MEMORY存储芯片DS3231SN#T&R中文规格书 - 图文

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DS2784

General Description

The DS2784 operates from 2.5V to 4.6V for integration in battery packs using a single lithium-ion (Li+) or Li+ poly-mer cell. Available capacity is reported in mAh and as a percentage. Safe operation is ensured with the included Li+ protection function and SHA-1-based challenge-response authentication.

Precision measurements of voltage, temperature, and current, along with cell characteristics and application parameters are used to estimate capacity. The available capacity registers report a conservative estimate of the amount of charge that can be removed given the current temperature and discharge rate.

In addition to the nonvolatile (NV) storage for cell compen-sation and application parameters, 16 bytes of EEPROM memory is made available for the exclusive use of the host system and/or pack manufacturer. This facilitates battery lot and date tracking or NV storage of system or battery usage statistics.

A 1-Wire? interface provides serial communication at 16kbps or 143kbps to access data registers, control registers, and user memory. Additionally, 1-Wire com-munication enables challenge-response pack authentica-tion using SHA-1 as the hash algorithm in a hash-based message authentication code (HMAC) authentication protocol.

Applications

●Health and Fitness Monitors

●Digital Still, Video, and Action Cameras●Medical Devices

●Handheld Computers and Terminals●Handheld Radios

●Home and Building Automation, Sensors●Smart Batteries●

Power Tools

Ordering Information appears at end of data sheet.

Modes and commands are capitalized for clarity.

1-Wire is a registered trademark of Maxim Integrated Products,Inc.

1-Cell Fuel Gauge with FuelPack,Protector, and SHA-1 Authentication

Features

●Precision Voltage, Temperature, and Current

Measurement System●Available Capacity Estimated from Coulomb

Count, Discharge Rate, Temperature, and CellCharacteristics●Estimates Cell Aging Using Learn Cycles●Uses Low-Cost Sense Resistor

●Allows for Calibration of Gain and Temperature

Coefficient●Li+ Safety Circuitry—Overvoltage, Undervoltage,

Overcurrent, Short-Circuit Protection●Programmable Safety Thresholds for Overvoltage

and Overcurrent●Authentication Using SHA-1 Algorithm and 64-Bit

Secret●32-Byte Parameter EEPROM●16-Byte User EEPROM

●Maxim 1-Wire Interface with 64-Bit Unique ID●Tiny, Pb-Free, 14-Pin TDFN Package Embeds Easily

in Battery Packs Using Thin Prismatic Cells

Simple Fuel Gauge Circuit DiagramPK+1K1K1K1501KPLSDCCCVDDDATA150DQDS2784VINCPPIOCTGSNSVSS5.1VRSNS0.1μF0.1μFPK-DS2784

1-Cell Fuel Gauge with FuelPack,Protector, and SHA-1 Authentication

with a 9V charge pump that increase gate drive as the cell voltage decreases. The high-side topology preserves the ground path for serial communication while eliminating the parasitic charge path formed when the fuel gauge IC is located inside the protection FETs in a low-side con-figuration. The thresholds for overvoltage, overcurrent, and short-circuit current are user programmable for easy customization to each cell and application.

The 32-bit wide SHA-1 engine with 64-bit secret and 64-bit challenge words resists brute force and other attacks with financial-level HMAC security. The challenge of managing secrets in the supply chain is addressed with the compute next secret feature. The unique serial number or ROM ID can be used to assign a unique secret to each battery.

Detailed Description

The The DS2784 functions as an accurate fuel gauge, Li+ protector, and SHA-1-based authentication token. The fuel gauge provides accurate estimates of remain-ing capacity and reports timely voltage, temperature, and current measurement data. Capacity estimates are calculated from a piecewise-linear model of the battery performance over load and temperature, and system parameters for full and empty conditions. The algorithm parameters are user programmable and can be modified in pack. Critical capacity and aging data are periodically saved to EEPROM in case of loss of power due to a short circuit or deep depletion.

The Li+ protection function ensures safe, high-perfor-mance operation. nFET protection switches are driven

Block Diagram

DS2784VOLTAGE(VIN -VSSA)POWER MODECONTROLTEMPERATURELITHIUM ION PROTECTORPLSCURRENT(VSS -SNS)15-BIT + SIGNADCSNSUV, CD10-BIT + SIGNADC/MUXVINFuelPack? FUELPACK?AlgorithmALGORITHMCCFET DRIVERSDCCPVDDCHARGEPUMPCONTROL ANDSTATUS REGISTERSPRECISIONANALOGOSCILLATORWKP, WKDVREFVSSPIO LOGIC32 BYTEPARAMETEREEPROM1-WIRE INTERFACE16 BYTE USEREEPROMPIN DRIVERSAND PWRSWITCHCONTROLPIOVDD_INTDQDS2784

1-Cell Fuel Gauge with FuelPack,Protector, and SHA-1 Authentication

FETs and sets the UV flag in the protection register. If UVEN is set, the DS2784 also enters Sleep mode. The DS2784 provides a current-limited recovery charge path (IRC) from PLS to VDD to gently charge severely depleted cells. The recovery charge path is enabled when 0 ≤ VIN < (VOV - 100mV). Once VIN reaches 2.45V (typ), the DS2784 returns to normal operation. The DS2784 transitions from Sleep to Active mode and the CC and DC outputs are driven high to turn on the charge and discharge FETs. If the device does not enter sleep mode for an UV condition (UVEN=0) then the FETs will turn on once VIN > VUV.Overcurrent, Charge Direction (COC). Charge current develops a negative voltage on VSNS with respect to VSS. If VSNS is less than the charge overcurrent threshold (VCOC) for a period longer than overcurrent delay (tOCD), the DS2784 shuts off both external FETs and sets the COC flag in the protection register. The charge current path is not re-established until the voltage on the PLS pin drops below VDD - VTP. The DS2784 provides a pulldown current (ITST) from PLS to VSS to pull PLS down in order to detect the removal of the offending charge current source.

