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8405
PRELIMINARY INFORMATION
(subject to change without notice) June 25, 1999
BYPASS OR ADJ*
Data Sheet 27468.22
LOW-DROPOUT REGULATORS -- HIGH EFFICIENCY
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, 3.3, 3.6, 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 -20C to +85C.
OUT
5
4
VR
1
2
3
Dwg. PS-021-6
*BYPASS (fixed regulators) or ADJUST (A8405SLH-ADJ only).
ENABLE
GND
IN
FEATURES AND BENEFITS
s s s s s s s s s s s s High Efficiency Provides Extended Battery Life 100 mV Typical Dropout Voltage at IO = 100 mA 80 A Typical Quiescent Current Low Output Noise 200 mA Current-Limited Output Improved PSRR and Transient Performance Cordless/Cellular/GSM/PHS Telephones Personal Data Assistants Personal Communicators Palmtop Computers GPS Pagers
ABSOLUTE MAXIMUM RATINGS
Input Voltage, VI . . . . . . . . . . . . . . . 7 V Peak Output Current, IOM . . . . . . . . . . . . . . . . . . 200 mA* Enable Input Voltage, VE . . . . . . . . . . VI Operating Temperature Range, TA . . . . . . . . . . . . . -20C to +85C Junction Temperature, TJ . . . . +150C Storage Temperature Range, TS . . . . . . . . . . . . -40C to +150C
* 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 +150C. See following pages.
APPLICATIONS
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 ADJUST
5
OUT
4
BIAS
DRIVE
ERROR AMP
(SUFFIX "-ADJ" ONLY)
4
BYPASS
(FIXED REG'S)
ENABLE
3
OVERCURRENT PROTECTION
THERMAL PROTECT.
ENABLE
BANDGAP REF.
2
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 = 150C, Duty Cycle = 100% VI - VO TA 25C 50C 70C 85C 0.5 200 200 200 200 1.0 200 200 200 200 1.5 200 200 200 197 2.0 200 200 182 148 2.5 200 182 145 118 3.0 189 152 121 98 3.5 162 130 104 84 4.0* 142 114 91 74 4.5* 126 101 81 66
*Absolute maximum peak output current rating is 200 mA; absolute maximum input voltage is 7 V. IO = (TJ - TA)/([VI - VO] RJA 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 (c) 1999, Allegro MicroSystems, Inc.
8405 LOW-DROPOUT REGULATORS
ELECTRICAL CHARACTERISTICS at TA = +25C, VE 2.0 V, CBYPASS = TBD (unless otherwise noted).
Limits Characteristic Output Voltage (reference specified VO(nom)) Symbol VO Test Conditions VI VO(nom) + 1 V, 1 mA IO 150 mA* VI VO(nom) + 1 V, 1 mA IO 150 mA*, over operating temperature range VI = VO(nom), IO = 50 mA Output Volt. Temp. Coeff. Output Short-Circuit Current Line Regulation Load Regulation aVO IOM V O(VI) V O(IO) at VI = VO(nom) + 1 V, IO = 3 mA and VI = 7 V, IO = 3 mA at VI = VO(nom) + 1 V, IO = 1 mA and VI = VO(nom) + 1 V , I O = 150 mA* at VI = 7 V, IO = 1 mA and VI = 7 V, IO = 150 mA* Dropout Voltage Ground Terminal Current VImin - VO IGND IO = 100 mA VI = VO(nom) + 1 V, IO = 1 mA VI = VO(nom) + 1 V, IO = 150 mA* VI = 7 V, IO = 1 mA VI = 7 V, IO = 150 mA* IQ ENABLE Input Voltage VEH VEL ENABLE Input Current Internal Reference Voltage ADJUST Input Current Rejection Ratio Output Noise Thermal Shutdown IE VREF IADJ PSRR en TJ A8405SLH-ADJ only VI = VO(nom) + 1.5 V, Vi = 100 mV, IO = 30 mA, f = 60 Hz 10 Hz f 100 kHz, IO = 10 mA, CO = 10 F VI 7 V, VE 0.8 V, IO = 0 mA VI VO(nom) + 1 V, Output ON VI VO(nom) + 1 V, Output OFF VE = VI = 7 V VI = 6 V, IO = 10 mA, TJ 125C Min. -- -- -- -- 200 -- -- -- -- -- -- -- -- -- 2.0 -- -- -- -- -- -- -- Typ. 0.5 -- -- TBD -- 1.0 2.0 2.0 100 80 80 80 80 -- -- -- -- 1.26 0.10 70 0.2 170 Max. -- 2.0 -0.25 -- -- 2.0 -- -- -- 100 100 100 100 1.0 -- 0.4 1.0 -- -- -- -- -- Units % % V mV/C mA mV mV mV mV A A A A A V V A V A dB V/Hz C
Typical values are at TA = +25C and are given for circuit design information only. * Pulse test (20 ms). See previous page for duty cycle limitations.
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 F. 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 F. However, to ensure stable operation under all conditions and capacitor types, the recommended minimum value is 4.7 F. The output capacitor may be partially distributed through the load circuits. However, at least 1 F 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 k.
INPUT (7.0 V MAX) 0.1 F (MIN) ENABLE (ACTIVE HIGH)
OUTPUT (2.0 V TO 6.8 V)
5 1
VR
2 4 3
1 F (MIN) R1
R2 (300 k 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 (RJA = 220C/W with a minimum footprint). Performance improvement is easily accomplished with the addition of 1 square inch of copper at terminal 2 (RJA = 170C/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 0.083 0.073 0.022
REF 5 1 2 4 3
0.0079 0.0059 0.118 0.106 0 TO 8 0.037
BSC
0.0098 MIN
0.028
5 4
0.039 0.095
1 2 3
0.037
Dwg. MA-011-5 in
0.0059 0.00
0.043 0.035 0.049 0.035
Dwg. MA-010-15 in
Dimensions in Millimeters
(controlling dimensions)
3.10 2.90 0.45 0.30 2.10 1.85 0.55
REF 5 1 2 4 3
0.20 0.15 3.00 2.70 0 TO 8 0.95
BSC
0.25 MIN
0.70
5 4
1.00 2.40
1 2 3
0.95
Dwg. MA-011-5 mm
0.15 0.00
1.10 0.90 1.25 0.90
Dwg. MA-010-15 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.
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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