MCP960X datasheet(44/57 Pages) MICROCHIP

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DS20005426G-page 44

MCP960X/L0X/RL0X

6.3

Device Features

6.3.1

I2C ADDRESSING

The MCP960X/L0X/RL0X supports up to eight devices

on the I2C bus. Applications, such as large thermal

management racks with several thermocouple sensor

interfaces, are able to monitor various temperature

zones with minimal pin count microcontrollers. This

reduces the total solution cost, while providing a highly

accurate thermal management solution using the

MCP960X/L0X/RL0X.

FIGURE 6-4:

I2C Address Selection

Implementation.

6.3.2

INPUT IMPEDANCE

The MCP960X/L0X/RL0X uses a switched capacitor

amplifier input stage to gain the input signal to a

maximum resolution of 2 µV/LSb at an 18-bit ADC

setting. An internal input capacitor is used for charge

storage. The differential input impedance, ZIN_DF, is

dominated by the sampling capacitor and the switched

capacitor amplifier sampling frequency. During a

sampling period, the charging and discharging of the

sampling capacitor creates dynamic input currents at the

input pins. Adding a 10-100 nF capacitor between the

inputs can improve stability.

Since the sampling capacitor is only switching to the

input pins during a conversion process, the input

impedance is only valid during conversion periods.

During Low-Power or Shutdown mode, the input

amplifier stage is disabled; therefore, the input

impedance is ZIN_CM, which is due to the leakage

current from ESD protection diodes, as shown in

Figure 6-5.

FIGURE 6-5:

Thermocouple Input Stage.

MCP960X/L0X/RL0X

PIC®

I2C

Alert

GND

Types K, J, T, N,

E, B, S, R

VDD

Alert

GND

VDD

MCP960X/L0X/RL0X

R7A R7B

R2A R2B

TABLE 6-2:

RECOMMENDED

RESISTOR VALUES FOR

I2C ADDRESSING

Device #

Command

Byte

Values

RXA (k)RXB (k)

1100 000x

ADDR Pin Tied to GND

1100 001x

R2A = 10

R2B = 2.2

1100 010x

R3A = 10

R3B = 4.3

1100 011x

R4A = 10

R4B = 7.5

1100 100x

R5A = 10

R5B = 13

1100 101x

R6A = 10

R6B = 22

1100 110x

R7A = 10

R7B = 43

1100 111x

ADDR Pin Tied to VDD

Note:

Standard 5% tolerance resistors are used in

the table; however, 1% tolerance resistors

provide better ratio matching.

ADDR

VIN+

VIN-

VIN+

VIN-

Microcontroller

Unit 2/8

Unit 7/8

Types K, J, T, N,

E, B, S, R

Up to Eight Devices

on the I2C Bus

RSS

VIN+,VIN-

Sampling

Switch

CSAMPLE

(3.2 pF)

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