Datasheet

LM81
www.ti.com SNAS011E –JUNE 1999–REVISED FEBRUARY 2002
DC ELECTRICAL CHARACTERISTICS
(1)
(continued)
The following specifications apply for +2.8VDC ≤ V+ ≤ +3.8VDC, RS = 500Ω, unless otherwise specified. Boldface limits
apply for T
A
= T
J
= T
MIN
to T
MAX
; all other limits T
A
= T
J
= 25˚C.
SYMBOL PARAMETER TEST CONDITIONS TYPICAL
(2)
LIMITS LIMITS UNIT
LM81BIM
(3)
LM81CIM
(3)
DAC Error V+ = 3.3V ±5 ±5 %
(max)
±62.5 ±62.5 mV
(max)
±10 %
(max)
±125 mV
(max)
DAC Error Temperature Sensitivity 100 100 ppm/˚C
(max)
DAC Error Power Supply 0.5 0.725 %
Sensitivity (max)
R
L
Output Load Resistance V
O
= 1.25V 625 625 Ω
(min)
C
L
Output Load Capacitance 20 20 pF
(max)
FAN RPM-TO-DIGITAL CONVERTER
Fan RPM Error +25˚C ≤ T
A
≤ +75 ˚C ±10 ±10 %
(max)
−10˚C ≤ T
A
≤ +100˚C ±15 ±15 %
(max)
−40˚C ≤ T
A
≤ +125˚C ±20 ±20 %
(max)
Full-scale Count 255 255 (max)
FAN1 and FAN2 Nominal Input Divisor = 1, Fan Count = 153 8800 RPM
RPM (See the FAN INPUTS (See
(7)
)
section)
Divisor = 2, Fan Count = 153 4400 RPM
(See
(7)
)
Divisor = 3, Fan Count = 153 2200 RPM
(See
(7)
)
Divisor = 4, Fan Count = 153 1100 RPM
(See
(7)
)
Internal Clock Frequency +25˚C ≤ T
A
≤ +75 ˚C 22.5 20.2 20.2 kHz
(min)
24.8 24.8 kHz
(max)
−10˚C ≤ T
A
≤ +100˚C 22.5 19.1 19.1 kHz
(min)
25.9 25.9 kHz
(max)
−40˚C ≤ T
A
≤ +125˚C 22.5 18 18 kHz
(min)
27 27 kHz
(max)
DIGITAL OUTPUTS (NTEST_OUT)
V
OUT(1)
Logical “1” Output Voltage I
OUT
= ± 3.0 mA at V+ = +2.8V 2.4 2.4 V
(min)
V
OUT(0)
Logical “0” Output Voltage I
OUT
= ± 3.0 mA at V+ = +3.8V 0.4 0.4 V
(max)
OPEN- DRAIN DIGITAL OUTPUTS (SMBData, RESET, CI, INT, T_CRIT_A)
(7) The total fan count is based on 2 pulses per revolution of the fan tachometer output.
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