ACUTECH AQ8211AY-M5-25-TRL

AQ8211
Ultra-Low Dropout
500mA Voltage Regulator
with Enable
Product Specification
Revision 2.1
General Description
The AQ8211 is an ultra-low dropout voltage
regulator capable of delivering 500 mA to the
load. It is adjustable and can set a precise
voltage from 1.22V to 12V with two external
resistors. The AQ8211 meets all specifications
down to 1.22V output, unlike CMOS LDO’s which
loose performance with outputs below 2.25V.
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. This also allows for a separate bias
connection from the pass transistor in order to
achieve ultra low dropout from VIN to VOUT.
Reverse current protection blocks current
flowing from VOUT to VIN when the AQ8211 is
disabled. No current flows.
To assure accuracy over temperature, the heart
of the AQ8211 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.
January 22, 2007
Applications
• Graphic cards and PC motherboards
• Cell Phones
• DVD video player
Replacement for:
• LX8211
Features
• Extended Temp Range -40C˚ ≤ 125C˚
• Low dropout voltage (350mV at 500 mA)
• Enable pin implements sequencing
• Reverse current protection
• Featured in the very small SOT-23
•
•
•
•
•
package
Stable with low cost 1µF capacitor
Low ground current <100 µA
Thermal protection with hysteresis
Short circuit protection
RoHS compliant
Typical Application
www.acutechnology.com
AQ8211
AQ8211
Acutechnology Semiconductor Inc.
Pin Configuration
Pin Descriptions
Pin Name
VIN
Ground
Function
+ Unregulated Input Voltage, Collector of Pass Transistor
Adjust
- Ground
Active high, ENABLE > (0.95V + VOUT), Chip bias circuit supply
OFF low, ENABLE < 0.25V
Adjust input. Connect to resistive feed back divider.
VOUT
Regulated Output
ENABLE
Functional Block Diagram
www.acutechnology.com
2
Rev. 2.1
January 22, 2006
AQ8211
Acutechnology Semiconductor Inc.
Ordering Information
Device
Operating Tj
%Tol
PKG Type
VOUT
Wrap
Ordering Number
AQ8211
-40C˚ ≤ 125C˚
1.0
SOT-23-5
1.8V
T&R
AQ8211AY-M5-18-TRL
AQ8211
-40C˚ ≤ 125C˚
1.0
SOT-23-5
2.5V
T&R
AQ8211AY-M5-25-TRL
AQ8211
-40C˚ ≤ 125C˚
1.0
SOT-23-5
3.3V
T&R
AQ8211AY-M5-33-TRL
AQ8211
-40C˚ ≤ 125C˚
1.0
SOT-23-5
ADJ
T&R
AQ8211AY-M5-AJ-TRL
Note: The
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
-40C˚ ≤ 125C˚
°C
-65 to 150
°C
300
°C
Power Dissipation (Internally limited)
Maximum Junction Temperature
Operating Junction Temperature Range
Storage Temperature Range
Lead Temperature (Soldering, 4 sec.) SOT- 23-5 package
Thermal Management
Thermal Resistance (Junction to Ambient)
SOT-23-5 (minimum foot print)
Thermal Resistance (Junction to Ambient)
SOT-23-5 (Soldered to 1 in2 1 oz. copper PCB)
www.acutechnology.com
3
Typical
Value
Units
220
°C/W
Typical
Value
Units
170
°C/W
Rev. 2.1
January 22, 2006
AQ8211
Acutechnology Semiconductor Inc.
Electrical Specifications
Electrical characteristics are guaranteed over the full temperature range -40ºC <Tj< 125ºC. Ambient
temperature must be de-rated based upon power dissipation and package thermal characteristics. Unless
otherwise specified: VENABLE = VIN = (VOUT + 1.5V), IOUT = 10 mA, Tj = 25C. 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)
∆VEN = VOUT + (1.5V to 10V)
LDREG
Load Regulation (1)
∆IOUT = (10mA to 250 mA)
0.2
0.4
%
IOUT = 100 mA
50
80
mV
IOUT = 250 mA
150
200
mV
IOUT = 500 mA
300
350
mV
VD
Dropout Voltage (1, 2)
-40°C ≤Tj ≤ 125°C
ISC
Current Limit (1)
IGND
Ground Current ON
IGND
Ground Current ON (5)
Adjustable version
VIL
Enable Pin Voltage (OFF)
With respect to GND
VIH
Enable Pin Voltage (ON)
With respect to VOUT
0.92
0.95
V
IOUT = 10 mA
0.3
0.5
mA
IOUT = 250 mA
1.8
3.0
mA
IOUT = 500 mA
3.8
5.0
mA
1.220
1.232
V
1.238
V
2.0
mA
IENON
Enable Current ON
VADJ
Reference Voltage
IQMIN
Minimum Load Current (5)
TC
Temperature Coefficient
TS
VN
PSRR
TSD
TSDHYST
VEN-VOUT = 2V
600
0.25
Adjustable version only
1.208
-40°C ≤Tj ≤ 125°C
1.202
To maintain regulation
800
mA
100
150
µA
65
100
µA
0.45
0.5
V
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
72
dB
150
°C
25
°C
60
TSD Hysteresis
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
www.acutechnology.com
4
Rev. 2.1
January 22, 2006
AQ8211
Acutechnology Semiconductor Inc.
