DS2740 High-Precision Coulomb Counter www.maxim-ic.com PIN CONFIGURATION FEATURES 15-Bit Bidirectional Current Measurement (DS2740U) 1 8 V OVD DD 1.56V LSB and 51.2mV Dynamic 2 7 DQ PIO Range SNS 3 6 V SS 78A LSB and 2.56A Dynamic 4 5 IS2 IS1 Range with External 20m Sense MAX Resistor (R ) SNS (DS2740U, DS2740BU) 156A LSB and 5.12A Dynamic Range with External 10m Sense Resistor (R ) See Table 1 for Ordering Information. SNS 13-Bit Bidirectional Current Measurement See Table 2 for Detailed Pin Descriptions. (DS2740BU) 6.25V LSB and 51.2mV Dynamic PIN DESCRIPTION Range OVD - 1-Wire Bus Speed Select 312A LSB and 2.56A Dynamic PIO - Programmable I/O Pin Range with External 20m Sense SNS - Sense Resistor Input Resistor (R ) SNS IS2 - Current-Sense Input 625A LSB and 5.12A Dynamic IS1 - Current-Sense Input Range with External 10m Sense V - Device Ground, Current-Sense Resistor SS Resistor (R ) SNS Return Analog Input Filter (IS1, IS2) Extends DQ - Data Input/Output Dynamic Range for Pulse-Load V - Power-Supply Input (2.7V to 5.5V) DD Applications Current Accumulation Register Resolution 6.25Vhr (Both DS2740U and DS2740BU) 0.3125mAhr with External 20m R SNS 0.6250mAhr with External 10m R SNS Dallas 1-Wire Interface Unique 64-Bit Device Address Standard and Overdrive Timings (OVD) Low Power Consumption: Active Current: 65A max Sleep Current: 1A max 1-Wire is a registered trademark of Dallas Semiconductor. 1 of 16 051805 DS2740 Table 1. ORDERING INFORMATION PART MARKING DESCRIPTION DS2740U D2740 15-Bit Current Resolution, 8-Pin MAX DS2740U+ D2740 (see note) 15-Bit Current Resolution, Lead-Free 8-Pin MAX DS2740U/T&R D2740 15-Bit Current Resolution, 8-Pin MAX, Tape-and-Reel 15-Bit Current Resolution, Lead-Free 8-Pin MAX, Tape- DS2740U+T&R D2740 (see note) and-Reel DS2740BU 2740B 13-Bit Current Resolution, 8-Pin MAX DS2740BU+ 2740B (see note) 13-Bit Current Resolution, Lead-Free 8-Pin MAX DS2740BU/T&R 2740B 13-Bit Current Resolution, 8-Pin MAX, Tape-and-Reel 13-Bit Current Resolution, Lead-Free 8-Pin MAX, Tape- DS2740BU+T&R 2740B (see note) and-Reel Note: A + will also be marked on the package next to the pin 1 indicator. 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. FuelPack is a trademark of Dallas Semiconductor. 2 of 16