AS1901-C31-T - Austriamicrosystems

AS1901, AS1902, AS1903

Ultra Low-Power µP Supervisory Circuit

Data Sheet

www.austriamicrosystems.com Revision 1.51 1 - 9

1 General Description

The AS1901/2/3 family is an ultra low-power supervisory

circuit device.

The device can be used to monitor the supply voltage of

digital systems and microprocessors and initiate a reset

when the voltage goes below a predefined threshold.

The duration of the reset is 5/20/100/500ms (typ.) after

the supply voltage has risen above the thre shold.

The AS1901/2/3 exhibit excelle nt reliability and can

reduce application costs by eliminating all external com-

ponents.

The device is available with different output drivers:

!The AS1901 has a push-pull driver with an active low

reset.

!The AS1902 uses the same output stage as the

AS1901, but has an active high reset.

!The AS1903 has an open drain output with active low

reset.

All devices operate down to a voltage of 1V.

The reset thresholds are factory-trimmable between

2.2V and 3.08V in steps of approximately 100mV.

Each device of the AS1901/2/3 family is offered with four

time-out periods of 5/20/100/500ms.

The extremely low current consumption of only 230nA

(typ) at 3.3V makes the device ideal for use in portable

applications.

All devices are availabl e i n a 3-pin SOT23 package.

Figure 1. Functional Block Diagrams

2 Key Features

!Low 230nA (typ) Supply Current

!Precision Monitoring of 2.5- , 3-, and 3.3V-Power

Supplies

!Supply Voltage Range: 1.0 to 3.6V

!Reset Threshold Range: 2.2 to 3.1V

!Available in 3 Versions:

- AS1901 Push Pull RESETN

- AS1902 Push Pull RESET

- AS1903 Open Drain RESETN

!4 Time-Out Periods Ranging from 5 to 500ms

!Detection Voltage Accuracy: ±1.5%

!Temperature Range: -40 to +85°C

!Package: SOT23-3

3 Applications

The devices are ideal for computers, intelligent instru-

ments, controllers, critical microprocessor and micro-

controller, power monitoring and portable/battery-

powered equipment.

VCC

AS1903 Microprocessor

VDD

GND GND

RESETN RESET I/O

VCC

AS1901

AS1902 Microprocessor

VDD

GND GND

RESETN,

RESET RESET

VCC

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AS1901, AS1902, AS190 3

Data Sheet - P i n o ut

4 Pinout

Pin Assignments

Figure 2. Pin Assignments (Top View)

Pin Descriptions

Table 1. Pin Descriptions

Pin Number Pin Name Description

AS1901/AS1903 AS1902

11GND Ground

2 - RESETN Active-low reset output. RESETN remains low while VDD is

below the reset threshold and for tTP after VDD rises above

the reset threshold. RESETN is open-drain on the AS1903

and push-pull on the AS1901.

- 2 RESET Active-high reset output. RESET remains high while VDD is

below the reset threshold and for tTP after VDD rises above

the reset threshold.

33V

DD Supply voltage.

Top View

AS1901

AS1902

AS1903

SOT23-3

VDD

GND

RESETN,

RESET

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AS1901, AS1902, AS190 3

Data Sheet - A b s o lu t e M a xi m u m R a ti n g s

5 Absolute Maximum Ratings

Stresses beyond those listed in Ta b l e 2 ma y caus e pe rmanent damage to the device. These are stress ratings only,

and functional operation of the device at these or any othe r conditions beyond those indicated in Section 6 Electrical

Characteristics is not implied. Exposure to absolute maximum rating conditions for extended periods may affect device

reliability.

