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DEVICE INFORMATION
1
2
3
4
5
6
7
8
16
15
14
13
12
11
10
9
SCLK
SDA
SMBALERT
A0
A1
PWM-MODE
IN+
IN-
PWM-OUT
TACH
OVR
NC
GND
V
DD
THERM
FAN-FAULT
AMC6821
SSOP-16
(bodysize:5mmx4mm)
AMC6821
SBAS386C – MAY 2006 – REVISED JULY 2007
Table 1. TERMINAL FUNCTIONS
NAME PIN NO. DESCRIPTION
PWM-OUT 1 Digital output, open-drain. PWM output to control fan speed.
TACH 2 Digital input. Fan tachometer input to measure the fan speed.
Digital output, open-drain, active low. Goes low when temperature reaches the critical shutdown
OVR 3
threshold or remote temperature sensor failed. (See the Interrupt section for details.)
NC 4 Not connected. Reserved for manufacturer's testing.
GND 5 System ground
V
DD
6 Power supply, +3 to +5V
Digital input/output (open-drain). As an output, an active low output indicates the temperature over the
THERM 7 THERM temperature limit. As an input, the pin provides an external fan control. When the pin is pulled
low by external signal, the THERM-IN bit is set, and the fan is set to full-speed.
FAN-FAULT 8 Digital open-drain output. Goes low when a fan failure is detected.
IN – 9 Negative analog differential input. Connected to cathode of external temperature-sensing diode.
Positive analog differential input. Connected to anode of external temperature-sensing diode
IN+ 10
Pentium-IV™ substrate transistor or general-purpose 2N3904 type transistor.
PWM mode selection. When tied low (GND), the high PWM frequency range (1kHz to 40kHz) is
PWM-MODE 11 selected. When tied to V
DD
or floated, the low PWM frequency range (10Hz to 94Hz) is selected.
Checked only on power-up or reset.
Device slave address selection pin (see the SMB Interface section for details). Checked only on
A1 12
power-up or reset.
Device slave address selection pin (see the SMB Interface section for details). Checked only on
A0 13
power-up or reset.
SMBALERT 14 Digital output, open-drain, SMBALERT, active low. Requires a pull-up resistor (2.2k Ω typical).
SDA 15 Bi-directional digital I/O pin, SMBus data, open-drain. Requires a pull-up resistor (2.2k Ω typical).
SCLK 16 Digital input, SMBus clock. Requires a pull-up resistor (2.2k Ω typical).
Copyright © 2006 – 2007, Texas Instruments Incorporated Submit Documentation Feedback 5
Product Folder Link(s): AMC6821