ºC
-40ºC <Tj<85ºC
VCC=2.5V to 18V
I
DRIVE
= 500 µA
I
DRIVE
= 0.1mA to 10 mA
V
REF
= 0V
I
DRIVE
= 10 mA, V
REF
= 0V
V
DRIVE
= 5V,
V
REF
= V
GND BIAS
= GND
V
DRIVE
= V
REF
= V
CC
= 18V
20
-50
1.231
Conditions
Min
2.5
Typ
5
150
1.250
0.5
0.3
0.15
-20
1.8
25
200
400
2.2
Max
18
300
1.268
1
1.0
0.20
Units
V
µA
V
%
mV/V
%/mA
nA
V
mA
nA
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Rev. 1.2
April 1, 2006
Acutechnology Semiconductor Inc.
AQ120
APPLICATION
(Figure 1)
GENERAL DESCRIPTION
The AQ120 is a linear LDO voltage regulator controller. It drives a discrete PNP transistor while
comparing the output to a 1.25V reference. The output voltage is programmable through an external
resistor divider. V
OUT
can be set to any value above 1.25 Volts. The collector of the external PNP
transistor provides the output current to the load. Vin range is 2.5V to 18V. The Maximum Load current
is Beta of the PNP times I
DRIVE
. I
DRIVE
range is 0.1 mA to 20 mA (max).
SETTING THE OUTPUT VOLTAGE
The AQ120 V
REF
pin is the input to an amplifier comparing to a precision 1.25V reference.
With V
REF
tied back to the output, it will drive the base of the external PNP to maintain output voltage
with changing load current and VCC. The regulated output voltage can be set by selecting the proper
ratio of R1 and R2.
The Output Voltage is set by:
Vout
=
V
REF
∗
R
1
+
R
2
=
1.25
V
∗
1
+
R
1
R
2
R
2
(
)
Rev. 1.2
April 1, 2006
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Acutechnology Semiconductor Inc.
SELECTION OF PNP PASS DEVICE
AQ120
In the application of (figure 1) above, an FMMT549 SOT223 package was used.
However, selection of the PNP pass device is based on Vin max, Iout max, and Power dissipation for
your particular application.
V
IN
max
BVCEO and BVCBO minimum rating of the PNP transistor must exceed the maximum Vin of the
application. The AQ120 will stand off 18V max. Therefore the maximum voltage the PNP will
experience is 18V.
Iout max
Beta of the PNP transistor will dictate the maximum output current as per the equation:
Iout
max
=
Idrive
max(20
mA
)
∗
BetaExt
.
PNP
Higher beta of the PNP will improve the Vout variation due to change in load (load reg.) Minimizing the
Idrive required will also minimize the Load reg. as Vout will decrease by .15% per mA of Idrive.
Therefore, delta 10mA of Idrive will cause a delta 1.5% of Vout.
Power dissipation
Selection of the external PNP package is based on size requirements and power dissipation. Consult
the transistor data sheet for power considerations.
Contact Information
Acutechnology Semiconductor Inc.
3487 McKee Rd. Suite 52
San Jose CA , USA 95127
Disclaimer
The information furnished by Acutechnology in this data sheet is believed to be accurate and reliable. However,
Acutechnology assumes no responsibility for its use. Acutechnology reserves the right to change circuitry and specifications
at any time without notification to the customer.
TEL:
FAX:
website:
(408) 259-2300
(408) 259-9160
www.acutechnology.com
Life Support Policy
Acutechnology Products are not designed or authorized for use as components in life support devices or systems where
malfunction of a product can reasonably be expected to result in personal injury. Life support devices or systems are
devices or systems that (a) are intended for surgical implant into the body or (b) support or sustain life, and whose failure to
perform can be reasonably expected to result in a significant injury to the user.
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