
DC Electrical Characteristics (Continued)
The following specifications apply for +4.25 V
DC ≤VCC ≤ +5.75 VDC,fSYSCLK = 8.33 MHz, RS = 25, unless otherwise speci-
fied. Boldface limits apply for T
A = TJ = TMIN to TMAX; all other limits TA = TJ = 25C. (Note 7)
Symbol
Parameter
Conditions
Typical
Limits
Units
(Note 8)
(Note 9)
(Limits)
FAN RPM-TO-DIGITAL CONVERTER
FAN1 and FAN2 Nominal Input
RPM (See
Section 6.0)
Divisor = 1, Fan Count = 153
(Note 12)
8800
RPM
Divisor = 2, Fan Count = 153
(Note 12)
4400
RPM
Divisor = 3, Fan Count = 153
(Note 12)
2200
RPM
Divisor = 4, Fan Count = 153
(Note 12)
1100
RPM
FAN3 Design Nominal Input RPM
Fan Count = 153 (Note 12)
4400
RPM
Internal Clock Frequency
+25C
≤ T
A ≤ +75C
22.5
20.2
kHz (min)
24.8
kHz (max)
10C
≤ T
A ≤ +100C
22.5
19.1
kHz (min)
25.9
kHz (max)
DIGITAL OUTPUTS (VID4/NTEST, NMI/IRQ)
V
OUT(1)
Logical “1” Output Voltage
I
OUT = ±5.0 mA
2.4
V (min)
V
OUT(0)
Logical “0” Output Voltage
I
OUT = ±5.0 mA
0.4
V (max)
ISA D0–D7 DIGITAL OUTPUTS
V
OUT(1)
Logical “1” Output Voltage
I
OUT = ±12.0 mA
2.4
V (min)
V
OUT(0)
Logical “0” Output Voltage
I
OUT = ±12.0 mA
0.4
V (max)
I
OUT
TRI-STATEOutput Current
V
OUT = 0VDC
0.005
1
A (max)
V
OUT = VCC
0.005
1
A (min)
OPEN DRAIN DIGITAL OUTPUTS (Power Switch Bypass, SDA, RESET, SMI, Chassis Intrusion)
V
OUT(0)
Logical “0” Output Voltage
I
OUT = 5.0 mA
0.4
V (min)
I
OH
High Level Output Current
V
OUT = VCC
0.1
100
A (max)
RESET and Chassis Intrusion
45
20
ms (min)
Pulse Width
DIGITAL INPUTS: SMI__IN, VID0–VID3, VID4/NTEST, BTI, CS, A0, A1, A2, Mode Control and Interface Inputs (IORD, IOWR,
SYSCLK), Data Lines (D0–D7), Chassis Intrusion, and Tach Pulse Logic Inputs (FAN1, FAN2, FAN3)
V
IN(1)
Logical “1” Input Voltage
2.0
V (min)
V
IN(0)
Logical “0” Input Voltage
0.8
V (max)
SERIAL BUS DIGITAL INPUTS (SCL, SDA)
V
IN(1)
Logical “1” Input Voltage
0.7xV
CC
V (min)
V
IN(0)
Logical “0” Input Voltage
0.3xV
CC
V (max)
ALL DIGITAL INPUTS EXCEPT FOR BTI
I
IN(1)
Logical “1” Input Current
V
IN = VCC
0.005
1
A (min)
I
IN(0)
Logical “0” Input Current
V
IN = 0VDC
0.005
1
A (max)
C
IN
Digital Input Capacitance
20
pF
BIT DIGITAL INPUT
I
IN(1)
Logical “1” Input Current
V
IN = VCC
1
10
A (max)
I
IN(0)
Logical “0” Input Current
V
IN = 0VDC
500
2000
A (max)
C
IN
Digital Input Capacitance
20
pF
LM79
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