AS8863
120 mA, Low Dropout Voltage Regulator
(Preliminary Information)
FEATURES
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•
•
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Low Noise Output LDO
1% Initial Accuracy At 120mA
Very Low Quiescent Current
Low Dropout Voltage
Current & Thermal Limiting
Reverse-Battery Protection
Wide Range of Fix Output Voltages
1.8V, 2.5V, 2.8V, 3.0V, 3.3V, 4.0V, 4.5V, 5.0V, & ADJ
Zero Off-Mode Current
Small 5-Pin SOT-23
Pin Compatible to MAX8863
APPLICATIONS
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PDA
Battery Powered Systems
Cellular Phone
Cordless Telephones
Radio Control Systems
Portable/Palm Top/Notebook Computers
Portable Consumer Equipment
Portable Instrumentation
Bar Code Scanners
SMPS Post-Regulator
PRODUCT DESCRIPTION
The AS8863 is a low-power positive voltage regulator with ultra low noise output and very low dropout voltage. In addition, this
device offers very low quiescent current of approximately 600uA at 100mA output. The AS8863 initial tolerance is less than 1% max
and has a logic compatible ON/OFF switching input. The unique features of the AS8863 include a reference bypass pin for the best
performance results of low noise.
This device is an excellent choice for use in battery powered applications such as cellular/ cordless telephones, radio control systems,
and portable computers. When disabled power consumption drops to nearly zero. The device also has a very low output temperature
coefficient, making it a low power voltage reference. The AS8863 key features include protection against reversed battery, fold-back
current limiting, and automotive load dump protection.
The AS8863 is available in many fixed voltages (1.8V, 2.5V, 2.8V, 3.0V, 3.3V, 4.0V, 4.5V, & 5.0V) or with an adjustable output.
This device is offered in a small 5-pin SOT-23 package. Providing a small footprint with all the performance features with fixed or
adjustable output.
ORDERING INFORMATION
Part Number
AS8863M5-X
Operating Junction
Temperature Range
-40°C to +125°C
Accuracy
1%
Package
Type
SOT-23-5
BYP
5
PIN CONNECTIONS
SOT-23-5 (M5)
V
OUT
4
2
3
X = Output Voltage, 3.0 for 3.0V, 3.3 for 3.3V etc, Blank for Adjustable
For other fixed voltages consult factory.
SOT-23-5 (M5)
ADJ
5
V
OUT
4
2
3
MARKING INFORMATION
Voltage
1.8
2.5
2.8
3.0
3.3
Marking
9WXX
9XXX
9YXX
A3XX
A2XX
Voltage
4.5
4.70
5.0
ADJ
Marking
A4XX
A5XX
A6XX
A7XX
AS8863
1
AS8863
1
EN GND V
IN
EN GND V
IN
Top View
Fixed Output Voltage
Top View
Adjustable Output Voltage
Rev. 10/6/00
AS8863
ABSOLUTE MAXIMUM RATINGS
Power Dissipation...................................... Internally Limited
Lead Temp. (Soldering, 5 Seconds) ............................ 260°C
Operating Junction Temperature Range ..... -40°C to +125°C
Input Supply Voltage........................................-20V to +20V
Enable Input Voltage........................................-20V to +20V
RECOMMENDED OPERATING CONDITIONS
Input Voltage.................................................. +2.5V to+16V
Operating Junction Temperature Range ..... -40°C to +125°C
Enable Input Voltage............................................. 0V to V
IN
SOT-23-5 (θ
JA
) ..................................................... See Note 1
ELECTRICAL CHARACTERISTICS
T
J
= 25°C, V
IN
= V
OUT
+ 1V, I
L
= 100µA, C
L
= 1.0µF, and V
ENABLE
> 2.4V. Unless otherwise specified
boldface
applies over the
junction temperature range
Parameter
Test Conditions
Typ
Min
Max
Units
Output Voltage Tolerance (V
OUT
)
Output Voltage Temperature Coef
Line Regulation
Load Regulation
Dropout Voltage (See Note 2)
(V
IN
- V
O
)
Quiescent Current (I
GND
)
Ground Pin Current
(I
GND
)
Ripple Rejection (PSRR)
Current Limit (I
LIMIT
)
Output Noise (e
NO
)
Input Voltage Level
Logic Low (V
IL
)
Input Voltage Level
Logic High (V
IH
)
ENABLE Input Current
I
L
= 100µA
I
L
= 500µA
V
IN
= V
OUT
+ 1V to 16V
V
IN
= V
OUT
+ 1V to 16V
I
L
= 0.1mA to 120mA
I
L
= 0.1mA to 120mA
I
L
= 100
µA
I
L
= 50mA
I
L
= 120mA
V
ENABLE
< 0.6V
V
ENABLE
< 0.25V
I
L
= 100
µA
I
L
= 50 mA
I
L
= 120mA
V
OUT
= 0V
I
L
= 50mA, C
L
= 1.0µF
(10Hz – 100KHz)
OFF
ON
V
IL
< 0.6V
V
IH
> 2.0V
2.0
0.01
2
2
20
µA
40
0.03
0.1
30
140
190
<1
80
350
950
55
360
390
0.6
-1
-2
+1
+2
0.1
0.2
0.2
0.5
50
190
260
1
5
125
600
1600
320
%V
NOM
ppm/°C
%/V
%
mV
µA
µA
dB
mA
µV
RMS
V
Note 1: The maximum allowable power dissipation is a function of maximum operating junction temperature, T
J (max)
, the junction to ambient thermal resistance, and
the ambient,
θ
JA
, and the ambient temperature T
A
. The maximum allowable power dissipation at any ambient temperature is given:
P
D (max)
= (T
J(max)
- T
A
)
θ
JA
. Exceeding the maximum allowable power limit will result in excessive die temperature; thus, the regulator will go into thermal shutdown.
