TC3404_05 Datasheet, PDF (5/16 Pages) Microchip Technology – +1.8V Low Power, Quad Input, 16-Bit Sigma-Delta A/D Converter with a Power Fault Monitor

TC3404
2.0 PIN DESCRIPTIONS
The descriptions of the pins are listed in Table 2-1.
TABLE 2-1: PIN FUNCTION TABLE
Pin No.
(16-Pin PDIP
(16-Pin QSOP)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
Symbol
IN1+
IN2+
IN3+
IN3-
IN4+
IN4-
REF_IN
GND
REF_OUT
SDAT
PFO
PFI
A1
A0
SCLK
V_DD
Description
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.
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.
Analog Input. This is the positive terminal of a true differential input consisting of
IN3+ and IN3-. V_IN3 = (IN3+ – IN3-). See Section 1.0, Electrical Characteristics.
Analog Input. This is the negative terminal of a true differential input consisting of
IN3+ and IN3-. V_IN3 = (IN3+ – IN3-) IN3- can swing to, but not below, ground.
See Section 1.0, Electrical Characteristics.
Analog Input. This is the positive terminal of a true differential input consisting of
IN4+ and IN4-. V_IN4 = (IN4+ – IN4-). See Section 1.0, Electrical Characteristics.
Analog Input. This is the negative terminal of a true differential input consisting of
IN4+ and IN4-. V_IN4 = (IN4+ – IN4-) IN4- can swing to, but not below, ground.
See Section 1.0, Electrical Characteristics.
Analog Input. The converter’s reference voltage is the differential between this pin and
ground times two. It may be tied directly to REF_OUT or scaled using a resistor divider.
Any user supplied reference voltage less than 1.25 may be used in place of REF_OUT.
Ground Terminal.
Analog Output. The internal reference connects to this pin. It may be scaled externally,
and tied to the REF_IN input to provide the converter’s reference voltage. Care must be
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.
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
resulting data word on the SDAT pin (from MSB to LSB).
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.
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.
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.
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.
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
starts, each additional falling edge (up to six) detected on SCLK for t₄ seconds reduces
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.
Power Supply Input.
© 2005 Microchip Technology Inc.
DS21413C-page 5