Hysteresis

T_CRIT

Output Pin

Remote TCRIT Limit

Remote

Temperature

Status bit RCRIT

Remote TCRIT Limit -

Hysteresis

LM95235

LM95235-Q1

SNIS142F – APRIL 2006 – REVISED MARCH 2013

www.ti.com

Table 8. 11-Bit, 2's Complement (10-Bit Plus Sign)

Digital Output

Temperature

Binary

Hex

+125°C

0111 1101 0000 0000

7D00h

+25°C

0001 1001 0000 0000

1900h

+1°C

0000 0001 0000 0000

0100h

+0.125°C

0000 0000 0010 0000

0020h

0°C

0000 0000 0000 0000

0000h

-0.125°C

1111 1111 1110 0000

FFE0h

-1°C

1111 1111 0000 0000

FF00h

-25°C

1110 0111 0000 0000

E700h

-55°C

1100 1001 0000 0000

C900h

SMBDAT OPEN-DRAIN OUTPUT

The SMBDAT output is an open-drain output and does not have internal pull-ups. A “high” level will not be

observed on this pin until pull-up current is provided by some external source, typically a pull-up resistor. Choice

of resistor value depends on many system factors but, in general, the pull-up resistor should be as large as

possible without effecting the SMBus desired data rate. This will minimize any internal temperature reading

errors due to internal heating of the LM95235. The maximum resistance of the pull-up to provide a 2.1V high

level, based on LM95235 specification for High Level Output Current with the supply voltage at 3.0V, is 82 k

Ω

(5%) or 88.7 k

Ω (1%).

T_CRIT OUTPUT AND TCRIT LIMIT

The LM95235's T_CRIT pin is an active-low open-drain output that is triggered when the local and/or the remote

temperature conversion is above the limits defined by the Remote and/or Local Limit registers. The state of the

T_CRIT pin will return to the HIGH state when both the Local and Remote temperatures are below the values

programmed into the Limit Registers less the value in the Common Hysteresis Register. Additionally, if the

remote temperature exceeds the value in the Remote TCRIT Limit Register the Status Bit for Remote TCRIT

(RTCRIT), in Status Register 1, is set to 1. In the same way if the local temperature exceeds the value in the

Local Shared OS and TCRIT Limit Register the Status Bit for the Shared Local OS and TCRIT (LOC) bit in

Status Register 1 is set to 1.The T_CRIT output and the Status Register flags are updated after every Local and

Remote temperature conversion. See Figure 12

Figure 12. T_CRIT Comparator Temperature Response Diagram

14

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