Table 2. Absolute Maximum Ratings (TA = 25°C Unless Otherwise Noted)

Parameter Limits Unit Notes

VDD to GND -0.3 to +5 V

RESET/RESETN to GND -0.3 to VDD + 0.3 V

Input Current (VDD) 20 mA

Output Current (RESET, RESETN) 20 mA

Rate of Rise (VDD) 100 V/µs

Operating Temperature Range (TA) -40 to +85 °C

Storage Temperature Range -65 to +150 °C

Package-Body Peak Temperature +260 °C

The reflow peak soldering temperature (body

temperature) specified is in accordance with

IPC/JEDEC J-STD-020C “Moisture/Refl ow

Sensitivity Classifi cation for non-hermetic

Solid State Surface Mount Devices”

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AS1901, AS1902, AS190 3

Data Sheet - E l e ct r i c a l C h a r a c t er i s t i c s

6 Electrical Characteristics

VDD = Full Range; TA = -40 to +85ºC; Unless Otherwise Specified

Notes:

1 See Table 6, “Coding of Factory-Trimmed Reset Threshold Voltages,” on page 6.

2 Guaranteed by design.

3 See Table 4, “Coding of Factory-trimmed Reset Active Time-Out Period,” on page 6.

Table 3. Electrical Characteristics

Parameter Symbol Conditions Min Typ Max Unit

VDD Range VDD TA = 0 to +70°C 1.0 3.6 V

TA = -40 to +85°C 1.2 3.6

Supply Current (AS1901/2/3) IDD VDD = 3.3V, No Load 230 430 nA

Reset Threshold Voltage1 VTH TA = +25°C VTH -

1.5% VTH VTH +

1.5% V

TA = -40 to +85°C VTH -

2.5% VTH VTH +

2.5%

VDD to Reset Delay2tRD VDD = VTH to (VTH - 100mV) 20 50 µs

Reset Active Time-Out Period3tTP tTP -

40% tTP tTP +

60% ms

RESETN Output Voltage (AS1901/3) VOL

ISINK = 1.2mA, VDD = 2.1V, Reset

Asserted 0.4 V

ISINK = 400µA, VDD = 1.2V, Reset

Asserted 0.4 V

RESETN Output Voltage (AS1901) VOH ISOURCE = 1.2mA, VDD = 3.2V 0.8 x

VDD V

RESET Output Voltage (AS1902) VOH

ISOURCE = 500µA, VDD = 2.1V,

Reset Asserted 0.8 x

VDD V

ISOURCE = 100µA, VDD = 1.2V,

Reset Asserted 0.8 x

VDD V

VOL ISINK = 1.2mA, VDD = 3.2V,

Reset Not Asserted 0.4 V

RESET Threshold Hysteresis VHYST 10 mV

Open-Drain RESETN Output

Leakage Current (AS1903) ILEAK 0.1 µA

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AS1901, AS1902, AS190 3

Data Sheet - Ty p i ca l O p e r at i n g C ha r a c t e r is t i c s

7 Typical Operating Characteristics

Figure 3. Supply Current vs. Temperature Figure 4. Power Down Reset Delay vs. Temp .

Figure 5. Power-Up Reset Timeout vs. Temperature Figure 6. Max. Trans. Duration vs. Reset Th. Overdrive

0.1

0.2

0.3

0.4

0.5

-40 -15 10 35 60 85

Temperature(°C)

Supply Cur r ent (m A ) .

100

125

150

175

200

-40 -15 10 35 60 85

Temperature(°C)

Reset Delay (µ s ) .

VOD = 10mV

100

125

150

175

200

-40 -15 10 35 60 85

Temperature(°C)

Power - Up Reset Timeout (m s ) .

100

125

150

175

200

1 10 100 1000

Reset Th. Overdr ive VTH-VCC (mV)

M ax . T r ans ient Duration ( µs) .

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AS1901, AS1902, AS190 3

Data Sheet - D e ta i l e d D es c r i p t io n

8 Detailed Description

Interfacing to Microprocessors with Bi-Directional Reset Pins

The device has an open drain RESETN output, which enables easy interfacing to microprocessors (µP) with bi-direc-

tional reset pins, such as the Motorola 68HC11. The RESETN pin of the microcontroller (µC) can be connected directly

to the µP supervisor's RESETN output with a single pull-up resistor (see Figure 1 on page 1).

Negative-Going VDD Transients

The device is optimized to ignore short-duration, negative-going VDD transients (glitches) in order to avoid incorrect

resets.

