Datasheet

MAX9924–MAX9927
Variable Reluctance Sensor Interfaces with
Differential Input and Adaptive Peak Threshold
_______________________________________________________________________________________ 3
PARAMETER SYMBOL CONDITIONS MIN TYP MAX UNITS
INPUT DIFFERENTIAL AMPLIFIER (MAX9924/MAX9926)
Input Voltage Range IN+, IN- Guaranteed by CMRR -0.3
V
CC
+
0.3
V
MAX9924 (Note 5) 60 87
Differential Amplifier
Common-Mode Rejection Ratio
CMRR
MAX9926 (Note 5) 55 78
dB
Input Resistance R
IN
(Note 5) 65 100 135 kΩ
ADAPTIVE PEAK DETECTION
MAX9924/MAX9925 -6.5 0 +6.5
Zero-Crossing Threshold V
ZERO_THRESH
Mode B
operation
(Notes 5, 6) MAX9926/MAX9927 -6.5 0 +10
mV
V
ADAPTIVE
Adaptive peak threshold 33 %PK
Minimum threshold of hysteresis
comparator MAX9924/MAX9926
(Notes 5, 6)
41530
Minimum threshold of hysteresis
comparator MAX9925/MAX9927
(Notes 5, 6)
20 30 50
V
MIN-THRESH
- V
ZERO-THRESH
for
MAX9924 (Notes 5, 6)
71526
V
MIN-THRESH
- V
ZERO-THRESH
for
MAX9926 (Notes 5, 6)
21530
Fixed and Adaptive Peak
Threshold
V
MIN-THRESH
V
MIN-THRESH
- V
ZERO-THRESH
for
MAX9925/MAX9927 (Notes 5, 6)
19 30 50
mV
Watchdog Timeout for Adaptive
Peak Threshold
t
WD
Timing window to reset the adaptive
peak threshold if not triggered (input
level below threshold)
45 85 140 ms
ENTIRE SYSTEM
Comparator Output Low Voltage V
COUT_OL
0.2 V
t
PDZ
Overdrive = 2V to 3V, zero-crossing
50
Propagation Delay
t
PDA
Overdrive = 2V to 3V, adaptive peak
150
ns
COUT Transition Time t
HL-LH
2ns
Propagation Delay Jitter t
PD-JITTER
Includes noise of differential amplifier
and comparator, f = 10kHz,
V
IN
= 1V
P-P
sine wave
20 ns
ELECTRICAL CHARACTERISTICS (continued)
(V
CC
= 5V, V
GND
= 0V, MAX9925/MAX9927 gain setting = 1V/V, Mode A1, V
BIAS
= 2.5V, V
PULLUP
= 5V, R
PULLUP
= 1kΩ, C
COUT
=
50pF. T
A
= T
MIN
to T
MAX
, unless otherwise noted. Typical values are at T
A
= +25°C.) (Note 2)