Microchip Technology MCP3421DM-WS Data Sheet

DS22003E-page 10

© 2009 Microchip Technology Inc.

 

SDA is the serial data pin of the I

2

C interface. The SDA

pin is used for input and output data. In read mode, the
conversion result is read from the SDA pin (output). In
write mode, the device configuration bits are written
(input) though the SDA pin. The SDA pin is an open-
drain N-channel driver. Therefore, it needs a pull-up
resistor from the V

DD

 line to the SDA pin. Except for

start and stop conditions, the data on the SDA pin must
be stable during the high period of the clock. The high
or low state of the SDA pin can only change when the
clock signal on the SCL pin is low. Refer to 

C Serial Communications” for more details of I

2

C

Serial Interface communication. 

Typical range of the pull-up resistor value for SCL and
SDA is from 5 k

Ω to 10 kΩ for standard (100 kHz) and

fast (400 kHz) modes, and less than 1 k

Ω for high

speed mode (3.4 MHz). The High-Speed mode is not
recommended for V

DD

 less than 2.7V.

 

C

PIN

V

R

SS

V

IN

+,V

IN

-

4 pF

V

T

 = 0.6V

V

T

 = 0.6V

I

LEAKAGE

Sampling
Switch

SS

R

S

C

SAMPLE

(3.2 pF)

V

DD

(~ ±1 nA)

Legend:

V

=

Signal Source

I

LEAKAGE

=

Leakage Current at Analog Pin

R

SS

=

Source Impedance

SS

=

Sampling Switch

V

IN

+, V

IN

-

=

Analog Input Pin

R

S

=

Sampling Switch Resistor

C

PIN

=

Input Pin Capacitance

C

SAMPLE

=

Sample Capacitance

V

T

=

Threshold Voltage

D

1

, D

2

 =

ESD Protection Diode

D

1

D

2

V

SS