© 2002 Microchip Technology Inc.

DS21413B-page 5

TC3404

2.0

PIN DESCRIPTIONS

Thedescriptionsof the pins arelistedinTable2-1.

TABLE 2-1:

PIN FUNCTION TABLE

Pin No.

(16-Pin PDIP

(16-Pin QSOP)

Symbol

Description

1

IN1+

Analog Input. This is the positive terminal of a true differential input with the negative

input tied internally to GND. See Section 1.0, Electrical Characteristics.

2

IN2+

Analog Input. This is the positive terminal of a true differential input with the negative

input tied internally to GND. See Section 1.0, Electrical Characteristics.

3

IN3+

Analog Input. This is the positive terminal of a true differential input consisting of

4

IN3-

Analog Input. This is the negative terminal of a true differential input consisting of

See Section 1.0, Electrical Characteristics.

5

IN4+

Analog Input. This is the positive terminal of a true differential input consisting of

6

IN4-

Analog Input. This is the negative terminal of a true differential input consisting of

See Section 1.0, Electrical Characteristics.

Analog Input. The converter’s reference voltage is the differential between this pin and

8

GND

Ground Terminal.

Analog Output. The internal reference connects to this pin. It may be scaled externally,

taken in connecting external circuitry to this pin. This pin is in a high impedance state

during Sleep mode. See Section 1.0, Electrical Characteristics.

10

SDAT

Digital Output (push-pull). This is the microPort™ serial data output. SDAT is driven low

while the TC3404 is converting data, effectively providing a “busy” signal. After the

conversion is complete, every high to low transition on the SCLK pin puts a bit from the

resultingdatawordon the SDAT pin(from MSB toLSB).

11

PFO

Digital Output (open drain). This is the output of the internal threshold detector.

When PFI is less than the internal reference, PFO is driven low.

12

PFI

Analog Input. This is the positive input to an internal comparator used as a threshold

detector. The negative input is tied to an internal reference.

13

A1

Digital Input. Controls analog multiplexer in conjunction with A0 to select one of the four

Input channels. This address is latched at the falling edge of the SCLK, which starts an

A/D conversion. A1, A0 = 00 = Input 1; 01 = Input 2; 10 = Input 3; 11 = Input 4.

14

A0

Digital Input. Controls analog multiplexer in conjunction with A1 to select one of four

Input channels. This address is latched at the falling edge of the SCLK, which starts an

A/D conversion. A1, A0 = 00 = Input 1; 01 = Input 2; 10 = Input 3; 11 = Input 4.

15

SCLK

Digital Input. This is the microPort™ serial clock input. The TC3404 comes out of Sleep

mode and a conversion cycle begins when this pin is driven low. After the conversion

the A/D resolution by one bit. When the conversion is complete, the data word can be

shifted out on the SDAT pin by clocking the SCLK pin.

16

Power Supply Input.