In the graph Maximum T ransient Duration vs. Reset Threshold Overdrive (page 6), the conditions are shown, for which

the reset pulses are not generated. In the graph the maximum pulse width that a negative VDD transient may have

when a reset signal is generated. As the amplitude of the transient increases, the maximum allowable pulse width

decreases.

Options

Table 4. Coding of Factory-tri mmed Reset Active Time-Out Period

Device Suffix tTP in Milliseconds

Min Typ Max

AS190x_xx A 3 5 8

AS190x_xx B 12 20 32

AS190x_xx C 60 100 160

AS190x_xx D 300 500 800

Table 5. Output Variants

Device Output Functionality

AS1901xxx Active Low (RESETN)

AS1902xxx Active High (RESET)

AS1903xxx Open Drain (RESETN)

Table 6. Coding of Factory-Trimmed Reset Threshold Voltages

Device Suffix Reset Thres ho ld Vo ltage, VTH in V

TA = +25°C TA = -40 to +85°C

Min Typ Max Min Max

AS190xx__ 22 2.167 2.2 2.233 2.145 2.255

AS190xx__ 23 2.285 2.32 2.355 2.262 2.378

AS190xx__ 24 2.364 2.4 2.436 2.340 2.460

AS190xx__ 25 2.463 2.5 2.538 2.438 2.563

AS190xx__ 26 2.591 2.63 2.669 2.564 2.696

AS190xx__ 27 2.660 2.7 2.741 2.633 2.768

AS190xx__ 28 2.758 2.8 2.842 2.730 2.870

AS190xx__ 29 2.886 2.93 2.974 2.857 3.003

AS190xx__ 30 2.955 3.0 3.045 2.925 3.075

AS190xx__ 31 3.034 3.08 3.126 3.003 3.157

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AS1901, AS1902, AS190 3

Data Sheet - P a c kage Drawings and Markings

9 Package Drawings and Markings

The device is available in a 3-pin SOT-23 package.

Figure 7. 3-Pin SOT- 23 Package.

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AS1901, AS1902, AS190 3

Data Sheet - O r d er i n g I n fo r m a t i o n

10 Ordering Information

The device is available in the following standard versions.

Non-standard versions require a minimum order of 30,000 units. Contact austriamicrosystems for availability of non-

standard versions.

Standard Part Threshold Duration Marking

AS1901C23 2.32 100ms ASBA

AS1901C26 2.63 100ms ASBD

AS1901C31 3.08 100ms ASBI

AS1902C23 2.32 100ms ASBK

AS1902C26 2.63 100ms ASBN

AS1902C31 3.08 100ms ASBS

AS1903C23 2.32 100ms ASBU

AS1903C26 2.63 100ms ASBX

AS1903C31 3.08 100ms ASB3

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AS1901, AS1902, AS190 3

Data Sheet

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Disclaimer

Devices sold by austriamicrosystems AG are covered by the warranty and patent indemnification provisions appearing

in its Te rm of Sale. austriamicrosystems AG makes no warranty, express, st atutory, implied, or by description regarding

the information set forth herein or rega rd i ng th e fre e do m of the described devices from patent infringement. austriami-

crosystems AG reserves the right to change specifications and prices at any time and withou t notice. Therefore, prior

to designing this product into a system, it is necessary to check with austriamicrosystems AG for current information.

This product is intended for use in normal commercial applications. Applicati ons requiring extended temperature

range, unusual environmental requirements, or high reliability applications, such as military, medical life-support or life-

sustaining equipment are specifically not recommended without additional processing by austriamicrosystems AG for

each application. For shipments of less than 100 parts the manufacturing flow might show deviations from the standard

production flow, such as test flow or test location.

The information furnished here by austriamicrosystems AG is believed to be correct and accurate. However,

austriamicrosystems AG shall not be liable to recipient or any third party for any dama ges, including but not limited to

personal injury, property damage, loss of profits, loss of use, interruption of business or indirect, speci al, incide ntal or

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austriamicrosystems AG rendering of technical or other services.

Cont act Information

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A-8141 Schloss Premstaetten, Austria

Tel: +43 (0) 3136 500 0

Fax: +43 (0) 3136 525 01

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