Datasheet

MAX9922/MAX9923
Ultra-Precision, High-Side
Current-Sense Amplifiers
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Note 1: All devices are 100% production tested at T
A
= +85°C. All temperature limits are guaranteed by design.
Note 2: V
OS
is measured in bidirectional mode with V
REF
= V
DD
/2.
Note 3: Data sheet limits are guaranteed by design and bench characterization. Thermocouple effects preclude measurement of
this parameter during production testing. Devices are screened during production testing to eliminate defective units.
Note 4: V
OS
drift limits are guaranteed by design and bench characterization and are the average of drift from -40°C to +25°C and
from +25°C to +85°C.
Note 5: V
RSB
= V
RS+
= 12V, V
REF
= V
DD
/2 for bipolar mode and V
REF
= 0V for unipolar mode. Gain accuracy and gain linearity are
specified over a V
SENSE
range that keeps the output voltage 250mV away from the rails to achieve full accuracy. Output of
the part is rail-to-rail, and goes to within 25mV of the rails, but accuracy is not maintained. Linear operation is not guaran-
teed for V
SENSE
voltages > ±150mV. See the Typical Operating Characteristics section for plots of Input vs. Output.
Note 6: This is the worst-case REF current needed to directly drive the bottom terminal of the gain setting resistors, at V
DD
= 3.3V,
and V
REF
= V
DD
/2 while maintaining gain accuracy. An internal 1kΩ resistor (R1) is present in the MAX9923T/
MAX9923H/MAX9923F between the FB and REF pins, while in the MAX9922 the resistor is external and user selectable. A
voltage identical to the V
SENSE
develops across this resistor. In all versions the REF input current is dependent on the mag-
nitude and polarity of V
SENSE
, and in the MAX9922 it is dependent on the value of the external resistor as well. The input
bias current for REF is typically 1pA in the MAX9922 since it connects to the gate of a MOS transistor. See the External
Reference section for more details.
Note 7: The range of V
REF
, V
CM
, and V
SENSE
may limit the output swing of the MAX9922 with adjustable gain set to less than
100V/V.
ELECTRICAL CHARACTERISTICS (continued)
(V
RSB
= V
RS+
= V
RS- =
+12V, V
DD
= +3.3V, V
GND
= 0V, V
REF
= V
DD
/2 for bidirectional, V
REF
= 0V for unidirectional, V
SENSE
= V
RS+
- V
RS-
=
0V, MAX9922 is set for A
V
=100V/V (R1 = 1kΩ, R2 = 99kΩ), SHDN = V
DD
, T
A
= -40°C to +85°C, unless otherwise noted. Typical values
are at T
A
= +25°C.) (Note 1)
PARAMETER SYMBOL CONDITIONS MIN TYP MAX UNITS
Power-Down Supply Current I
RSBL
V
DD
= V
REF
= 0V, V
RSB
= V
RS+
= V
RS-
= 28V 0.05 1 µA
Power-Up Time
MAX9922, A
V
= 100V/V, V
REF
= 0V, V
SENSE
=
10mV, V
DD
= 0V to 3.3V, settling to 0.1% of final
value
800 µs