IC MONITOR SMART BATTERY 16-SSOP

DS2437S/T&R

Manufacturer Part NumberDS2437S/T&R
DescriptionIC MONITOR SMART BATTERY 16-SSOP
ManufacturerMaxim Integrated Products
DS2437S/T&R datasheet
 


Specifications of DS2437S/T&R

FunctionBattery MonitorBattery TypeSmart Batteries
Voltage - Supply2.7 V ~ 10 VOperating Temperature-40°C ~ 85°C
Mounting TypeSurface MountPackage / Case16-SSOP
Lead Free Status / RoHS StatusContains lead / RoHS non-compliant  
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FEATURES
®
Unique 1-Wire
interface requires only one
port pin for communication
Provides unique 64-bit serial number to
battery packs
Eliminates thermistors by sensing battery
temperature on-chip
On-board A/D converter allows monitoring of
battery voltage for end-of-charge and end-of-
discharge determination
On-board integrated current accumulator
facilitates gas gauging
Real-time clock in binary format
40-byte nonvolatile user memory available for
storage of user data such as gas gauge and
manufacturing information
Operating range -40°C to +85°C
Applications include portable computers,
portable/cellular phones, consumer
electronics, and handheld instrumentation
DESCRIPTION
The DS2437 Smart Battery Monitor provides several functions that are desirable to carry in a battery
pack: a means of tagging a battery pack with a unique serial number; a direct-to-digital temperature
sensor which eliminates the need for thermistors in the battery pack; an A/D converter which measures
the battery voltage and current; an integrated current accumulator, which keeps a running total of all
current going into and out of the battery; a real-time clock; and 40 bytes of nonvolatile EEPROM
memory for storage of important parameters such as battery capacity, capacity remaining, and indication
of battery cycling.
Information is sent to/from the DS2437 over a 1-Wire interface, so that only one wire (and ground) needs
to be connected from a central microprocessor to a DS2437. This means that battery packs need only
have three output connectors: battery power, ground, and the 1-Wire interface.
Because each DS2437 contains a unique silicon serial number, multiple DS2437s can exist on the same
1-Wire bus. This allows multiple battery packs to be charged or used in the system simultaneously.
Smart Battery Monitor
PIN ASSIGNMENT
DQ
1
16
NC
15
2
VAD
14
3
NC
4
13
VSENS+
5
12
VSENS-
6
11
NC
7
10
AGND
8
9
16-PIN SSOP
See Mech. Drawings Section
PIN DESCRIPTION
DQ
- Data In/Out
VAD
- General A/D input
VSENS+
- Battery current monitor input (+)
VSENS-
- Battery current monitor input (-)
NC
- No connect
GND
- Digital Ground
AGND
- Analog Ground
X2
- Connection for 32.768 kHz XTAL
X1
- Connection for 32.768 kHz XTAL
V
- Power Supply (2.7V to 10.0V)
DD
1 of 31
DS2437
VDD
NC
NC
X1
NC
X2
NC
GND
070600

DS2437S/T&R Summary of contents

  • Page 1

    FEATURES ® Unique 1-Wire interface requires only one port pin for communication Provides unique 64-bit serial number to battery packs Eliminates thermistors by sensing battery temperature on-chip On-board A/D converter allows monitoring of battery voltage for end-of-charge and end-of- ...

  • Page 2

    Applications for the smart battery pack monitor include portable computers, portable/cellular telephones, and handheld instrumentation battery packs in which it is critical to monitor real-time battery performance. Used in conjunction with a microcontroller in the battery pack or host system, ...

  • Page 3

    Control function commands may be issued which instruct the DS2437 to perform a temperature measurement or battery voltage A/D conversion. The result of these measurements will be placed in the DS2437’s memory map, and may be read by issuing a ...

  • Page 4

    OPERATION – MEASURING TEMPERATURE The DS2437 measures temperatures through the use of an onboard proprietary temperature measurement technique. The temperature reading is provided in a 13-bit, two’s complement reading, which provides 0.03125°C of resolution. Table 1 describes the exact relationship ...

  • Page 5

    Voltage is expressed in this register in scaled binary format, as outlined in Table 2. Note that while codes exist for values below 2.7V, accuracy of the ADC and the limitation on the DS2437’s supply voltage make it unlikely that ...

  • Page 6

    The current is measured by the ADC with a signed 10-bit (0.004883C) resolution, and the last completed measurement is placed in the CURRENT REGISTER in a sign-extended 2’s-complement format. This register is scaled such that a count of 205 current ...

  • Page 7

    The ICA is a scaled 8-bit (0.01C resolution) volatile binary counter which represents the amount of capacity remaining in the battery in terms of the full capacity (1C), normalized to a count of 100 an ICA count of 100 represents ...

  • Page 8

    The CCA/DCA will accumulate charging/discharging current, and the counter information will be shadowed to EEPROM each time the respective counter increments by 0.32C. The memory location is reserved for the CCA/DCA, and the entire page SHOULD NOT be written ...

  • Page 9

    OPERATION – REAL TIME CLOCK The 32.768 kHz crystal oscillator is used as the time base for the timekeeping functions. The timekeeping functions are double-buffered, allowing the master to read time without the data changing while it is being read. ...