The
θ
JA
of the AS8863 is 220
o
C/W mounted on a PC board.
Note 2: Not apply to 1.8V version.
Rev. 10/6/00
AS8863
TYPICAL APPLICATION
V
IN
3
4
V
OUT
+
+
GND
2
AS8863
1.0uF
EN
1
5
BYP
(Optn)
ENABLE
may be tied directly to V
IN
Rev. 10/6/00
AS8863
Application Hints
The AS8863 requires an output capacitor for device stability.
The value required varies greatly depending upon the
application circuit and other factors. The high frequency
characteristics of electrolytic capacitors depend greatly on the
type and also on the manufacturer. Sometimes bench testing is
the only means to determine the proper capacitor type and
value. The high quality 2.2µF aluminum electrolytic capacitor
covers all general application circuits, this stability can be
obtained with a tantalum electrolytic value of 1µF.
In general, linear regulator stability decreases with higher
output currents. In some applications the AS8863 may
operate at few milliamps. In these applications the output
capacitance can be further reduced. For example, when the
regulator is running at 10mA output current the output
capacitance value is half compared to the same regulator
that is running at 150mA.
With the AS8863 adjustable regulator, the minimum value
of output capacitance is a function of the output voltage.
The value decreases with higher output voltages, since the
closed loop gain is increased.
Typical Applications Circuits
The AS8863 provides access to the internal reference. A 10µF capacitor on the BYP pin will provide a significant reduction in output
noise. This pin may be left unconnected if the output noise is not a major concern. The AS8863 start-up speed is inversely
proportional to the size of its capacitor. Applications requiring a slow ramp-up of output voltage should consider larger values of
C
BYP
. If the rapid turn-ON is necessary, omit bypass capacitor.
Figure 1 shows AS8863 standard application circuit. The EN (enable) pin is pulled high (>2.0V) to enable the regulator. To disable
the regulator, EN < 0.6V.
V
IN
GND
EN
Hi-ON
Lo-OFF
V
OUT
+
AS8863
5 BYP
(Optn)
3
2
1
+
4
Top View
Fig. 1
The AS8863 in figure 2 shows adjustable output voltage configuration. Two resistors set the output voltage. The formula for output
voltage is:
V
OUT
= 1.235V x (1+ R1)
R2
Resistor values are not critical as the Adj. pin has high input impedance, for best results use resistors of 47kΩ or less. A capacitor for
Adj to ground will provide improved noise performance.
V
IN
+
GND
EN
Hi-ON
Lo-OFF
3
2
1
AS8863
5 ADJ
R2
4
R1
+
V
OUT
Byp
(Optn)
Top View
Fig. 2
Rev. 10/6/00
AS8863
Dropout Voltage Vs. Load Current
110
200
100
90
150
I Gnd (uA)
80
70
60
50
40
0
0
20
40
60
IL ( mA)
80
100
120
30
4
6
8
10
Vin (V)
12
14
16
Vo = 3.3V
IL = 100uA
CL = 1uF
Ground Current Vs. Input Voltage
100
Vin = 4.3V
Vo = 3.3V
CL = 1uF
50
Ground Current Vs. Load Current
(in Dropout)
3.330
1.50
3.325
3.320
1.00
3.315
3.310
3.305
0.50
3.3V Device
Vin = 4.3V
CL = 1uF
Output Voltage Vs. Input Voltage
3.3V Device
IL = 100uA
CL = 1uF
3.300
3.295
3.290
120
4
6
8
10
Vin (V)
12
14
16
0.00
0
20
40
60
IL (mA)
80
100
Dropout Voltage Vs. Load Current
3.310
200
3.308
150
3.306
100
Vin = 4.3V
Vo = 3.3V
CL = 1uF
Output Voltage Vs. Load Current
3.3V Device
Vin = 4.3V
CL = 1uF
3.304
3.302
3.300
0
20
40
60
IL ( mA)
80
100
120
0
20
40
60
IL ( mA)
80
100
120
50
0
Rev. 10/6/00
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