Datasheet MIC2775-XXBM5 Datasheet (MICREL)

MIC2775 Micrel

RST

/RST

VDD

/MR

GND

MIC2775-17

VDD

OTHER
LOGIC

/RESET

GND

MICROPROCESSOR

Manual
Reset

1.8V

MIC2775

Micro-Power Voltage Supervisor

Advance Information

General Description

The MIC2775 is a power supply supervisor that provides
under-voltage monitoring, manual reset capability, and power­on reset generation in a compact 5-pin SOT package. Fea­tures include an under-voltage detector, a delay generator, a
manual reset input, and both active-high and active-low reset
outputs. The under-voltage detector compares VDD against
a fixed threshold. Ten factory-programmed thresholds are
available.

The reset outputs are asserted for no less than 140ms at
power-on and any time the input voltage drops below the
reference voltage. It remains asserted for the timeout period
after the input voltage subsequently rises back above the
threshold boundary. A reset can be generated at any time by
asserting the manual reset input, /MR. This reset output will
remain active at least 140ms after the release of /MR. The
/MR input can also be used to daisy-chain the MIC2775 onto
existing power monitoring circuitry or other supervisors.
Hysteresis is included to prevent chattering due to noise.
Typical supply current is a low 3.5µA.

Features

• Monitors power supply for under-voltage conditions

• Choice of factory-programmed thresholds

• Generates 140ms (minimum) power-on RESET pulse

• Manual reset capability

• Both active-high and active-low RESET outputs

• /RST output valid down to 1.2V

• Ultra-low supply current, 3.5µA typical

• Rejects brief input transients

• No external components

• Pin compatible upgrade for MAX825

• IttyBitty™ 5-lead SOT-23 package

Applications

• Monitoring processor core and input/output voltages

• Computer systems

• PDAs, hand-held PCs

• Embedded controllers

• Telecommunications systems

• Power supplies

Ordering Information

Part Number Marking Junction Temp. Range Package

MIC2775-XXBM5 UJXX –40°C to +85°C SOT-23-5

Typical Application

IttyBitty™ is a trademark of Micrel, Inc.

September 29, 2000 1 MIC2775

Micrel, Inc. • 1849 Fortune Drive • San Jose, CA 95131 • USA • tel + 1 [phone] • fax + 1 [phone] • http://www.micrel.com

MIC2775 Micrel

Standard Voltage Options*

Voltage Typical Nominal Threshold

Code Application (VDD) Voltage (VTH)

46 5.0V ±5% 4.68

44 5.0V ±10% 4.43

31 3.3V ±5% 3.09

29 3.3V ±10% 2.93

28 3.0V ±5% 2.81

26 2.85V ±5% 2.67

25 2.70V ±5% 2.53

23 2.5V ±5% 2.34

22 2.4V ±5% 2.25

17 1.8V ±5% 1.69

*There are ten standard versions available with an order increment of 3000 pieces. Samples of standard versions are
normally available from stock. Contact factory for information on non-standard versions. Available in tape-and-reel only.

Pin Configuration

Pin Description

Pin Number Pin Name Pin Function

1 RST Digital (Output): Asserted high whenever V

2 GND Ground

3 /RST Digital (Output): Asserted low whenever V

4 /MR Digital (Input): Driving this pin low initiates an immediate and unconditional

5 VDD Analog (Input): Power supply input and the voltage being monitored.

GND

2

/RST

13

VDD/MR

RST

45

SOT-23-5 (M5)

falls below the reference

voltage. It will remain asserted for no less than 140ms after V

DD

above the threshold limit.

falls below the reference

DD

voltage. It will remain asserted for no less than 140ms after V
above the threshold limit.

reset. Assuming V
high), the reset output will be de-asserted no less than 140ms later. /MR

is above the threshold when /MR is released (returns

DD

may be driven by a logic signal or a mechanical switch. /MR has an internal
pull-up to VDD and may be left open if unused.

returns

DD

returns

DD

MIC2775 2 September 29, 2000

MIC2775 Micrel

Absolute Maximum Ratings (Note 1)

Supply Voltage (V
Input Voltage (V

RST, (/RST) Current .................................................. 20mA

Storage Temperature (T

) ..................................... –0.3V to +7V

DD

) ....................................... –0.3V to +7V

/MR

) ....................... –65°C to +150°C

S

Operating Ratings (Note 2)