Li+ Protection Circuitry

During Active mode, the DS2784 constantly monitors SNS, VIN, and VPLS to protect the battery from overvolt-age (overcharge), undervoltage (overdischarge), and excessive charge and discharge currents (overcurrent, short circuit). Table 1 summarizes the conditions that acti-vate the protection circuit, the response of the DS2784, and the thresholds that release the DS2784 from a pro-tection state.

Overvoltage. If the voltage on VIN exceeds the overvolt-age threshold (VOV) for a period longer than overvoltage delay (tOVD), the CC pin is driven low to shut off the exter-nal-charge FET, and the OV flag in the protection register is set. The DC output remains high during overvoltage to allow discharging. When VIN falls below the charge enable threshold, VCE, the DS2784 turns the charge FET on by driving CC high. The DS2784 drives CC high before VIN < VCE if a discharge condition persists with VSNS ≥ 1.2mV and VIN < VOV.

Undervoltage. If VIN drops below the undervoltage thresh-old (VUV) for a period longer than undervoltage delay (tUVD), the DS2784 shuts off the charge and discharge Table 1. Li+ Protection Conditions and DS2784 Responses

CONDITIONOvervoltageUndervoltageOvercurrent, ChargeOvercurrent, Discharge

Short Circuit

ACTIVATION

THRESHOLDVIN > VOVVIN < VUVVSNS < VCOCVSNS > VDOCVSNS > VSC

DELAYtOVDtUVDtOCDtOCDtSCD

RESPONSE(2)

CC OffCC Off, DC Off, Sleep ModeCC Off, DC Off

DC OffDC Off

RELEASE THRESHOLDVIN < VCE or (VSNS > 1.2mV

and VIN < VOV)

VPLS > VIN(3)(charger connected)VPLS < VDD - VTP (4)(charger removed)VPLS > VDD - VTP (5)(load removed)VPLS > VDD - VTP (5)(load removed)

Note 1: All voltages are with respect to VSS.

Note 2: CC pin driven to VOLCC (VDD) for CC off response. DC pin driven to VOLDC (VSS) for DC off response.

Note 3: If VIN < VUV when charger connection is detected, release is delayed until VIN ≥ VUV. The recovery charge path provides

an internal current limit (IRC) to safely charge the battery. If the device does not enter sleep mode for an UV condition (UVEN=0) then the FETs will turn on once VIN > VUV.

Note 4: With test current ITST flowing from PLS to VSS (pulldown on PLS) enabled.Note 5: With test current ITST flowing from VDD to PLS (pullup on PLS).

VINVOVVCEVUV

DISCHARGEVSNSCHARGECCtOVDtOVDtOCDtUVDVSCVDOC0-VCOCVCPVDDVCPVPLSACTIVESLEEP

DCPOWERMODEtSCDtOCDtUVDDS2784

1-Cell Fuel Gauge with FuelPack,Protector, and SHA-1 Authentication

OV—Overvoltage Flag. OV is set to indicate that an overvoltage condition has been detected. The voltage on VIN has persisted above the VOV threshold for tOV. OV remains set until written to a 0 or cleared by a power-on reset or transi-tion to Sleep mode.

UV—Undervoltage Flag. UV is a read-only mirror of the UVF flag located in the status register. UVF is set to indicate that VIN < VUV. The UVF bit must be written to 0 to clear UV and UVF.

COC—Charge Overcurrent Flag. COC is set to indicate that an overcurrent condition has occurred during a charge. The sense-resistor voltage has persisted above the VCOC threshold for tOC. COC remains set until written to a 0, cleared by a power-on reset, or transition to Sleep mode.

DOC—Discharge Overcurrent Flag. DOC is set to indicate that an overcurrent condition has occurred during a discharge. The sense-resistor voltage has persisted above the VDOC threshold for tOC. DOC remains set until written to a 0, cleared by a power-on reset, or transition to Sleep mode.

CC—Charge Control Flag. CC indicates the logic state of the CC pin driver. CC flag is set to indicate CC high. CC flag is cleared to indicate CC low. CC flag is read only.

DC—Discharge Control Flag. DC indicates the logic state of the DC pin driver. DC flag is set to indicate DC high. DC flag is cleared to indicate DC low. DC flag is read only.

CE—Charge Enable Bit. CE must be set to allow the CC pin to drive the charge FET to the on state. CE acts as an enable input to the safety circuit. If all safety conditions are met AND CE is set, the CC pin drives to VCP. If CE is cleared, the CC pin is driven low to disable the charge FET.DE—Discharge Enable Bit. DE must be set to allow the DC pin to drive the discharge FET to the on state. DE acts as an enable input to the safety circuit. If all safety conditions are met AND DE is set, the DC pin drives to VCP. If DE is cleared, the DC pin is driven low to disable the charge FET.

Protector Threshold Register Format

The 8-bit threshold register consists of bit fields for setting the overvoltage threshold, charge overcurrent threshold, discharge overcurrent threshold, and short-circuit threshold for the protection circuit.

ADDRESS 7Fh

BIT 7VOV4

BIT 6VOV3

BIT 5VOV2

BIT 4VOV1

BIT 3VOV0

BIT 2SC0

BIT 1OC1

BIT 0OC0

Table 2. VOV Threshold

VOV BIT FIELD

0 0 0 0 00 0 0 0 10 0 0 1 00 0 0 1 10 0 1 0 00 0 1 0 10 0 1 1 00 0 1 1 1