ADMOS AMS2942BS, AMS2942AS Datasheet

Advanced AMS2942

PACKAGE TYPE

OPERATING

8 LEAD SOIC

TEMP. RANGE

AMS2942AS

IND

AMS2942BS

IND

Monolithic HIGH VOLTAGE LOW DROPOUT REGULATOR
Systems

FEATURES APPLICATIONS

•• Adjustable from 1.23V to 42V •• Telephone Systems

•• High Accuracy Output Voltage •• High Voltage Power Supply

•• Extremely Low Quiescent Current •• Cordless Telephones

•• Low Dropout Voltage •• Laboratory Instrumentation

•• Tight Load and Line Regulation •• Radio Control Systems

•• Low Temperature Coefficient •• Automotive Electronics

•• Current and Thermal Protection •• Avionics

•• Unregulated DC Positive Transients 60V

•• Error Flag Warning of Voltage Output Dropout

•• Logic Controlled Electronic Shutdown

GENERAL DESCRIPTION

The AMS2942 are micropower voltage regulators ideally suited for use with high voltage powered systems. This device
feature very low quiescent current (typ.130µA), and very low dropout voltage (typ.45mV at light loads and 380mV at
100mA). The quiescent current increases only slightly in dropout. The AMS2942 has positive transient protection up to 60V
and can survive unregulated input transient up to 20V below ground.
AMS2942 is designed with a tight initial voltage reference tolerance, excellent load and line regulation (typ. 0.05%), and a
very low output voltage temperature coefficient, making these devices useful as a low-power voltage regulator in telephone
applications, using the telephone line as a power source.
The AMS2942 is available in a special 8-pin plastic SOIC in which pin 2 and 3 are fused together with the package paddle
serving also as heat sink. An error flag output warns of a low output voltage, often due to failing voltage on input line. A
logic-compatible shutdown input is available, which enables the regulator to be switched on and off. The output voltage can
be programmed from 1.23V to 42V with an external pair of resistors.

ORDERING INFORMATION PIN CONNECTION

Advanced Monolithic Systems, Inc. 6680B Sierra Lane, Dublin, CA 94568 Phone [phone] Fax [phone]

8L SOIC

1

OUTPUT INPUT

2

GROUND

3

GROUND

4

ON/OFF

8
7

FEEDBACK
6 N/C
5

ERROR

Top View

AMS2942

ABSOLUTE MAXIMUM RATINGS (Note 1)

Input Supply Voltage -0.3 to +50V ESD 2000V
Power Dissipation Internally Limited
Junction Temperature

Storage Temperature

-65°C to +150°C

Soldering Dwell Time, Temperature Junction Temperature Range
Wave
Infrared
Vapor Phase

4 seconds, 260°C
4 seconds, 240°C

4 seconds, 219°C

+150°C

OPERATING RATINGS (Note 1)

Max. Input Supply Voltage 45V

-40°C to +125°C

(TJ) (Note 8)

ELECTRICAL CHARACTERISTICS at V

Parameter Conditions

Reference Voltage 1.22 1.235 1.25 1.21 1.235 1.26 V
Reference Voltage Over Temperature (Note 7)

Output Voltage
Temperature Coefficient (Note 10) (Note 4)

Line Regulation (Note 12)
Load Regulation (Note 12)
Dropout Voltage

(Note 5)

Ground Current

Current Limit V
Thermal Regulation (Note 11) 0.05 0.2 0.05 0.2 %/W
Output Noise,

10Hz to 100KHz

Feedback Pin Bias Current 40 80 40 80 nA
Reference Voltage Temperature

Coefficient
Feedback Pin Bias Current
Temperature Coefficient

Error Comparator

Output Leakage Current V
Output Low Voltage
Upper Threshold Voltage (Note 6) 40 60 40 60 mV

Lower Threshold Voltage (Note 6) 75 95 75 95 mV
Hysteresis (Note 6) 15 15 mV

Shutdown Input

Input logic Voltage

Shutdown Pin Input Current
(Note 3)

Regulator Output Current in
Shutdown (Note 3)

6V ≤ V
100 µA ≤I

IL = 100µ A
I

= 100 mA

L

I

= 100 µA

L

I

= 100 mA

L

OUT

C

= 1µF

L

CL = 200 µF
C

= 13.3 µF

L

(Bypass = 0.01 µF pins 7 to 1)

( Note 10) 20 50 ppm/°C

OH

V

IN

Low (Regulator ON)
High (Regulator OFF)
VS = 2.5V

VS = 42V
(Note 9) 15 50 15 50

(Note 2)

≤ 45V (Note 13)

IN

≤ 100 mA

L

= 0 160 200 160 200 mA

= 42V 0.05 2 0.05 2

= 4.5V, IOL = 400µA

=V

+1V, TA=25°C, unless otherwise specified.