Supply Voltage (V
Input Voltage (V
Ambient Temperature Range (T

Package Thermal Resistance (θJA) ...................... 256°C/W

) .................................. +1.5V to +5.5V

DD

) .................................... –0.3V to +6.0V

/MR

) ............. –40°C to +85°C

A

ESD Rating, Note 3 ................................................... 1.5kV

Electrical Characteristics

Note 5; TA = +25°C, bold values indicate –40°C ≤ TA ≤ +85°C; unless noted

Symbol Parameter Condition Min Typ Max Units

I

DD

Supply Current VDD = V

open, Note 5

VDD VOLTAGE THRESHOLD

V

HYST

Under-Voltage Threshold On V

Hysteresis Voltage 1%

DD

RST, /RST OUTPUTS

t

PROP

Propagation Delay VDD = VTH + 1.5% + 100mV to 20 µs

VDD = VTH – 1.5% - 100 mV

t

RST

V

OL

Reset Pulse Width 140 280 ms

RST or /RST Output Voltage Low I

SINK

VDD ≥ 1.6V

I

SINK

VDD ≥ 1.2V; Note 4

V

OH

RST or /RST Output Voltage High I

SOURCE

VDD ≥ 1.5V

I

SOURCE

VDD ≥ 1.2V; Note 4

/MR INPUT

V

IH

V

IL

t

PROP

t

MIN

I

PU

I

IN

Note 1. Exceeding the absolute maximum rating may damage the device.

Note 2. The device is not guaranteed to function outside its operating rating.

Note 3. Devices are ESD sensitive. Handling precautions recommended. Human body model, 1.5k in series with 100pF.

Note 4. VDD operating range is 1.5V to 5.5V. Output is guaranteed to be asserted down to VDD = 1.2V.

Note 5. VDD equals nominal “ Typical Application (VDD)” as shown in “Standard Voltage Options Table.”

Input High Voltage 0.7V

Input Low Voltage 0.3V

Propagation Delay From V

Minimum Input Pulse Width Reset Occurs, V

Internal Pull-up Current 100 nA

Input Current, /MR V

/MR

+1.6%, /MR, RST, /RST 3.5 µA

TH

VTH–1.5%

V

THVTH

+1.5%

= 1.6mA; 0.3 V

= 100µA; 0.3 V

= 500µA; 0.8V

= 10µA; 0.8V

< (VIL –100mV) 5 µs

/MR

< V

/MR

IL

< V

IL

DD

DD

DD

DD

33 ns

100 nA

V
V

V

V

V

V

September 29, 2000 3 MIC2775

MIC2775 Micrel

Timing Diagram

V

/MR

V

/RST

(ACTIVE LOW)

V

(ACTIVE HIGH)

RST

V

DD

0V

V

IH

V

IL

V

OH

V

OL

V

OH

V

OL

t

A

RST

A

> t

MIN

t

RST

t

RST

V

V

HYST

TH

Propagation delays not shown for clarity.

Note A. The MIC2775 ignores very brief transients.

See “Applications Information” for details.

MIC2775 4 September 29, 2000

MIC2775 Micrel

Functional Diagram

V

DD

V

REF

V

DD

I

PU

/MR

GND

Functional Description

VDD Input

The VDD pin is both the power supply terminal and a moni­tored input voltage. The voltage at this pin is continually
compared against the internal reference. The trip-point at
which a reset occurs is factory programmed. A reset is
triggered if and when VDD falls below the trip-point. Hyster­esis is employed to prevent chattering due to noise. The
comparator on the VDD input is relatively immune to very brief
negative-going transients.

RST, /RST Reset Outputs

Typically, the MIC2775 is used to monitor the power supply
of intelligent circuits such as microcontrollers and micropro­cessors. By connecting the appropriate reset output of a
MIC2775 to the reset input of a µC or µP, the processor will
be properly reset at power-on and during power-down and
brown-out conditions. In addition, asserting /MR, the manual
reset input, will activate the reset function.