  • Page 10

    LASERED ROM Each DS2437 contains a unique ROM code that is 64 bits long. The first 8 bits are a 1-Wire family code (DS2437 code is 1Eh). The next 48 bits are a unique serial number. The last 8 ...

  • Page 11

    CRC CODE Figure 4 ROM FUNCTIONS FLOWCHART Figure DS2437 ...

  • Page 12

    MEMORY/CONTROL FUNCTIONS FLOWCHART Figure DS2437 YES ...

  • Page 13

    MEMORY/CONTROL FUNCTIONS FLOWCHART Figure 6 Cont'd DS2437 RECALLS EEPROM PAGE INTO SP PAGE DS2437 X X ...

  • Page 14

    MEMORY MAP The DS2437’s memory is organized as shown in Figure 7. The memory consists of a scratchpad RAM and storage SRAM/EEPROM. The scratchpad helps insure data integrity when communicating over the 1-Wire bus. Data is first written to the ...

  • Page 15

    ADB = A/D Converter Busy Flag A/D conversion in progress on battery voltage conversion complete measurement being made. An A/D conversion takes approximately 10 ms Don’t care Bytes 1 and 2 of ...

  • Page 16

    DS2437 MEMORY MAP Figure 7 1-Wire BUS SYSTEM The 1-Wire bus is a system which has a single bus master and one or more slaves. The DS2437 behaves as a slave. The discussion of this bus system is broken down ...

  • Page 17

    The idle state for the 1-Wire bus is high. If for any reason a transaction needs to be suspended, the bus MUST be left in the idle state if the transaction is to resume. Infinite recovery time can occur between ...

  • Page 18

    Search ROM [F0h] When a system is initially brought up, the bus master might not know the number of devices on the 1-Wire bus or their 64-bit ROM codes. The search ROM command allows the bus master to use a ...

  • Page 19

    The bus master writes a 0-bit. This deselects ROM1 leaving ROM4 as the only device still connected. 9. The bus master reads the remainder of the ROM bits for ROM4 and continues to access the part if desired. This ...

  • Page 20

    Copy Scratchpad [48hxxh] This command copies the scratchpad page xxh into the EEPROM / SRAM memory page xxh of the DS2437. After issuing this command, the user must write a page number to direct which page of memory the scratchpad ...

  • Page 21

    INSTRUCTION DESCRIPTION Initiates temperature Convert T conversion Initiates voltage A/D Convert V conversion NOTES: 1. Temperature conversion takes second. 2. A/D conversion takes ms. 3. EEPROM write takes ms. Sample Command ...

  • Page 22

    Sample Command Sequence Table 8 Example: Bus Master issues a temperature and voltage conversion, then reads the temperature, battery voltage, battery current, all on a single DS2437. MASTER MODE DATA (LSB FIRST Presence Presence ...

  • Page 23

    Sample Command Sequence Table 9 Example: Assuming a single DS2437 is configured for its current accumulators to function, this sequence allows the Bus Master to read the three current accumulators. MASTER MODE DATA (LSB FIRST Presence TX TX ...

  • Page 24

    I/O SIGNALING The DS2437 requires strict protocols to insure data integrity. The protocol consists of several types of signaling on one line: reset pulse, presence pulse, write 0, write 1, read 0, and read 1. All of these signals, with ...

  • Page 25

    Read Time Slots The host generates read time slots when data read from the DS2437. A read time slot is initiated when the host pulls the data line from a logic high level to logic low level. ...

  • Page 26

    READ / WRITE TIMING DIAGRAM Figure DS2437 ...

  • Page 27

    DETAILED MASTER READ 1 TIMING Figure 11 RECOMMENDED MASTER READ 1 TIMING Figure DS2437 ...

  • Page 28

    ABSOLUTE MAXIMUM RATINGS* Voltage on VDD and VAD, Relative to Ground Voltage on VSENS+, VSENS-, Relative to Ground Voltage on Any Pin Relative to Ground Operating Temperature Storage Temperature Soldering Temperature * This is a stress rating only and functional ...

  • Page 29

    ELECTRICAL CHARACTERISTICS: VOLTAGE A/D CONVERTER PARAMETER SYMBOL A/D Error VAD V Input Range Input Range Input Range V DD Resolution Conversion Time t CONVV No Missing Code Temperature Range Monotonicity ELECTRICAL CHARACTERISTICS: CURRENT A/D ...

  • Page 30

    AC ELECTRICAL CHARACTERISTICS: 1-WIRE INTERFACE PARAMETER SYMBOL Time Slot t Recovery Time t Write 0 Low Time t LOW0 Write 1 Low Time t LOW1 Read Data Valid t Reset Time High t RSTH Reset Time Low t Presence Detect ...

  • Page 31

    TIMING DIAGRAMS Figure 14 1-WIRE WRITE 1 TIME SLOT 1-WIRE WRITE 0 TIME SLOT 1-WIRE READ TIME SLOT 1-WIRE RESET PULSE 1-WIRE PRESENCE DETECT DS2437 ...