ACUTECH AQ112CY-S4-33-TR

AQ112
Ultra-Low Dropout
1A Voltage Regulator
Product Specification
Revision 1.6
General Description
The AQ112 is an ultra-low dropout three terminal
voltage regulator, offered in popular fixed options
or an adjustable version that can set a precise
voltage from 1.22V to 12V with two external
resistors.
It drops into the footprint of the popular LM1117
SOT-223 and provides a true 4th pin separated
from the output tab which allows a separate bias
connection from the pass transistor in order to
achieve enable and ultra low dropout from VIN
to VOUT.
The enable pin provides a remote turn-off for low
power consumption. It draws virtually zero current
in shutdown mode and implements Sequential,
Ratiometric,
or
Simultaneous
sequencing
schemes.
To assure accuracy within 1%, the heart of the
AQ112 is a self-correcting AcuRef™ bandgap
reference.
On-chip current limit and thermal shutdown with
hysteresis protects against any combination of
overload and ambient temperature that might
cause the junction temperature to exceed safe
limits.
September 13, 2006
Applications
• Graphic cards
• PC motherboards
• Switching power supply post-regulation
• Telecom equipment
• DVD video player
Features
• Ultra Low Dropout (400mV at 1A)
• Enable pin implements sequencing
• Vout tolerance less than 1.5% over
•
•
•
•
•
•
temperature
Stable with low cost 1uF capacitor
Thermal protection with hysteresis
Short circuit protection
Adjustable output
The AQ112 is featured in the new
SOT223 4-lead TetraPackTM package.
RoHS compliant available
Typical Application
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AQ112
AQ112
Acutechnology Semiconductor Inc.
Pin Configuration
Pin Descriptions
Pin Name
VIN
ENABLE
Ground/Adjust
VOUT
Function
+ Unregulated Input Voltage, Collector of Pass Transistor
Active high, ENABLE > (0.95V + VOUT), Chip bias circuit supply
OFF low, ENABLE < 0.25V
Ground or Adjust pin (Connect to resistive feed back divider)
Regulated Output
Functional Block Diagram
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Ordering Information
Device
Operating Tj
%Tol
PKG Type
VOUT
Wrap
AQ112
0C˚ ≤ 125C˚
1.0
SOT-223-4
1.8V
T&R
AQ112CY-S4-18-TR
AQ112
0C˚ ≤ 125C˚
1.0
SOT-223-4
1.8V
T&R
AQ112CY-S4-18-TRL
AQ112
0C˚ ≤ 125C˚
1.0
SOT-223-4
2.5V
T&R
AQ112CY-S4-25-TR
AQ112
0C˚ ≤ 125C˚
1.0
SOT-223-4
2.5V
T&R
AQ112CY-S4-25-TRL
AQ112
0C˚ ≤ 125C˚
1.0
SOT-223-4
3.3V
T&R
AQ112CY-S4-33-TR
AQ112
0C˚ ≤ 125C˚
1.0
SOT-223-4
3.3V
T&R
AQ112CY-S4-33-TRL
AQ112
0C˚ ≤ 125C˚
1.0
SOT-223-4
ADJ
T&R
AQ112CY-S4-AJ-TR
AQ112
0C˚ ≤ 125C˚
1.0
SOT-223-4
ADJ
T&R
AQ112CY-S4-AJ-TRL
Note: The
Ordering Number
TRL parts are Lead Free and RoHS compliant.
Absolute Maximum Ratings
Stress greater than those listed under “Absolute Maximum Ratings” may cause permanent damage to the
device. These stress ratings only, and functional operation of the device at these or any conditions beyond
those indicated under recommended Operating Conditions is not implied. Exposure to “Absolute Maximum
Rating” for extended periods may affect device reliability. Use of standard ESD handling precautions is
required.
Parameter
Value
Units
Maximum VIN
18
Volts
Maximum VENABLE
18
Volts
150
°C
0 to 125
°C
-65 to 150
°C
300
°C
Typical Value
Units
15
°C/W
Typical Value
Units
46
°C/W
Power Dissipation (Internally limited)
Maximum Junction Temperature
Operating Junction Temperature Range
Storage Temperature Range
Lead Temperature (Soldering, 4sec.) SOT- 223 package
Thermal Management
Thermal Resistance (Junction to TAB)
SOT-223
Thermal Resistance (Junction to Ambient)
SOT-223 (tab soldered to 1 in2 1 oz. copper PCB)
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Electrical Specifications
Electrical characteristics are guaranteed over the full temperature range 0ºC <Tj< 125ºC. Ambient temperature
must be de-rated based upon power dissipation and package thermal characteristics. Unless otherwise
specified: VIN = VEN = (VOUT + 1.5V), IOUT = 10 mA, Tj = 25C. All values in bold are over the full temperature
range.