Delay

Line

RSQ

One Shot

/Q

MIC2775

/RST

RST

The reset outputs are asserted any time /MR is asserted or if
VDD drops below the threshold voltage. The reset outputs
remain asserted for t

(min) after VDD subsequently returns

RST

above the threshold boundary and/or /MR is released. A reset
pulse is also generated at power-on. Hysteresis is included in
the comparator to prevent chattering of the outputs due to
noise.

/MR, Manual Reset Input

The ability to initiate a reset via external logic or a manual
switch is provided in addition to the MIC2775’s automatic
supervisory functions. Driving the /MR input to a logic low
causes an immediate and unconditional reset to occur.
Assuming VDD is within tolerance when /MR is released
(returns high), the reset outputs will be de-asserted no less
than t

later. /MR may be driven by a logic signal or

RST

mechanical switch. Typically, a momentary push-button switch
is connected such that /MR is shorted to ground when the
switch contacts close. The switch may be connected directly
between /MR and GND. /MR has an internal 100nA pull-up
current to VDD and may be left open if unused.

September 29, 2000 5 MIC2775

MIC2775 Micrel

Application Information

Ensuring Proper Operation at Low Supply

At levels of VDD below 1.2V, the MIC2775’s /RST output
cannot turn on sufficiently to produce a valid logic-low on
/RST. In this situation, circuits driven by /RST could be
allowed to float, causing undesired operation. (In most cases,
however, it is expected that the circuits driven by the MIC2775
will be similarly inoperative at VDD ≤ 1.2V.)

If a given application requires that /RST be valid below V
= 1.2V, this can be accomplished by adding a pull-down
resistor to the /RST output. A value of 100kΩ is recom­mended as this is usually an acceptable compromise of
quiescent current and pull-down current. The resistor’s value
is not critical, however. See Figure 1.

V

CC

MIC2775-XX

/RST

VDD

RST

GND

/MR

Manual
Reset

MICROPROCESSOR

VCC

100k

/RESET

GND

DD

Transient response

The MIC2775 is inherently immune to very short negative­going “glitches.” Very brief transients may exceed the voltage
threshold without tripping the output.

As shown in Figure 3, in general the narrower the transient,
the deeper the threshold overdrive that will be ignored by the
MIC2775. The graph represents the typical allowable tran­sient duration for a given amount of threshold overdrive that
will not generate a reset.

Typical V

Transient Response

100

80

60

40

20

0

MAX. TRANSIENT DURATION (µs)

0 500 1000 1500 2000

RESET COMP. OVERDRIVE, V

DD

REF–VDD

(mV)

Figure 3. Typical VDD Transient Response

Figure 1. MIC2775 Valid /Reset Below 1.2V

The statements above also apply to the MIC2775’s RST
output. That is, to ensure valid RST signal levels at VDD <

1.2V, a pull-up resistor (as opposed to a pull-down) should be
added to the RST output. A value of 100kΩ is typical for this
application as well. See Figure 2.

V

CC

MIC2775-XX

/RST

VDD

RST

/MR GND

Manual
Reset

MICROPROCESSOR

VCC

/RESET

100k
Rpull-down

GND

Figure 2. MIC2775 Valid Reset Below 1.2V

MIC2775 6 September 29, 2000

MIC2775 Micrel

Package Information

1.90 (0.075) REF

0.95 (0.037) REF

3.02 (0.119)

2.80 (0.110)

0.50 (0.020)

0.35 (0.014)

1.75 (0.069)

1.50 (0.059)

1.30 (0.051)

0.90 (0.035)

0.15 (0.006)

0.00 (0.000)

SOT-23-5 (M5)

3.00 (0.118)

2.60 (0.102)

10°

0°

DIMENSIONS:

MM (INCH)

0.20 (0.008)

0.09 (0.004)

0.60 (0.024)

0.10 (0.004)

MICREL INC. 1849 FORTUNE DRIVE SAN JOSE, CA 95131 USA

TEL + 1 [phone] FAX + 1 [phone] WEB http://www.micrel.com

This information is believed to be accurate and reliable, however no responsibility is assumed by Micrel for its use nor for any infringement of patents or

other rights of third parties resulting from its use. No license is granted by implication or otherwise under any patent or patent right of Micrel Inc.

© 2000 Micrel Incorporated

September 29, 2000 7 MIC2775