
PRODUCT SPECIFICATION
FMS2704/FMS2704L
4
REV. 1.01 12/2/99
Pin Assignments
No.
Name
No.
Name
1.
OSC1
13.
DXP1/V1
2.
OSC2
14.
DXN1/V2
3.
RST
15.
DXP2/V3
4.
THERM
16.
DXN2/V4
5.
SDA
17.
TACHA3/V5
6.
SCL
18.
TACHB3/V6
7.
VCCD
19.
VCCA
8.
INT
20.
TACHB2
9.
ADD
21.
TACHA2
10.
FAN_SPDA
22.
TACHB1
11.
FAN_SPDB
23.
TACHA1
12.
GND
24.
STANDBY
Pin Descriptions
Pin Name
Pin No.
Type/Value
Pin Function Description
Analog I/O (11)
DXP1/V1
13
Voltage input/
current source
External diode input/V1 sense.
DISXD1 = 0: Current source to remote thermal diode 1 anode and
voltage sense input.
DISXD1 = 1: V1 voltage sense input (0–1000mV)
DXN1/V2
14
Voltage input/
current sink
External diode input/V2 sense.
DISXD1 = 0: Current sink from remote thermal diode 1 cathode and
voltage sense input.
DISXD1 = 1: V2 voltage sense input (0–1000mV)
DXP2/V3
15
Voltage input/
current source
External diode input/V3 sense.
DISXD2 = 0: Current source to remote thermal diode 1 anode and
voltage sense input.
DISXD2 = 1: V3 voltage sense input (0–1000mV)
DXN2/V4
16
Voltage input/
current sink
External diode input/V4 sense.
DISXD2 = 0: Current sink from remote thermal diode 1 cathode and
voltage sense input.
DISXD2 = 1: V4 voltage sense input (0–1000mV)
TACHA3/V5
17
Voltage input
Fan Tachometer 5/V5 sense. Dual function pin. 10K
pull-up
TACH5 = 0: V5 Voltage input (0–1000mV)
TACH5 = 1: Tachometer TACA3 Input
TACHB3/V6
18
Voltage input
Fan Tachometer 6/V6 sense. Dual function pin.
TACH6 = 1: Tachometer TACB3 Input
TACH6 = 0: V6 Voltage input (0–1000mV)
FAN_SPDA,B
10, 11
Analog/Digital
output
Fan A, B speed control. Analog (± 2mA) or PWM (± 12mA) output
programmed from the Fan Speed Configuration Register. Analog
output is 0–2.5V. External THERM = L forces a 2.5 volt output.
OSC2-1
2, 1
Output/Input
Oscillator/Clock Inputs. Connection to 3.58MHz external
frequency reference: ceramic resonator across OSC2-1 or clock
connected to OSC1.