Symbol
Parameter
Conditions
Min
Typ
Max
Units
-1
VOUT
+1
%
-1.5
VOUT
+1.5
%
0.035
0.2
%
VOUT
Output Voltage (1)
LNREG
Line Regulation (1)
∆VIN = VOUT + (1.5V to 10V)
LDREG
Load Regulation (1)
∆IOUT = (10mA to 1 Amp)
0.2
0.4
%
IOUT = 100 mA
50
80
mV
IOUT = 500 mA
200
250
mV
IOUT = 1A
350
400
mV
VD
ISC
Drop out Voltage (1, 2)
Current Limit (1)
0°C ≤Tj ≤ 125°C
VEN-VOUT = 2V
1.1
VEN = 5V
1.5
7.0
A
9.0
mA
10.0
mA
IQ
Quiescent Current
VIL
Enable Pin Voltage (OFF)
With respect to GND
VIH
Enable Pin Voltage (ON)
With respect to VOUT
0.92
0.95
V
Enable Current ON
IOUT = 10 mA
0.3
0.5
mA
IOUT = 500 mA
2.5
5.0
mA
IOUT = 1A
5.0
10.0
mA
1.220
1.232
V
1.238
V
20
40
µA
IENON
0°C ≤Tj ≤ 125°C
0.25
Note (5)
1.208
0°C ≤Tj ≤ 125°C
1.202
0.45
V
VADJ
Reference Voltage
IADJ
Adjust Pin Current (5)
∆ IADJ
Adjust Pin Current (5)
Change
10mA ≤ IOUT≤ 1Amp
1.4 ≤ VIN ≤ 18V
0.2
5.0
µA
Minimum Load Current (5)
To Maintain regulation
0.5
2.0
mA
IQMIN
TC
Temperature Coefficient
TS
VN
PSRR
TSD
TSDHYST
0.005
%/°C
Temperature Stability
0.5
RMS Output Noise (3)
0.003
%/°C
%
VOUT
Ripple Rejection Ratio (4)
Vin = 5V
Thermal Shutdown
Junction Temperature
60
TSD Hysteresis
72
dB
150
°C
25
°C
Notes: (1) Low duty cycle pulse testing with Kelvin connections required.
(2) Measure (VIN - VOUT) when ∆VOUT, OR ∆VREF = 1%
(3) Bandwidth of 10Hz to 10kHz
(4) 120Hz input ripple
(5) Adjustable version only
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Typical Response Curves
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Application Notes
1. Typical Application
Notes:
1. Output voltage is 1.22V * (R2 +R1)/R1
2. Input and output capacitors should be located close to the device.
3. The AQ112 will remain stable with C1 and C2 as low as 1.0 µF.
Overall transient performance is improved with increased capacitance and the addition of C3.
4. The output is fully enabled when Enable is 950 mV above the expected VOUT. EN may
be driven by either a digital or analog signal to control either turn-on time or to give full
control of risetime.
5. Enable, tied to any separate source >0.95V + VOUT, will insure Ultra-low drop out voltage
([email protected] 1A) from VIN to VOUT. Or, Enable, tied to Vin will support a low drop out
voltage (0.95V).
2. Stability
An Enable capacitor is recommended. A 1.0 µF capacitor on VIN is a suitable input bypass
for almost all applications. A larger capacitor is also suitable.
In the adjustable version the “adjust” terminal can be bypassed to ground with a bypass
capacitor (CADJ) to improve ripple rejection. This bypass capacitor prevents ripple from being
amplified as the output voltage is increased. At any ripple frequency, the impedance of the
CADJ should be less than R1 (being R1 the resistor between the output and the adjust pin) to
prevent the ripple from being amplified:
Z = 1/(2π*fRIPPLE* CADJ) < R1
R1 is normally in the range of 1KΩ.
The output capacitor is critical in maintaining regular stability. The AQ1541 is stable with an
output capacitor greater than 1.0 µF. Of course any increase of the output capacitor will
merely improve the loop stability and the load transient response. In the case of the
adjustable regulator, when the CADJ is used, a larger output capacitance may be required.
The capacitor C3 may also be necessary if large ripple is present on the VIN line. Tantalum
Capacitors exhibit the best stability over a wide range of loads and are recommended.
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AQ112
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3. Output Voltage
The AQ112 adjustable version develops a 1.22V reference voltage between the output and
the adjust pin terminal. This voltage is applied across the resistor R1 to generate a constant
current (I1). The current from the adjust terminal could introduce error to the output, but since
it is very small (< 20µA) compared with the current I1 and very constant with line and load
changes, the error can be ignored. The constant current I1 then flows through resistor R2
and sets the output voltage to the desired level.
