Smbus communication, Figure 1. esd protection input structure, Note 1) – Rainbow Electronics LM99 User Manual

Page 6: Note 2), Note 3), Note 4), Note 6), Note 7), Note 8), Note 10)

SMBus Communication

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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.

Note 2: When the input voltage (V

) at any pin exceeds the power supplies (V

GND or V

), the current at that pin should be limited to 5 mA.

Parasitic components and or ESD protection circuitry are shown in the figure below for the LM99’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 measurement.

Pin Name

PIN #

SNP

ESD CLAMP

D+

D−

T_CRIT_A

ALERT

SMBData

SMBCLK

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, 100 pF discharged through a 1.5 k

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

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

– MSOP-8 = 210˚C/W

Note 6: Typicals are at T

= 25˚C and represent most likely parametric norm.

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 LM99 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 LM99 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.

Note 12: The output rise time is measured from (V

IN(0)

max + 0.15 V) to (V

IN(1)

min − 0.15 V).

Note 13: The output fall time is measured from (V

IN(1)

min - 0.15 V) to (V

IN(1)

min + 0.15 V).

Note 14: Holding the SMBData and/or SMBCLK lines Low for a time interval greater than t

TIMEOUT

will reset the LM99’s SMBus state machine, therefore setting

SMBData and SMBCLK pins to a high impedance state.

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FIGURE 1. ESD Protection Input Structure

LM99