ACUTECH BQ8211

BQ8211
Low Dropout
300mA Voltage Regulator
with Enable
Product Specification
Revision 1.3
General Description
The BQ8211 is a low dropout voltage regulator
capable of delivering 300 mA to the load. It is
adjustable and can set a precise voltage from
1.175V to 15V with two external resistors. The
BQ8211 meets all specifications down to 1.175V
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
while in shutdown mode.
To assure accuracy within 2% over temperature,
the heart of the BQ8211 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 and PC motherboards
• Cell Phones
• DVD video player
Replacement for:
• LX8211
Features
• Low dropout voltage (980mV at 300 mA)
• Enable pin implements sequencing
• Vout tolerance less than 2 % over
•
•
•
•
•
•
temperature
Featured in the very small SOT-23
package
Stable with low cost 1µF capacitor
Low ground current
Thermal protection with hysteresis
Short circuit protection
RoHS compliant available
Typical Application
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BQ8211
BQ8211
Acutechnology Semiconductor Inc.
Pin Configuration
Pin Descriptions
Pin Name
VIN
Ground
Function
+ Unregulated Input Voltage, Collector of Pass Transistor
Adjust
- Ground
Active high, ENABLE > 1 V
OFF low, ENABLE < 0.25V
Adjust input. Connect to resistive feed back divider.
VOUT
Regulated Output
ENABLE
Functional Block Diagram
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Acutechnology Semiconductor Inc.
Ordering Information
Device
Operating Tj
%Tol
PKG Type
VOUT
Wrap
BQ8211
0C˚ ≤ 125C˚
1.0
SOT-23-5
1.8V
T&R
BQ8211CY-M5-18-TR
BQ8211
0C˚ ≤ 125C˚
1.0
SOT-23-5
1.8V
T&R
BQ8211CY-M5-18-TRL
BQ8211
0C˚ ≤ 125C˚
1.0
SOT-23-5
2.5V
T&R
BQ8211CY-M5-25-TR
BQ8211
0C˚ ≤ 125C˚
1.0
SOT-23-5
2.5V
T&R
BQ8211CY-M5-25-TRL
BQ8211
0C˚ ≤ 125C˚
1.0
SOT-23-5
3.3V
T&R
BQ8211CY-M5-33-TR
BQ8211
0C˚ ≤ 125C˚
1.0
SOT-23-5
3.3V
T&R
BQ8211CY-M5-33-TRL
BQ8211
0C˚ ≤ 125C˚
1.0
SOT-23-5
ADJ
T&R
BQ8211CY-M5-AJ-TR
BQ8211
0C˚ ≤ 125C˚
1.0
SOT-23-5
ADJ
T&R
BQ8211CY-M5-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
18
Volts
Vin + 0.3V
Volts
150
°C
Operating Junction Temperature Range
-40 to 125
°C
Storage Temperature Range
-65 to 150
°C
300
°C
Typical
Value
Units
220
°C/W
Typical
Value
Units
170
°C/W
Maximum VIN
Maximum VENABLE
Power Dissipation (Internally limited)
Maximum Junction Temperature
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)
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BQ8211
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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 = 1V, 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
%
-2.0
VOUT
+2.0
%
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 300 mA)
0.2
0.4
%
IOUT = 100 mA
0.93
1.0
V
IOUT = 150 mA
0.94
1.0
V
IOUT = 300 mA
0.98
1.1
V
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
VIH
Enable Pin Voltage (ON)
With respect to GND
VIL
Enable Pin Voltage (OFF)
With respect to GND
IENON
Enable Current ON
VENABLE = VIN = 5V
VADJ
Reference Voltage
IQMIN
Minimum Load Current (5)
TC
Temperature Coefficient
TS
VN
PSRR
TSD
TSDHYST
VEN-VOUT = 2V
500
0.25
Adjustable version only
1.163
0°C ≤Tj ≤ 125°C
1.151
To maintain regulation
800
mA
100
150
µA
65
100
µA
0.92
1.0
V
0.45
V
60
100
µA
1.175
1.187
V
1.199
V
2.0
mA
0.5
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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Rev. 1.3 September 13, 2006
BQ8211
Acutechnology Semiconductor Inc.
Application Notes
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Rev. 1.3 September 13, 2006
BQ8211
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Application Notes
1. Typical Application
Notes:
1. Output voltage is 1.175V * (R1 +R2)/R2
2. Input and output capacitors should be located close to the device.
3. The BQ8211 will remain stable with C2 and C3 as low as 1.0 µF.
Overall transient performance is improved with increased capacitance.
4. The output is fully enabled when Enable is above 1V. EN may be driven by either a digital
or analog signal to control turn-on time.
2. Stability
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 BQ8211 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.
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BQ8211
Acutechnology Semiconductor Inc.
3. Output Voltage
The BQ8211 meets all specifications down to 1.175V output. It does not suffer from
performance degradation issues such as experienced with CMOS LDO’s.
The BQ8211 develops a 1.175V 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 BQ8211 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 BQ8211 provides an enable function. The EN pin has to be at least 1V 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.
5. Protection Diodes
Unlike older regulators, the BQ8211 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.
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Rev. 1.3 September 13, 2006
BQ8211
Acutechnology Semiconductor Inc.
The BQ8211 regulators have internal thermal shutdown to protect the device from overheating. Under all possible operating conditions, the junction temperature of the BQ8211
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.
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
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Rev. 1.3 September 13, 2006
BQ8211
Acutechnology Semiconductor Inc.
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Rev. 1.3 September 13, 2006