SMBus DIGITAL SWITCHING CHARACTERISTICS

Unless otherwise noted, these specifications apply for V

pF. Boldface limits apply for T

The switching characteristics of the LM90 fully meet or exceed the published specifications of the SMBus version 2.0. The fol-

lowing parameters are the timing relationships between SMBCLK and SMBData signals related to the LM90. They adhere to

but are not necessarily the SMBus bus specifications.

Symbol

Parameter

Conditions

Typical

Limits

Units

(Note 6)

(Note 7)

(Limit)

t

SU;STA

SMBus Repeated Start-Condition Setup

Time, SMBCLK High to SMBData Low

0.6

µs (min)

t

BUF

SMBus Free Time Between Stop and Start

Conditions

1.3

µs (min)

SMBus Communication

20033740

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 LM90’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:

– MSOP-8 = 210˚C/W

20033713

FIGURE 1. ESD Protection Input Structure

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