A8405: Low-Dropout Regulators -- High Efficiency

PRELIMINARY INFORMATION
LOW-DROPOUT REGULATORS
— HIGH EFFICIENCY
OUT
BYPASS
OR
ADJ*
(subject to change without notice)
June 25, 1999
5
4
Designed specifically to meet the requirement for extended operation of battery-powered equipment such as cordless and cellular telephones, the A8405SLH voltage regulators offer the reduced dropout
voltage and quiescent current essential for maximum battery life.
Applicable also to palmtop computers and personal data assistants,
these devices deliver a regulated output at up to 200 mA (transient),
which is internally limited, providing short-circuit protection. Regulated output voltages of 2.7, 2.8, 3.0, 3.2, 3.3, 3.6, 3.8, 4.0, and 5.0 V
are currently provided. Other voltages, down to 2.0 volts, are available
on special order.
A PMOS pass element provides a typical dropout voltage of only
100 mV at 100 mA of load current. The low dropout voltage permits
deeper battery discharge before output regulation is lost. Quiescent
current does not increase significantly as the dropout voltage is approached, an ideal feature in standby/resume power systems where data
integrity is crucial. Regulator accuracy and excellent temperature
characteristics are provided by a bandgap reference. The A8405SLH
includes an ENABLE input to give the designer complete control over
power up, standby, or power down.
These devices are supplied in a thermally enhanced 5-lead smalloutline plastic package similar to the SOT-23, and fitting the SC-74A
footprint. All devices are rated for operation over a temperature range
of -20°C to +85°C.
T
C
U
Y
D
L
O
N
R
P EO
D
C
E
N
U
E
N
R
I
E
T
F
N
E
O
R
C
S OR
I
D F
—
2
GND
3
ENABLE
1
IN
VR
Dwg. PS-021-6
*BYPASS (fixed regulators) or
ADJUST (A8405SLH-ADJ only).
Data Sheet
27468.22
8405
FEATURES AND BENEFITS
ABSOLUTE MAXIMUM RATINGS
Input Voltage, VI . . . . . . . . . . . . . . . 7 V
Peak Output Current,
IOM . . . . . . . . . . . . . . . . . . 200 mA*
Enable Input Voltage, VE . . . . . . . . . . VI
Operating Temperature Range,
TA . . . . . . . . . . . . . -20°C to +85°C
Junction Temperature, TJ . . . . +150°C
Storage Temperature Range,
TS . . . . . . . . . . . . -40°C to +150°C
* Output current rating is limited by input
voltage, duty cycle, and ambient temperature.
Under any set of conditions, do not exceed a
junction temperature of +150°C. See following pages.
■
■
■
■
■
■
High Efficiency Provides Extended Battery Life
100 mV Typical Dropout Voltage at IO = 100 mA
80 µA Typical Quiescent Current
Low Output Noise
200 mA Current-Limited Output
Improved PSRR and Transient Performance
APPLICATIONS
■
■
■
■
■
■
Cordless/Cellular/GSM/PHS Telephones
Personal Data Assistants
Personal Communicators
Palmtop Computers
GPS
Pagers
Always order by complete part number, e.g., A8405SLH-xx , where “xx”
is the required output voltage in tenths or “ADJ” for adjustable.
8405
LOW-DROPOUT
REGULATORS
FUNCTIONAL BLOCK DIAGRAM
IN
1
5
OUT
5
OUT
4
BYPASS
ADJUST
4
DRIVE
3
2
ERROR
AMP
OVERCURRENT
PROTECTION
ENABLE
ENABLE
THERMAL
PROTECT.
BIAS
(SUFFIX
"-ADJ" ONLY)
(FIXED REG'S)
BANDGAP
REF.
GND
Dwg. FS-012-7
A8405SLH Maximum Allowable Average Output Current* with device mounted on 2.24" x 2.24"
(56.9 mm x 56.9 mm) solder-coated copper-clad board in still air.
