AD7416ARMZ-REEL7 View Datasheet(PDF) - Analog Devices

Part Name

Description

Manufacturer

AD7416ARMZ-REEL7

10-Bit Digital Temperature Sensor (AD7416) and Four Single-Channel ADCs (AD7417/AD7418)

Analog Devices 

AD7416/AD7417/AD7418

Figure 5 shows the method the AD7416/AD7417/AD7418 uses

to measure the device temperature. To measure ⌬VBE, the sen-

sor (substrate transistor) is switched between operating currents

of I and N × I. The resulting waveform is passed through a

chopper-stabilized amplifier that performs the functions of

amplification and rectification of the waveform to produce a dc

voltage proportional to ⌬VBE.

This voltage is measured by the ADC to give a temperature

output in 10-bit twos complement form.

The temperature resolution of the ADC is 0.25°C, which corre-

sponds to 1 LSB of the ADC. The ADC can theoretically measure

a temperature span of 255°C; the guaranteed temperature range

is –40°C to +125°C. The result of the conversion is stored in

the Temperature Value Register (00h) as a 16-bit word. The

10 MSBs of this word store the temperature measurement (see

Table III and Table IV).

The temperature conversion formula using the 10 MSBs of the

Temperature Value Register is

1. Positive Temperature = ADC Code/4

2. Negative Temperature = (ADC Code* – 512)/4

*MSB is removed from the ADC Code.

INTERNAL REGISTER STRUCTURE

The AD7417/AD7418 has seven internal registers, as shown in

Figure 6. Six of these are data registers and one is an Address

Pointer Register. The AD7416 has five internal registers (the

ADC and Config2 Registers are not applicable to the AD7416).

TEMPERATURE

VALUE

REGISTER

(READ-ONLY

ADDRESS 00h)

CONFIGURATION

REGISTER

(READ/WRITE

ADDRESS 01h)

ADDRESS POINTER

REGISTER

(SELECTS DATA REGISTER

FOR READ/WRITE)

ADDRESS

THYST SETPOINT

REGISTER

(READ/WRITE

ADDRESS 02h)

TOTI SETPOINT

REGISTER

(READ/WRITE

ADDRESS 03h)

ADC

REGISTER

(READ-ONLY

ADDRESS 04h)

CONFIG2

REGISTER

(READ/WRITE

ADDRESS 05h)

DATA

SERIAL

BUS

INTERFACE

SDA

SCL

Figure 6. AD7417/AD7418 Register Structure

ADDRESS POINTER REGISTER

The Address Pointer Register is an 8-bit register that stores an

address that points to one of the six data registers. The first data

byte of every serial write operation to the AD7416/AD7417/

AD7418 is the address of one of the data registers, which is

stored in the Address Pointer Register, and selects the data

register to which subsequent data bytes are written. Only the

three LSBs of this register are used to select a data register.

Table I. Address Pointer Register

P7* P6* P5* P4* P3* P2 P1 P0

0

0

0

0

0

Register Select

*P3 to P7 must be set to 0.

Table II. Register Addresses

P2

P1

P0

Registers

0

0

0

Temperature Value (Read-Only)

0

0

1

Config Register (Read/Write)

0

1

0

THYST (Read/Write)

0

1

1

TOTI

1

0

0

ADC (AD7417/AD7418 Only)

1

0

1

Config2 (AD7417/AD7418 Only)

TEMPERATURE VALUE REGISTER (ADDRESS 00h)

The Temperature Value Register is a 16-bit, read-only register

whose 10 MSBs store the temperature reading from the ADC in

10-bit twos complement format. Bits 5 to 0 are unused.

Table III. Temperature Value Register

D15 D14 D13 D12 D11 D10 D9 D8 D7 D6

MSB B8 B7 B6 B5 B4 B3 B2 B1 LSB

The temperature data format is shown in Table IV. This shows

the full theoretical range of the ADC from –128°C to +127°C,

but in practice, the temperature measurement range is limited

to the operating temperature range of the device.

Table IV. Temperature Data Format

Temperature

–128°C

–125°C

–100°C

–75°C

–50°C

–25°C

–0.25°C

0°C

+0.25°C

+10°C

+25°C

+50°C

+75°C

+100°C

+125°C

+127°C

Digital Output

10 0000 0000

10 0000 1100

10 0111 0000

10 1101 0100

11 0011 1000

11 1001 1100

11 1111 1111

00 0000 0000

00 0000 0001

00 0010 1000

00 0110 0100

00 1100 1000

01 0010 1100

01 1001 0000

01 1111 0100

01 1111 1100

–10–

REV. G

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