User Manual

DC Electrical Characteristics (Continued)
The following specifications apply for +2.8V
DC
≤ V
+
≤ +3.8V
DC
,R
S
= 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. (Note 8)
Symbol Parameter Conditions
Typical Limits
LM81BIM
Limits
LM81CIM
Units
(Note 9) (Note 10) (Note 10) (Limits)
DAC CHARACTERISTICS
Resolution 8 Bits
DAC Error V
+
= 3.3V
±
5
±
62.5
±
10
±
125
±
5
±
62.5
% (max)
mV (max)
% (max)
mV (max)
DAC Error Temperature
Sensitivity 100 100 ppm/˚C (max)
DAC Error Power Supply
Sensitivity 0.5 0.725 % (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
RPM (See
Section 6.0 )
Divisor = 1, Fan Count =
153 (Note 14)
8800 RPM
Divisor = 2, Fan Count =
153 (Note 14)
4400 RPM
Divisor = 3, Fan Count =
153 (Note 14)
2200 RPM
Divisor = 4, Fan Count =
153 (Note 14)
1100 RPM
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
27
18
27
kHz (min)
kHz (max)
LM81
www.national.com 6