MAX6698UE99+【PDF 14/24 页】IC TEMP MONITOR 7CH 16-TSSOP

收藏本站

您好，
买卖IC网欢迎您。
请登录
免费注册

买卖IC网

Sheet目录44

10页 11页 12页 13页 [14页]15页 16页 17页 18页

channel 1. The series resistance cancellation function

increases the conversion time for channel 1 by 125ms.

This feature cancels the bulk resistance of the sensor

and any other resistance in series (wire, contact resis-

tance, etc.). The cancellation range is from 0 to 100&.

Discrete Remote Diodes

When the remote-sensing diode is a discrete transistor,

its collector and base must be connected together. Table

11 lists examples of discrete transistors that are appropri-

ate for use with the MAX6698. The transistor must be a

small-signal type with a relatively high forward voltage;

otherwise, the A/D input voltage range can be violated.

The forward voltage at the highest expected temperature

must be greater than 0.25V at 10礎, and at the lowest

expected temperature, the forward voltage must be less

than 0.95V at 100礎. Large power transistors must not be

used. Also, ensure that the base resistance is less than

10&. Tight specifications for forward current gain (50 < ?/DIV>

<150, for example) indicate that the manufacturer has

good process controls and that the devices have consis-

tent V

characteristics. Manufacturers of discrete tran-

sistors do not normally specify or guarantee ideality

factor. This is normally not a problem since good-quality

discrete transistors tend to have ideality factors that fall

within a relatively narrow range. We have observed varia-

tions in remote temperature readings of less than ?癈

with a variety of discrete transistors. Still, it is good design

practice to verify good consistency of temperature read-

ings with several discrete transistors from any manufac-

turer under consideration.

Unused Diode Channels

If one or more of the remote diode channels is not need-

ed, the DXP and DXN inputs for that channel should

either be unconnected, or the DXP input should be con-

nected to V

. The status register indicates a diode

"fault" for this channel and the channel is ignored during

the temperature-measurement sequence. It is also good

practice to mask any unused channels immediately upon

power-up by setting the appropriate bits in the

Configuration 2 and Configuration 3 registers. This will

prevent unused channels from causing ALERT# or

OVERT# to assert.

Thermistor Measurements

The MAX6698 can use three external thermistors to

measure temperature. A thermistors resistance varies

as a function of temperature. A negative temperature

coefficient (NTC) thermistor can be connected between

the thermistor input and ground, with a series resistor,

REXT_, connected from the thermistor input to VREF.

7-Channel Precision Remote-Diode, Thermistor,

and Local Temperature Monitor

14 ______________________________________________________________________________________

BIT

NAME

P R TATE

FUNCTION

7 M B

Reserved

Local ALERT

Local Channel High-Alert Bit. This bit is set to logic 1 when the local temperature

exceeds the temperature threshold limit in the local ALERT high-limit register.

Thermistor 3 ALERT

Thermistor 3 Alert Bit. This bit is set to logic 1 when the thermistor 3 voltage

exceeds the threshold limit in the thermistor 3 ALERT high-limit register.

Thermistor 2 ALERT

Thermistor 2 Alert Bit. This bit is set to logic 1 when the thermistor 2 voltage

exceeds the threshold limit in the thermistor 2 ALERT high-limit register.

Thermistor 1 ALERT

Thermistor 1 Alert Bit. This bit is set to logic 1 when the thermistor 1 voltage

exceeds the threshold limit in the thermistor 1 ALERT high-limit register.

Remote-Diode 3

ALERT

Channel 3 Remote-Diode High-Alert Bit. This bit is set to logic 1 when the

channel 3 remote-diode temperature exceeds the programmed temperature

threshold limit in the remote 3 ALERT high-limit register.

Remote-Diode 2

ALERT

Channel 2 Remote-Diode High-Alert Bit. This bit is set to logic 1 when the

channel 2 remote-diode temperature exceeds the temperature threshold limit in

the remote 2 ALERT high-limit register.

Remote-Diode 1

ALERT

Channel 1 Remote-Diode High-Alert Bit. This bit is set to logic 1 when the

channel 1 remote-diode temperature exceeds the temperature threshold limit in

the remote 1 ALERT high-limit register.

Table 8. Status 1 Register

发布紧急采购，3分钟左右您将得到回复。

采购需求

(若只采购一条型号，填写一行即可)

*型号	*数量	厂商	批号	封装

添加更多采购

采购需求

发布成功！您可以继续发布采购。也可以进入我的后台，查看报价

发布成功！您可以继续发布采购。也可以进入我的后台，查看报价

我的联系方式