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DS2740

High-Precision Coulomb Counter

High-Precision Battery Fuel Gauge Costs Less than $1.00 Ideal for Handheld Products

Overview

Technical Documents

Ordering Info

Status

Part Number	Status
DS2740	Active: In Production. See Ordering Information for details.

Description

The DS2740 provides high-precision current-flow measurement data to support battery-capacity monitoring in cost-sensitive applications. Current is measured bidirectionally over a dynamic range of 15 bits (DS2740U) or 13 bits (DS2740BU), with the net flow accumulated in a separate 16-bit register. Through its 1-Wire® interface, the DS2740 allows the host system read/write access to status and current measurement registers. Each device has a unique factory-programmed 64-bit net address that allows it to be individually addressed by the host system, supporting multibattery slot operation. The interface can be operated with standard or overdrive timing.

Although the DS2740 is primarily intended for location on the host system, it is also suited for mounting in the battery pack. The DS2740 and FuelPack™ algorithms, along with host measurements of temperature and voltage, form a complete and accurate solution for estimating remaining capacity.

Data Sheet

Download	Rev 4	(PDF, 312kB)
E-Mail

An evaluation kit is available: DS2740EVKIT

NOTE: This product uses the following:
DS2740K Evaluation Kit Software

Key Features

15-Bit Bidirectional Current Measurement (DS2740U)
- 1.56µV LSB and ±51.2mV Dynamic Range
- 78µA LSB and ±2.56A Dynamic Range with External 20mΩ Sense Resistor (R_SNS)
- 156µA LSB and ±5.12A Dynamic Range with External 10mΩ Sense Resistor (R_SNS)
13-Bit Bidirectional Current Measurement (DS2740BU)
- 6.25µV LSB and ±51.2mV Dynamic Range
- 312µA LSB and ±2.56A Dynamic Range with External 20mΩ Sense Resistor (R_SNS)
- 625µA LSB and ±5.12A Dynamic Range with External 10mΩ Sense Resistor (R_SNS)
Analog Input Filter (IS1, IS2) Extends Dynamic Range for Pulse-Load Applications
Current Accumulation Register Resolution
- 6.25µVhr (Both DS2740U and DS2740BU)
- 0.3125mAhr with External 20mΩ R_SNS
- 0.6250mAhr with External 10mΩ R_SNS
Dallas 1-Wire Interface
- Unique 64-Bit Device Address
- Standard and Overdrive Timings (OVD)
Low Power Consumption:
- Active Current: 65µA max
- Sleep Current: 1µA max

Applications/Uses

Cell Phones
Digital Still Cameras
Portable Entertainment Devices
Smart Battery Packs/Chargers

Key Specifications:

Battery Protectors, Selectors and Monitors

Part Number

Functions

Battery Type

Interface

Parameters Measured

V_SUPPLY
(V)

Package/Pins

Smallest Available Pckg.
(mm²)

Oper. Temp.
(°C)

Budgetary Price

min

max

max w/pins

See Notes

DS2740

Fuel Gauge

1 Cell Li-Ion

3-Cell NiMH

1-Wire

Current

2.7

5.5

µMAX/8

16.2

-40 to +85

$1.31 @1k

See All Battery Protectors, Selectors and Monitors (29)

Pricing Notes:
This pricing is BUDGETARY, for comparing similar parts. Prices are in U.S. dollars and subject to change. Quantity pricing may vary substantially and international prices may differ due to local duties, taxes, fees, and exchange rates. For volume-specific prices and delivery, please see the price and availability page or contact an authorized distributor.

Diagram

Pin Configurations

Application Notes

Tutorial 148		Guidelines for Reliable Long Line 1-Wire® Networks
Application Note 187		1-Wire Search Algorithm
Tutorial 214		Using a UART to Implement a 1-Wire Bus Master
Application Note 1919		Increasing the Fuel Gauge Dynamic Range
Application Note 2096		DS2740 High-Precision Coulomb Counter Reference Design
Application Note 2420		1-Wire® Communication with a Microchip PICmicro Microcontroller
Application Note 3092		Alternate DS2740U Application Circuit with Reduced Current Measurement Offset Error

Reliability Reports

Reliability Report:

DS2740.pdf

Software/Models

DS2740K Evaluation Kit Software

Ordering Information

Filters:

Part Number:

Package:

Temperature:

Tape and Reel

Sample

Part Number	Free Sample	Buy	Status	Recommended Replacement	Package: TYPE PINS FOOTPRINT DRAWING CODE/VAR *	Temp	RoHS/Lead-Free? Materials Analysis
DS2740BU+			Active		µMAX;8 pin;16.2 mm² Outline Drawing:21-0036 (PDF) Land Pattern: 90-0092 (PDF) Use pkgcode/variation: U8+3*	-40°C to +85°C	RoHS/Lead-Free: Lead Free Materials Analysis
DS2740BU+T&R			Active		µMAX;8 pin;16.2 mm² Outline Drawing:21-0036 (PDF) Land Pattern: 90-0092 (PDF) Use pkgcode/variation: U8+3*	-40°C to +85°C	RoHS/Lead-Free: Lead Free Materials Analysis
DS2740BU/T&R		N/A	No Longer Available	DS2740BU+T&R	USOP; Land Pattern: Not Available	-40°C to +85°C	See data sheet
DS2740U+			Active		µMAX;8 pin;16.2 mm² Outline Drawing:21-0036 (PDF) Land Pattern: 90-0092 (PDF) Use pkgcode/variation: U8+3*	-40°C to +85°C	RoHS/Lead-Free: Lead Free Materials Analysis
DS2740U+T&R			Active		µMAX;8 pin;16.2 mm² Outline Drawing:21-0036 (PDF) Land Pattern: 90-0092 (PDF) Use pkgcode/variation: U8+3*	-40°C to +85°C	RoHS/Lead-Free: Lead Free Materials Analysis
DS2740U/T&R		N/A	No Longer Available	DS2740U+T&R	USOP; Land Pattern: Not Available	-40°C to +85°C	See data sheet

Notes:

Other options and links for purchasing parts are listed at: http://www.maxim-ic.com/sales.
Didn't Find What You Need? Ask our applications engineers. Expert assistance in finding parts, usually within one business day.
Part number suffixes: T or T&R = tape and reel; + = RoHS/lead-free; # = RoHS/lead-exempt; -D = drypack; -U/+U on DS parts = cut tape. More: See Full Data Sheet or Maxim Product Naming Conventions.
* Some packages have variations, listed on the drawing. "PkgCode/Variation" tells which variation the product uses. Note that "+", "#", "-" in the part number suffix describes RoHS status. Package drawings may show a different suffix character.

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