Application Notes
www.acutechnology.com
5
Rev. 2.1
January 22, 2006
AQ8211
Acutechnology Semiconductor Inc.
Application Notes
1. Typical Application
Notes:
1. Output voltage is 1.22V * (R1 +R2)/R2
2. Input and output capacitors should be located close to the device.
3. The AQ8211 will remain stable with C1 and C3 as low as 0.1 µF and 1.0 µF respectively.
Overall transient performance is improved with increased capacitance and the addition of C2.
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] 500mA) 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 100nF capacitor is a suitable input bypass for
almost all applications. A larger capacitor is also suitable depending on the cleanliness of the
Enable source.
A Vin Capacitor is also recommended. A 1µF capacitor is a bypassing for almost all applications.
A larger capacitor is also suitable depending on the cleanliness of the VIN source.
The Output capacitor is critical in maintaining regular stability. The AQ8211 is stable with an
output capacitor greater than 1µF. Any increase of the output capacitor will merely improve
the loop stability and the load transient response.
Tantalum Capacitors exhibit the best stability over a wide range of loads and are recommended.
3. Output Voltage
The AQ8211 meets all specifications down to 1.22V output. It does not suffer from
performance degradation issues such as experienced with CMOS LDO’s. Drop out voltage
will be less than 350 mV at 500 mA load with the ENABLE pin held greater than 0.95V + Vout.
www.acutechnology.com
6
Rev. 2.1
January 22, 2006
AQ8211
Acutechnology Semiconductor Inc.
The AQ8211 develops a 1.22V reference voltage between the adjust pin terminal and
ground. This voltage is applied across the resistor R2 to generate a constant current (I2). The
current from the adjust terminal could introduce error to the output, but since it is very small
(<0.5µA) compared with the current I2 and very constant with line and load changes, the
error can be ignored. The constant current I2 then flows through resistor R1 and sets the
output voltage to the desired level.
The AQ8211 regulates the voltage that appears between its output and ground pins or
between its adjust and ground 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.
The best performance is obtained with the positive side of the resistor R1 tied near the load
and with the ground side of the resistor R2 tied near the ground of the regulator. This will
provide remote output sensing which will optimize regulation at the load.
4. Enable/Sequencing
The AQ8211 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.
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.
www.acutechnology.com
7
Rev. 2.1
January 22, 2006
AQ8211
Acutechnology Semiconductor Inc.
To this end, the AQ8211 allows for an analog control of the output voltage via the ENABLE pin.
This allows for sequential, ratio-metric and simultaneous sequencing schemes.
5. Protection Diodes
Unlike older regulators, the AQ8211 requires no protection diodes between the ADJ pin and
VOUT or from the VOUT to the VIN to prevent over-stressing the die. Internal resistors are
limiting the internal current paths on the ADJ pin. Therefore, even with capacitors on the ADJ
pin, no protection diode is needed to ensure device safety under short circuit conditions.
External diodes between the VIN and VOUT are not usually needed. Only if high value
output capacitors are used (> 1000uF) and the input is instantaneously shorted to ground,
can damage occur.
6. 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 AQ8211 regulators have internal thermal shutdown to protect the device from overheating. Under all possible operating conditions, the junction temperature of the AQ8211
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 max. 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.
7. Ultra low Dropout Operation
The AQ8211 allows for ultra low dropout operation by connecting the pin ENABLE to >0.95V + Vout.
This results in a dropout of 350 mV at 500 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.
www.acutechnology.com
8
Rev. 2.1
January 22, 2006
AQ8211
Acutechnology Semiconductor Inc.
Package Dimensions
www.acutechnology.com
9
Rev. 2.1
January 22, 2006
AQ8211
Acutechnology Semiconductor Inc.
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.
AcuRef is a trademark of Acutechnology Semiconductor Inc
www.acutechnology.com
10
Rev. 2.1
January 22, 2006