Allowable Total Average (10 ms) Output Current in Milliamperes with TJ = 150°C, Duty Cycle = 100%†
VI - VO
TA
0.5
1.0
1.5
2.0
2.5
3.0
3.5
4.0*
4.5*
25°C
200
200
200
200
200
189
162
142
126
50°C
200
200
200
200
182
152
130
114
101
70°C
200
200
200
182
145
121
104
91
81
85°C
200
200
197
148
118
98
84
74
66
* Absolute maximum peak output current rating is 200 mA; absolute maximum input voltage is 7 V.
† IO = (TJ – TA)/([VI – VO] RθJA x dc) = (150 – TA)/([VI – VO] x 220 x 1.00)
Output current rating can be increased (to 200 mA maximum) by additional heat sinking or reducing the duty cycle.
115 Northeast Cutoff, Box 15036
Worcester, Massachusetts 01615-0036 (508) 853-5000
Copyright © 1999, 2000 Allegro MicroSystems, Inc.
8405
LOW-DROPOUT
REGULATORS
ELECTRICAL CHARACTERISTICS at TA = +25°C, VE ≥ 2.0 V, CBYPASS = TBD (unless otherwise noted).
Limits
Characteristic
Output Voltage
(reference specified VO(nom))
Symbol
Min.
Typ.
Max.
Units
VI ≥ VO(nom) + 1 V, 1 mA ≤ IO ≤ 150 mA*
—
±0.5
—
%
VI ≥ VO(nom) + 1 V, 1 mA ≤ IO ≤ 150 mA*,
over operating temperature range
—
—
±2.0
%
VI = VO(nom), IO = 50 mA
—
—
-0.25
V
VI = 6 V, IO = 10 mA, TJ ≤ 125°C
—
TBD
—
mV/°C
200
—
—
mA
at VI = VO(nom) + 1 V, IO = 3 mA
and VI = 7 V, IO = 3 mA
—
1.0
2.0
mV
at VI = VO(nom) + 1 V, IO = 1 mA
and VI = VO(nom) + 1 V , IO = 150 mA*
—
2.0
—
mV
at VI = 7 V, IO = 1 mA
and VI = 7 V, IO = 150 mA*
—
2.0
—
mV
IO = 100 mA
—
100
—
mV
VI = VO(nom) + 1 V, IO = 1 mA
—
80
100
µA
VI = VO(nom) + 1 V, IO = 150 mA*
—
80
100
µA
VI = 7 V, IO = 1 mA
—
80
100
µA
VI = 7 V, IO = 150 mA*
—
80
100
µA
IQ
VI ≤ 7 V, VE ≤ 0.8 V, IO = 0 mA
—
—
1.0
µA
VEH
VI ≥ VO(nom) + 1 V, Output ON
2.0
—
—
V
VEL
VI ≥ VO(nom) + 1 V, Output OFF
—
—
0.4
V
VE = VI = 7 V
—
—
±1.0
µA
—
1.26
—
V
A8405SLH-ADJ only
—
0.10
—
µA
VI = VO(nom) + 1.5 V, Vi = 100 mV,
IO = 30 mA, f = 60 Hz
—
70
—
dB
10 Hz ≤ f ≤ 100 kHz, IO = 10 mA, CO = 10 µF
—
0.2
—
µV/√Hz
—
170
—
°C
VO
Output Volt. Temp. Coeff.
aVO
Output Short-Circuit Current
IOM
Line Regulation
Load Regulation
Dropout Voltage
Ground Terminal Current
ENABLE Input Voltage
ENABLE Input Current
∆VO(∆VI)
∆VO(∆IO)
VImin - VO
IGND
IE
Internal Reference Voltage
VREF
ADJUST Input Current
IADJ
Rejection Ratio
PSRR
Output Noise
en
Thermal Shutdown
TJ
Test Conditions
Typical values are at TA = +25°C and are given for circuit design information only.
