MIC74 Datasheet, PDF (2/20 Pages) Micrel Semiconductor – 2-Wire Serial I/O Expander and Fan Controller Advance Information

MIC74
Pin Configuration
A0 1
A1 2
A2 3
P0 4
P1 5
P2 6
P3 7
GND 8
16 VDD
15 DATA
14 CLK
13 /ALERT
12 P7 (/FS2)
11 P6 (/FS1)
10 P5 (/FS0)
9 P4 (/SHDN0)
16-Lead QSOP
Micrel
Pin Description
Pin Number
1–3
4–7
8
9–12
13
14
15
16
Pin Name
A0–A2
P0–P3
GND
P4–P7 (/SHDN, /FS0–/FS2)
/ALERT
CLK
DATA
VDD
Pin Function
Address (Input): Slave address selection inputs; sets the three least signifi-
cant bits of the MIC74’s slave address.
Parallel I/O (Input/Output): General-purpose I/O pin. Direction and output
type are user programmable.
Ground
Parallel I/O (Input/output): P4–P7 are general-purpose I/O pins. Direction
and output type are user programmable.
Shutdown (Output): When the FAN bit is set, pin 9 becomes SHDN.
Fan Speed (Output): When the FAN bit is set, pins 10 through 12 become /
FS0–/FS2 respectively, controlled by the FAN_SPEED register.
Interrupt (Output): Active-low, open-drain output signals input-change-
interrupts to the host on this pin. Signal is cleared when the bus master
(host) polls the ARA (alert response address = 0001 100) or reads status.
Serial Bus Clock (Input): The host provides the serial bit clock in this input.
Serial Data (Input/Output): Serial data input and open-drain serial data
output.
Power Supply (Input.)
MIC74
2
August 1, 2000