SMBus Fan Control with 1°C Accurate Temperature Monitoring
Datasheet
Table 3.2 Electrical Specifications (continued)
VDD = 3.0V to 3.6V, TA = 0oC - 85oC, Typical values are at TA = 27°C unless otherwise noted
CHARACTERISTIC
SYMBOL
MIN
TYP
MAX
UNIT
CONDITIONS
Supply Current
IDD
300
uA
1 conversion / 16 seconds - DAC
Driver, no load
Supply Current
Standby Current
IDD
300
TBD
180
uA
Temp monitoring Disabled, DAC
Driver enabled, no load
ISTANDBY
μA
PWM disabled, Monitoring
disabled
Internal Temperature Monitor
Temperature Accuracy
±1
±1
±2
°C
°C
Temperature
Resolution
8 bit resolution
Conversion Time
Internal Channel
tCONV
3
ms
External Temperature Monitor
Temperature Accuracy
±0.5
±1
°C
60°C < TDIODE < 100°C,
10°C < TA < 70°C
±1
±3
°C
°C
0°C < TDIODE < 125°C
11 bit resolution
Temperature
Resolution
0.125
Conversion Time
External Channel
tCONV
21
ms
nF
pF
Ω
Diode Decoupling
Capacitor
CFILTER
CFILTER
RSERIES
2.2
Connected across External Diode
(2N3904)
Diode Decoupling
Capacitor
470
Connected across Substrate
Transistor (CPU diode)
Resistance Error
Correction
100
Series resistance in DP and DN
lines
TACH Measurement
TACH Accuracy
10
%
TACH valid
Fan Counter Clock
Frequency
90
kHz
Pulse Width Modulator Fan Driver
PWM Resolution
PWM Frequency
64
steps
Hz
fPWM
DPWM
VDAC
22
0
5k
For 64 steps, higher frequencies
are possible with reduced
resolution. See Section 6.34.
PWM Duty cycle
100
%
V
DAC Fan Driver
Output Voltage Drive
0.2
VDD - 0.2
Current Load = ±1mA
Revision 2.53 (03-13-07)
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