* Pulse test (≤20 ms). See previous page for duty cycle limitations.
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8405
LOW-DROPOUT
REGULATORS
APPLICATIONS INFORMATION
Linear regulators require input and output capacitors in order to
maintain over-all loop stability. The recommended minimum
value for the input capacitor is 0.1 µF. The output capacitor is
the dominant pole that provides the high-frequency compensation required for over-all regulator loop stability. These devices
are stable with as little as 1 µF. However, to ensure stable
operation under all conditions and capacitor types, the recommended minimum value is 4.7 µF. The output capacitor may be
partially distributed through the load circuits. However, at least
1 µF should be connected at the regulator using the shortest and
widest foil pattern possible.
The A8405SLH-ADJ requires an external voltage divider to set
up the desired regulated output voltage between 2.0 V and 6.8 V
(VI ≤ 7 V). The two resistors are chosen such that
VO = 1.26 (R1 + R2)/R2.
The resistor values are usually as high as possible to maintain
high circuit efficiency, but R2 should be less than 300 kΩ.
OUTPUT (2.0 V TO 6.8 V)
5
1
INPUT
(7.0 V MAX)
VR
R1
4
3
ENABLE
(ACTIVE HIGH)
2
0.1 µF
(MIN)
1 µF
(MIN)
R2
(300 kΩ MAX)
Dwg. ES-015
Thermal Considerations
These devices are intended to provide more than 150 mA of
continuous current in a very small package. The table on page 2
of this data sheet gives the maximum allowable average output
current for a worst-case printed circuit design (RθJA = 220°C/W
with a minimum footprint). Performance improvement is easily
accomplished with the addition of 1 square inch of copper at
terminal 2 (RθJA = 170°C/W).
115 Northeast Cutoff, Box 15036
Worcester, Massachusetts 01615-0036 (508) 853-5000
8405
LOW-DROPOUT
REGULATORS
Dimensions in Inches
(for reference only)
0.122
0.079
0.018
0.012
0.028
0.083
0.073
5
1
0.0079
0.0059
4
2
3
0.118
0.106
4
5
0.039
0.022
0° TO 8°
REF
0.037
0.095
1
0.0098 MIN
2
BSC
3
0.037
0.043
0.035
0.049
0.035
0.0059
0.00
Dwg. MA-010-15 in
Dwg. MA-011-5 in
Dimensions in Millimeters
(controlling dimensions)
3.10
2.90
0.45
0.30
0.70
5
2.10
1.85
5
1
0.20
0.15
4
2
3
3.00
2.70
4
0.55
1.00
0° TO 8°
REF
0.95
2.40
1
0.25 MIN
2
BSC
3
0.95
0.15
0.00
1.10
0.90
1.25
0.90
Dwg. MA-011-5 mm
NOTES: 1. Tolerances on package height and width represent allowable mold offsets.
Dimensions given are measured at the widest point (parting line).
2. Exact body and lead configuration at vendor’s option within limits shown.
3. Height does not include mold gate flash.
4. Where no tolerance is specified, dimension is nominal.
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Dwg. MA-010-15 mm
8405
LOW-DROPOUT
REGULATORS
This page intentionally left blank
115 Northeast Cutoff, Box 15036
Worcester, Massachusetts 01615-0036 (508) 853-5000
8405
LOW-DROPOUT
REGULATORS
This page intentionally left blank
www.allegromicro.com
8405
LOW-DROPOUT
REGULATORS
Allegro MicroSystems, Inc. reserves the right to make, from
time to time, such departures from the detail specifications as
may be required to permit improvements in the design of its
products.
The information included herein is believed to be accurate and
reliable. However, Allegro MicroSystems, Inc. assumes no
responsibility for its use; nor for any infringements of patents or
other rights of third parties which may result from its use.
115 Northeast Cutoff, Box 15036
Worcester, Massachusetts 01615-0036 (508) 853-5000
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