SMBus Communication

20041540

Note 1: Absolute Maximum Ratings indicate limits beyond which damage to the device may occur. DC and AC electrical specifications do not apply when operating

the device beyond its rated operating conditions.

Parasitic components and or ESD protection circuitry are shown in the figure below for the LM89’s pins. The nominal breakdown voltage of D3 is 6.5 V. Care should

be taken not to forward bias the parasitic diode, D1, present on pins: D+, D−. Doing so by more than 50 mV may corrupt a temperature measurements.

Pin Name

PIN #

D1

D2

D3

D4

D5

D6

D7

R1

SNP

ESD CLAMP

V

DD

1

x

D+

2

x

x

xxx

x

D−

3

x

x

xxx

x

T_CRIT_A

4x

x

x

ALERT

6x

x

x

SMBData

7

x

x

x

SMBCLK

8

x

Note: An “x” indicates that the diode exists.

Note 3: See the URL ”http://www.national.com/packaging/“ for other recommendations and methods of soldering surface mount devices.

Note 4: Human body model, 100pF discharged through a 1.5k

Ω resistor. Machine model, 200pF discharged directly into each pin.

Note 5: Thermal resistance junction-to-ambient when attached to a printed circuit board with 2 oz. foil:

– SOIC-8 = 168˚C/W

– MSOP-8 = 210˚C/W

Note 7: Limits are guaranteed to National’s AOQL (Average Outgoing Quality Level).

Note 8: Local temperature accuracy does not include the effects of self-heating. The rise in temperature due to self-heating is the product of the internal power

dissipation of the LM89 and the thermal resistance. See (Note 5) for the thermal resistance to be used in the self-heating calculation.

Note 9: Quiescent current will not increase substantially with an SMBus.

Note 10: This specification is provided only to indicate how often temperature data is updated. The LM89 can be read at any time without regard to conversion state

(and will yield last conversion result).

Note 11: Default values set at power up.

SMBData and SMBCLK pins to a high impedance state.

20041513

FIGURE 1. ESD Protection Input Structure

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