Rainbow Electronics MAX999 - Manual (Page 8)

MAX961–MAX964/MAX997/MAX999
Single/Dual/Quad, Ultra-High-Speed, +3V/+5V,
Beyond-the-Rails Comparators
8 _______________________________________________________________________________________
For a large differential input voltage (exceeding 3V F ),
this protection circuitry increases the input bias current
at IN+ (source) and IN- (sink).
(IN+ - IN-) - 3V F
Input current = ————————
2 x 200
Input currents with large differential input voltages
should not be confused with input bias currents (I
B ).
As long as the differential input voltage is less than
3V
F , this input current is less than 2I B .
The input circuitry allows the MAX961–MAX964/
MAX997/MAX999’s input common-mode range to
extend 100mV beyond both power-supply rails. The
output remains in the correct logic state if one or both
inputs are within the common-mode range. Taking
either input outside the common-mode range causes
the input to saturate and the propagation delay to
increase.
t H
t SU
t
LPW
0V
V CC
V
OS
DIFFERENTIAL
INPUT
VOLTAGE
LE
Q
Q
V OL
V OH
t LPD t PD
t SKEW t SKEW
V CC
2
V CC
2
V CC
2
Figure 2. MAX961/MAX963 Timing Diagram
MAX961-MAX964
MAX997
MAX999
IN+
200 Ω
TO INTERNAL
CIRCUITRY
IN-
200 Ω
TO INTERNAL
CIRCUITRY
Figure 3. Input Stage Circuitry