DS2437 データシートの表示（PDF） - Dallas Semiconductor -> Maxim Integrated

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DS2437

Smart Battery Monitor

Dallas Semiconductor -> Maxim Integrated 

DS2437

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 of output data to measured temperature. The data is

transmitted serially over the 1-Wire interface. The DS2437 can measure temperature over the range of

-55°C to +125°C in 0.03125°C increments. For Fahrenheit usage, a lookup table or conversion factor

must be used.

Note that temperature is represented in the DS2437 in terms of a 0.03125°C LSb, yielding the following

13-bit format. The 3 least significant bits of the temperature register will always be 0. The remaining 13

bits contain the two’s complement representation of the temperature in °C, with the MSb holding the sign

(S) bit. See “Memory Map” section for the TEMPERATURE REGISTER address location.

Temperature/Data Relationships Table 1

TEMPERATURE

+125°C

+25.0625°C

+1/2°C

0°C

-1/2°C

-25.0625°C

-55°C

DIGITAL OUTPUT (Binary)

01111101 00000000

00011001 00010000

00000000 10000000

00000000 00000000

11111111 10000000

11100110 11110000

11001001 00000000

DIGITAL OUTPUT (Hex)

7D00h

1910h

0080h

0000h

FF80h

E6F0h

C900h

OPERATION – MEASURING BATTERY VOLTAGE

The on-board analog-to-digital converter (ADC) has 10 bits of resolution and will perform a conversion

when the DS2437 receives a command protocol (Convert V) instructing it to do so. The result of this

measurement is placed in the 2-byte VOLTAGE REGISTER. The range for the DS2437 ADC is 0V to

10V; this range is suitable for NiCd or NiMH battery packs up to six cells and for lithium ion battery

packs of two cells. The full-scale range of the ADC is scaled to 10.23V, resulting in a resolution of 10

mV.

While the ADC has a range that extends to 0V, it is important to note that the battery voltage can also be

the supply voltage to the DS2437. As such, the accuracy of the ADC begins to degrade below battery

voltages of 2.7V, and the ability to make conversions is limited by the operating voltage range of the

DS2437.

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