EMC1428 datasheet(21/47 Pages) SMSC

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1°C Multiple Temperature Sensor with HW Thermal Shutdown & Hottest of Thermal Zones

Datasheet

SMSC EMC1428

Revision 0.62 (03-05-08)

DATASHEET

4.6

Diode Connections

The diode connection for the External Diode 1 channel is determined based on the selected device.

For the EMC1428, this channel can support a diode-connected transistor (such as a 2N3904) or a

substrate transistor (such as those found in an CPU or GPU) as shown in Figure 4.4. Anti-parallel

diodes are not supported on the External Diode 1 channel.

4.6.1

Diode Faults

The EMC1428 actively detects an open and short condition on each measurement channel. When a

diode fault is detected, the temperature data MSByte is forced to a value of 80h and the FAULT bit is

set in the Status Register. When an external diode channel is configured to operate in APD mode, the

circuitry will detect independent open fault conditions, however a short condition will be shared

between the APD channels.

Table 4.2 Supply Current vs. Conversion Rate for EMC1428

CONVERSION RATE

AVERAGE SUPPLY CURRENT

AVERAGING FACTOR (BASED ON

11-BIT OPERATION)

DYNAMIC

AVERAGING

ENABLED

(DEFAULT)

DYNAMIC

AVERAGING

DISABLED

DYNAMIC

AVERAGING

ENABLED

(DEFAULT)

DYNAMIC

AVERAGING

DISABLED

1 / sec

715uA

450uA

2 / sec

750uA

550uA

4 / sec (default)

900uA

815uA

Continuous (see Table 5.8)

950uA

0.5x

Figure 4.4 Diode Connections

Local Ground

Typical remote

substrate transistor

i.e. CPU substrate PNP

Typical remote

discrete PNP transistor

i.e. 2N3906

Typical remote

discrete NPN transistor

i.e. 2N3904

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