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ASC7511M8

LOW-VOLTAGE 2-WIRE DIGITAL TEMPERATURE SENSOR WITH THERMAL ALARM

Unspecified 

aSC7511

Basic Operation Overview

The aSC7511 temperature sensing circuitry continuously

monitors two thermal diode base-emitter voltages, one on-

chip, called “local” and one remotely located, connected to

the D+ and D- pins. At regular intervals the aSC7511

converts both analog voltages to digital values, which are

placed into the temperature registers.

The aSC7511 has an SMBus-compatible serial interface

that allows the user to access the data in the temperature

registers at any time. In addition, the serial interface gives

the user easy access to all other aSC7511 registers to

customize operation of the device.

The aSC7511 temperature-to-digital converter has two

temperature formats, 0°C to +127°C binary and extended-

range, -55°C to +150°C, offset-binary. The local sensor

resolution is 8-bits, with an LSB of 1°C. The remote or

remote diode sensor resolution is 10-bits with an LSB of

0.25°C. The temperature range of the local and remote

sensors are controlled by bit 2 of the configuration register,

default value is 0, 0°C to 127°C.

Table 1 gives examples of the relationship between the

output digital data and the measured temperature for the

default range. Table 2 gives examples for the extended

range. All output values are offset by +64°C when in this

mode.

The aSC7511 has a Shutdown Mode that reduces the

operating current to < 20µA. This mode is controlled by

RUN / STOP, bit 6 in the configuration register.

Comparisons to limits and diode open test are suspended

until the next measurement has taken place.

Temperature

Local Sensor

Remote Sensor

>127°C

+127°C

+125°C

+100°C

+50°C

+25°C

+10°C

+1.75°C

+0.25°C

0°C

< 0°C

Digital Output (Binary)

High Byte

Low Byte

Always Zero

8-Bit Resolution 00 00 0000

10-Bit Resolution

00 0000

0111 1111 00 00 0000

0111 1111 00 00 0000

0111

0110

1101 00 00 0000

0100 00 00 0000

0011 0010 00 00 0000

0001

0000

1001 00 00 0000

1010 00 00 0000

0000 0001 11 00 0000

0000

0000

0000 01 00 0000

0000 00 00 0000

0000 0000 00 00 0000

Table 1. Relationship Between Temperature and Digital

Output, Default Range, 0°C to +127°C

Temperature

Local Sensor

Remote Sensor

+150°C

+127°C

+125°C

+100°C

+50°C

+25°C

+10°C

+1.75°C

+0.25°C

0°C

-55°C

Digital Output (Offset Binary)

High Byte

Low Byte

Always Zero

8-Bit Resolution 00 00 0000

10-Bit Resolution 00 0000

1101

1011

0110 00 00 0000

1111 00 00 0000

1011 1101 00 00 0000

1010

0111

0100 00 00 0000

0010 00 00 0000

0101 1001 00 00 0000

0100

0100

1010 00 00 0000

0001 11 00 0000

0100 0000 01 00 0000

0100 0000 00 00 0000

0000 1001 00 00 0000

Table 2. Relationship Between Temperature and Digital

Output, Extended Range, -55°C to +150°C

Power-Up Default Conditions

The aSC7511 always powers-up in the following default

state:

• Configuration Register: 00h (i.e., ALERT enabled, Run

Mode, ALERT pin selected, normal range)

• Conversion Rate: 16 per second, 08h

• All Temperature and Offset Registers: 00h

• Consecutive ALERT : 1 fault (i.e., 01h in the register)

• Local and Remote Low Limit: 0°C

• Local and Remote THERM Limit: 85°C

• THERM Hysteresis: 10°C

• Register Address Pointer: Undefined, must be set by

first write sequence.

• Normal / Extended Range: Normal

After power-up, these conditions can be reprogrammed via

the serial interface. Refer to the Serial Data Bus Operation

section to for aSC7511 programming instructions.

© Andigilog, Inc. 2006

-5-

www.andigilog.com

August 2006 - 70A04010

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