OUT

S

AMS2942A

Min. Typ. Max.

1.19 1.27 1.185 1.285
20 50

0.05 0.2 0.1 0.4 %

0.05 0.2 0.1 0.4 %
50

380
120

8

430
160
100

0.1 0.1 nA/°C

150 250 150 250 mV

2.5

1.3

30

600

80

450
180

12

0.7

60

850

AMS2942B

Min. Typ. Max.

50

380
120

8

430
160
100

1.3

2.5

30

600

80

450
180

12

0.7

60

850

Units

V

ppm/°C

mV
mV

µA

mA

µV rms
µV rms
µV rms

µA

V
V

µA
µA

µA

Advanced Monolithic Systems, Inc. 6680B Sierra Lane, Dublin, CA 94568 Phone [phone] Fax [phone]

BLOCK DIAGRAM AND TYPICAL APPLICATIONS

AMS2942

AMS2942

39V to 45V UNREGULATED DC

+

FROM
CMOS

OR TTL

SHUT-

DOWN

ERROR DETECTION COMPARATOR

50mV

+

+

1.23V
REFERENCE

INPUT OUTPUT

+

ERROR

­AMPLIFIER

+

-

FEED­BACK

ERROR

GROUND

+

10µF

298kΩ

10kΩ

330kΩ

VO = 38V

TO CMOS
OR TTL

Note 1: Absolute Maximum Ratings are limits beyond which damage to the device may occur. Operating Ratings are conditions under which operation of the
device is guaranteed. Operating Ratings do not imply guaranteed performance limits. For guaranteed performance limits and associated test conditions, see the
Electrical Characteristics tables.
Note 2: Unless otherwise specified all limits guaranteed for V
entire junction temperature range for operation. Limits appearing in normal type apply for TA = TJ = 25°C, V

IN

= ( V

+1)V, IL = 100 µA and CL = 1 µF. Limits appearing in boldface type apply over the

ONOM

SHUTDOWN

≤ 0.8V.

Note 3: Guaranteed and 100% production tested.
Note 4: Guaranteed but not 100% production tested. These limits are not used to calculate outgoing AQL levels.
Note 5: Dropout voltage is defined as the input to output differential at which the output voltage drops 100 mV below its nominal value measured at 1V differential.

At very low values of programmed output voltage, the minimum input supply voltage of 2V ( 2.3V over temperature) must be taken into account.
Note 6: Comparator thresholds are expressed in terms of a voltage differential at the feedback terminal below the nominal reference voltage measured at
V

IN

= ( V

+1)V. To express these thresholds in terms of output voltage change, multiply by the error amplifier gain = Vout/Vref = (R1 + R2)/R2. For example,

ONOM

at a programmed output voltage of 5V, the error output is guaranteed to go low when the output drops by 95 mV x 5V/1.235 = 384 mV. Thresholds remain constant
as a percent of V
Note 7: V

as V

is varied, with the dropout warning occurring at typically 5% below nominal, 7.5% guaranteed.

out

out

≤ (Vin - 1V), 2.3 ≤Vin≤42V, 100µA≤IL≤ 100 mA, TJ ≤ T

ref ≤Vout

JMAX

.

Note 8: The junction-to-ambient thermal resistance is 120°C/W for the molded plastic SO-8 (S), when the package is soldered directly to the PCB.
Note 9: V

≥ 2.5V, VIN ≤ 42V, V

SHUTDOWN

OUT

=0.

Note 10: Output or reference voltage temperature coefficients defined as the worst case voltage change divided by the total temperature range.
Note 11: Thermal regulation is defined as the change in output voltage at a time T after a change in power dissipation is applied, excluding load or line regulation

effects. Specifications are for a 50mA load pulse at VIN =42V (1.25W pulse) for T =10 ms.
Note 12: Regulation is measured at constant junction temperature, using pulse testing with a low duty cycle. Changes in output voltage due to heating effects are
covered under the specification for thermal regulation.
Note 13: Line regulation is tested at 150°C for IL = 1 mA. For IL = 100 µA and TJ = 125°C, line regulation is guaranteed by design to 0.2%. See typical
performance characteristics for line regulation versus temperature and load current.

Advanced Monolithic Systems, Inc. 6680B Sierra Lane, Dublin, CA 94568 Phone [phone] Fax [phone]