MIC2755BMM Micrel Inc, MIC2755BMM Datasheet

MIC2755BMM

Manufacturer Part Number

MIC2755BMM

Description

IC SUPERVISOR BATT SYSTEM 8-MSOP

Manufacturer

Micrel Inc

Type

Battery Backup Circuitr

Datasheet

1.MIC2755YMM_TR.pdf (10 pages)

Specifications of MIC2755BMM

Number Of Voltages Monitored

Output

Open Drain or Open Collector

Reset

Active Low

Reset Timeout

700 ms Minimum

Voltage - Threshold

Adjustable/Selectable

Operating Temperature

-40°C ~ 85°C

Mounting Type

Surface Mount

Package / Case

8-MSOP, Micro8™, 8-uMAX, 8-uSOP,

Lead Free Status / RoHS Status

Contains lead / RoHS non-compliant

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General Description

The MIC2755 is composed of multiple comparators, a reset

pulse generator, and logic. It is designed for monitoring the

battery supply of portable digital systems, including PDAs

and pagers.

The MIC2755 detects three different battery states: battery

OK, low battery, and dead battery. The reset (/RST) output is

asserted for at least 700ms when a fresh battery is inserted.

The nonmaskable interrupt output (/NMI) is asserted when

the battery voltage is below the NTH threshold, indicating that

high-power system operations should not occur. If and when

battery voltage falls below the power-off threshold (PTH),

the reset output is asserted and latched, inhibiting system

operation until the battery is replaced or recharged.

All three voltage thresholds are set using external resistors.

A manual reset function can be implemented by connecting

a switch directly to the power on reset/manual reset [RTH(/

MR)] input. Internal circuitry detects switch activation and

generates a minimum 175ms debounced reset signal. The

MIC2755’s power supply input is separate from the detector

inputs to allow it to be powered from a down-stream voltage,

such as the output of a boost converter.

Inputs and outputs can be pulled above V

absolute maximum) without adverse effects or excessive

current draw.

Supply current is typically a low 2µA. Hysteresis is included

on all voltage detectors to prevent chattering due to noise.

The MIC2755 is available in the tiny 8-pin micro-small-outline

package.

Typical Application

January 2006

MIC2755

Micrel, Inc. • 2180 Fortune Drive • San Jose, CA 95131 • USA • tel + 1 (408) 944-0800 • fax + 1 (408) 474-1000 • http://www.micrel.com

BAT(OK)

BAT(low)

BAT(dead)

Supervised Boost Converter and Microcontroller or Microprocessor

= 3.6V

= 3.1V

RESET

= 2.9V

656k

344k

BAT

26.7k

576k

400k

(up to 7V

VDD

PTH

NTH

RTH(/MR)

MIC2755

/POF

/RST

GND

/NMI

100k

Features

• Optimized for PDAs, pagers and

• Detects multiple battery states:

• Adjustable voltage thresholds

• High accuracy ±2% voltage thresholds

• Reset generation at power-on (700ms min.)

• Debounced manual reset function

• Internal logic prevents chatter if battery voltage

• Extremely low 2µA typical supply current

• I/Os can be pulled above V

• Immune to brief power supply transients

• Low cost

• 8-pin MSOP

ﬂuctuates

other hand-held devices.

- battery OK

- low battery

- dead battery

Boost or Buck

Converter

Battery System Supervisor

OUT

100k 100k

MIC2755

SUPPLY

/NMI

/RST

GND

µController or

µProcessor

(7V absolute maximum)

Micrel, Inc.

MIC2755

Related parts for MIC2755BMM

MIC2755BMM Summary of contents

Page 1

MIC2755 General Description The MIC2755 is composed of multiple comparators, a reset pulse generator, and logic designed for monitoring the battery supply of portable digital systems, including PDAs and pagers. The MIC2755 detects three different battery states: battery ...

Page 2

... MIC2755 Pin Conﬁguration Part Number Junction Temp. Range Standard Pb-Free MIC2755BMM MIC2755YMM Pin Conﬁguration Pin Description Pin Number Pin Name 1 RTH(/MR) 2 NTH 3 PTH 4 GND 5 /POF 6 /NMI 7 /RST 8 VDD MIC2755 Package –40ºC to +185ºC 8-Pin MSOP RTH(/MR) ...

Page 3

MIC2755 Absolute Maximum Ratings Supply Voltage (V ) .......................................–0.3V to +7V DD Input Voltage ( RTH NTH PTH Output Voltage ( /RST /NMI /POF /RST Output Current (I ) ........................................ 20mA /RST ...

Page 4

MIC2755 Timing Diagram Block Diagram NTH PTH RTH(/MR) 1.24V Ref1 GND MIC2755 Propagation delays not shown for clarity. The MIC2755 ignores very brief transients. See “Application Information” for details. VDD 20mV Hysteresis 1.24V Ref2 310mV 4 Micrel, Inc. /NMI /RST ...

Page 5

MIC2755 Functional Description Typically the MIC2755 is used to monitor the battery supply of intelligent circuits such as microcontrollers and micropro- cessors. By connecting the reset output of a MIC2755 to the reset input of a µC or µP, the ...

Page 6

MIC2755 Applications Information Outputs Since the MIC2755 outputs are open-drain MOSFETs, most applications will require pull-up resistors. The value of the resistors should not be too large or leakage effects may dominate. Programming Thresholds There are separate resistive-divider conﬁgurations for ...

Page 7

MIC2755 R10 = 400k 1MΩ = R10+R11  2.9V = 1.24V  BAT(dead)  400k R9 = 27k R8 = 1MΩ – R9 – R10 = 573k The accuracy of the resistors can be chosen based ...

Page 8

MIC2755 MIC2755 8 Micrel, Inc. January 2006 ...

Page 9

MIC2755 January 2006 9 Micrel, Inc. MIC2755 ...

Page 10

... TYP MICREL INC. 2180 FORTUNE DRIVE SAN JOSE, CA 95131 USA + 1 (408) 944-0800 TEL This information furnished by Micrel in this data sheet is believed to be accurate and reliable. However no responsibility is assumed by Micrel for its use. Micrel reserves the right to change circuitry and speciﬁcations at any time without notiﬁcation to the customer. ...

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