For fixed voltages the resistor R1 and R2 are integrated inside the devices.
The AQ112 regulates the voltage that appears between its output and ground pins or
between its output and adjust pins. In some cases, line resistances can introduce errors to
the voltage across the load. To obtain the best load regulation a few precautions are needed.
For example it is important to minimize the line resistances to the load, so the load itself
should be tied directly to the output terminal on the positive side and directly to the ground
terminal on the negative side.
When the adjustable regulator is used, the best performance is obtained with the positive
side of the resistor R1 tied directly to the output terminal of the regulator rather than near the
load. This will eliminate line drops from appearing effectively in series with the reference and
degrading regulation. In addition the ground side of the resistor R2 can be returned near the
ground of the load to provide remote ground sensing and improve load regulation. A
capacitor (470pF) between the ADJ pin and system ground will enhance stability.
4. Enable/Sequencing
The AQ112 provides an enable function. The EN pin has to be at least 950 mV higher than
the output voltage for the device to be fully turned on. When the voltage of the EN pin is low
the device is in shutdown mode and it will not draw any current from the VIN terminal.
ENABLE
OUT
0
FIG.2 ENABLE 0-5V, Output follows to 3.3V out
(1V/div vertical, 200us/div horizontal)
In addition the enable function includes a sequencing feature, because when the enable pin
ramps in voltage the output voltage follows (it will be around 900 mV less than the enable
voltage until it reaches the regulation voltage) as shown in Fig. 2 above.
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In applications where multiple regulated supply rails are required, it is often required that the
relationship between the various supply voltages be controlled during start-up and shutdown.
To this end, the AQ112 allows for an analog control of the output voltage via the ENABLE pin.
This allows for sequential, ratio-metric and simultaneous sequencing schemes.
4. Protection Diodes
Unlike older regulators, the AQ112 family does not need any protection diodes between the
adjustment pin and output or from the output to the input to prevent over-stressing the die.
Internal resistors are limiting the internal current paths on the adjustment pin. Therefore,
even with capacitors on the adjustment pin, no protection diode is needed to ensure device
safety under short circuit conditions. External diodes between the input and output are not
usually needed. Only if high value output capacitors are used (> 1000uF) and the input is
instantaneously shorted to ground, can damage occur.
5. Thermal Considerations
When an integrated circuit operates with an appreciable current, its junction temperature is
elevated. It is important to quantify its thermal limits in order to achieve acceptable
performance and reliability. This limit is determined by summing the individual parts
consisting of a series of temperature rises from the semiconductor junction to the operating
environment. The heat generated at the device junction flows through the die to the die
attach pad, through the lead frame to the surrounding case material, to the printed circuit
board, and eventually to the ambient environment.
The AQ112 regulators have internal thermal shutdown to protect the device from overheating. Under all possible operating conditions, the junction temperature of the AQ112
must be lower than 125°C. A heatsink may be required depending on the maximum power
dissipation and maximum ambient temperature of the application.
To determine if a heatsink is needed, the power dissipated by the regulator, PD, must be
calculated:
PD= (VC-VOUT) IL
where the IL is the load current.
The next parameter which must be calculated is the maximum allowable temperature rise,
T(max):
T(max)=TJ(max)-TA(max)
where TJ(max) is the maximum allowable junction temperature (125°C), and TA(max) is the
maximum ambient temperature which will be encountered in the application.
Using the calculated values for T(max) and PD, the maximum allowable value for the
junction to ambient thermal resistance (θJA) can be calculated:
θJA=T(max)/ PD
If the maximum allowable value for θJA is found to be greater than the junction to
ambient thermal resistance for the package used, no heatsink is needed since the
package alone will dissipate enough heat to satisfy these requirements.
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AQ112
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7. Ultra low Dropout Operation
The AQ112 allows for ultra low dropout operation by connecting the pin ENABLE to >0.95V + Vout.
This results in a dropout of 100 mV at 150 mA of load current, between Vin and VOUT.
This feature is important when the supply voltage is dropping near the output regulated voltage.
Furthermore if the voltage dropout is low, the internal power dissipation is also reduced and the
thermal requirements of the device are less stringent.
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Package Dimensions
SOT223-4 TetraPackTM
Contact Information
Acutechnology Semiconductor Inc.
3487 McKee Rd. Suite 52
San Jose CA , USA 95127
TEL:
FAX:
website:
(408) 259-2300
(408) 259-9160
www.acutechnology.com
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.
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.
TetraPack and AcuRef are trademarks of Acutechnology Semiconductor Inc
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