AMC80

SBOS559B – MAY 2011 – REVISED OCTOBER 2015

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Feature Description (continued)

7.3.2 Temperature Measurement

The AMC80

ΔVBE-type temperature sensor, is a ΔΣ ADC that performs 9-bit or 12-bit twos complement

temperature conversions. An 8-bit comparator that compares the readings to the user-programmable hot and

overtemperature setpoints, and hysteresis values is also incorporated into the AMC80.

Temperature data can be read from the Temperature Reading Register (address 27h). Temperature limits can be

read from and written to the Hot Temperature (THOT), Hot Temperature Hysteresis (THOT_HYST), OS Temperature

(TOS), and OS Temperature Hysteresis (TOS_HYST) Limit Registers (addresses 38h to 3Bh). Each limit is

represented in 12-bit, 9-bit, or 8-bit resolution, as shown in Table 1.

Table 1. Temperature Lookup

12-BIT DIGITAL OUTPUT (HEX)

9-BIT DIGITAL OUTPUT (HEX)

8-BIT DIGITAL OUTPUT (HEX)

TEMPERATURE

LSB = 0.0625°C

LSB = 0.5°C

LSB = 1°C

+125°C

07D

0FA

7D

+25°C

019

032

19

+1°C

010

003

01

0.0625°C

001

—

—

0°C

000

000

00

–0.0625°C

FFF

—

—

–1°C

FF0

1FF

FF

–25°C

E70

1CE

E7

–55°C

C90

192

C9

When using a single-byte read, the eight MSBs of the temperature reading can be found in the Value RAM

Register

(address

27h).

The

remainder

of

the

temperature

reading

can

be

found

in

the

OS

Configuration/Temperature Resolution Register (address 06h), bits 4 to 7. In 9-bit format, bit 7 is the only valid

bit. In addition, all nine or 12 bits can be read using a double-byte read at register address 27h.

There are four Value RAM Register limits for the temperature reading that affect the INT and OS outputs of the

AMC80. These are the THOT, THOT_HYST, TOS, TOS_HYST Limit Registers (addresses 38h to 3Bh); see Table 15.

There are three interrupt modes of operation: Default Interrupt, One-Time Interrupt, and Comparator. The OS

output of the AMC80 can be programmed for One-Time Interrupt mode and Comparator mode. INT can be

programmed for Default Interrupt mode and One-Time Interrupt mode. These modes are explained in the

following subsections.

7.3.2.1 Default Interrupt Mode

In Default Interrupt mode, exceeding THOT causes an interrupt that remains active indefinitely until reset by

reading Interrupt Status Register 1 (address 01h) or cleared by the INT_Clear bit in the Configuration Register

(address 00h, bit 3). When an interrupt event has occurred by exceeding THOT, and is then reset, another

interrupt occurs again when the next temperature conversion has completed. The interrupts continue to occur in

this manner until the temperature falls below THOT_HYST, at which time the interrupt output automatically clears.

7.3.2.2 One-Time Interrupt Mode

In One-Time Interrupt mode, exceeding THOT causes an interrupt that remains active indefinitely until reset by

reading Interrupt Status Register 1 or cleared by the INT_Clear bit in the Configuration Register. When an

interrupt event has occurred by exceeding THOT, and is then reset, an interrupt does not occur again until the

temperature falls below THOT_HYST.

7.3.2.3 Comparator Mode

In Comparator mode, exceeding TOS causes the OS output to go low (default) and remain low until the

temperature falls below TOS_HYST. When the temperature falls below TOS_HYST, OS goes high.

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