AD7416ARMZ datasheet(19/24 Pages) AD

19 / 24 page

AD7416/AD7417/AD7418

Rev. I | Page 19 of 24

APPLICATIONS INFORMATION

SUPPLY DECOUPLING

The AD7416/AD7417/AD7418 should be decoupled with a

0.1 μF ceramic capacitor between VDD and GND. This is

particularly important if the part is mounted remote from the

power supply.

POWER-ON RESET

To ensure proper power-on reset, make sure that the supply

voltage on the VDD pin is at 0 V. Refer to the AN-588 Application

Note, AD7416/AD7417/AD7418 Power-On Reset Circuit at

www.analog.com for more information. A failed power-on reset

can prevent the default values from being loaded into the AD7416/

AD7417/AD7418 registers. If the correct values are not loaded

into the registers, then the device cannot start operating. The

output from the temperature value and ADC value registers will

be a constant value.

To restart the device operation, the registers have to be loaded

with their default values via the I2C bus. Therefore, in the event

of an inadequate power-on reset and for all three devices, the

following registers should be loaded with their default values:

•

Configuration register—default value = 0x00

•

Config2 register—default value = 0x00

•

THYST setpoint register—default value = 0x4B00

•

TOTI setpoint register—default value = 0x5500

MOUNTING THE AD7416/AD7417/AD7418

The AD7416/AD7417/AD7418 can be used for surface or air

temperature sensing applications. If the device is cemented to a

surface with thermally conductive adhesive, the die temperature

is within about 0.2°C of the surface temperature, due to the low

power consumption of the device. Take care to insulate the back

and leads of the device from the air if the ambient air

temperature is different from the surface temperature being

measured.

The GND pin provides the best thermal path to the die, so the

temperature of the die is close to that of the printed circuit

ground track. Take care to ensure that this is in close thermal

contact with the surface being measured.

As with any IC, the AD7416/AD7417/AD7418 and its associated

wiring and circuits must be kept free from moisture to prevent

leakage and corrosion, particularly in cold conditions where

condensation is more likely to occur. Water resistant varnishes

and conformal coatings can be used for protection. The small

size of the AD7416 package allows it to be mounted inside sealed

metal probes that provide a safe environment for the device.

FAN CONTROLLER

Figure 23 shows a simple fan controller that switches on a

cooling fan when the temperature exceeds 80°C and switches it

off again when the temperature falls below 75°C. The AD7416

can be used as a standalone device in this application or with a

serial bus interface if different trip temperatures are required. If the

AD7416 is used with a bus interface, the sense of OTI can be set

to active high, Q1 and R1 can be omitted, and OTI can be con-

nected directly to the gate of Q2, with R2 as the pull-up resistor.

VDD

3V TO 5.5V

12V

AD7416

10kΩ

2N3904

OR SIMILAR

LOGIC LEVEL

MOSFET RATED

TO SUIT FAN

CURRENT

Figure 23. AD7416 Used as a Fan Controller

THERMOSTAT

Figure 24 shows the AD7416 used as a thermostat. The heater

switches on when the temperature falls below THYST and

switches off again when the temperature rises above TOTI. For

this application and for comparator mode, program the OTI

output active low.

VDD

3V TO 5.5V

AD7416

10kΩ

RELAY

2N3904

OR SIMILAR

1N4001

HEATER

SUPLY

RLA1

HEATER

Figure 24. AD7416 Used as a Thermostat

AD7416ARMZ датащи(PDF) 19 Page - Analog Devices

AD7416ARMZ датащи(HTML) 19 Page - Analog Devices

Html Pages

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24

датащи скачать

ссылки URL