MAX9937EVKIT+ Maxim Integrated Products, MAX9937EVKIT+ Datasheet - Page 9

• Manufacturer Part Number: MAX9937EVKIT+
• Description: EVAL KIT FOR MAX9937
• Manufacturer: Maxim Integrated Products

Specifications of MAX9937EVKIT+

• Channels Per Ic: 1 - Single
• Amplifier Type: Current Sense
• Output Type: Single-Ended
• -3db Bandwidth: 350kHz
• Current - Output / Channel: 22mA
• Operating Temperature: -40°C ~ 125°C
• Current - Supply (main Ic): 20µA
• Voltage - Supply, Single/dual (±): 2.7 V ~ 5.5 V
• Board Type: Fully Populated
• Utilized Ic / Part: MAX9937
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant
• Slew Rate: -

In this case, R
tolerance of the R
set current of the amplifier.
The temperature drift of these parameters similarly add
up to give a final result.
Shown below is an example calculation of V
+25°C:
With V
±12% (max) of 5.6µA (max) = ±0.67µA (max), and R
= 500Ω with ±1% tolerance (i.e., ΔR
V
Real-world applications of current-sense amplifiers
need to measure currents precisely in the presence of
a wide variety of input transients. For example, fast
load-current transients when measuring at the input of a
switching buck regulator can cause high-frequency dif-
ferential sense voltages to occur at inputs of the
MAX9937, although the signal of interest is the average
DC value. Alternately, parasitic voltage pickup on a dis-
connected or long cable can cause common-mode
voltage transients to occur at inputs of the MAX9937,
which are required to be rejected effectively.
Figure 1. Typical Application Circuit with Optional External Filtering
OS-FINAL
OS
= ±1.2mV (max), I
= 1.25mV (max).
RS
= R
RS
_______________________________________________________________________________________
RSP
resistors used, and ΔI
V
GAIN = V
BAT
TO 28V
= 4V
= R
V
SENSE
OUT
Flexible EMI Filtering
Automotive Current-Sense Amplifier
RSN
*FILTER CAPACITORS ARE OPTIONAL.
B
= R
, ΔR
= 5.6µA (max), ΔI
R
OUT
RSP
GND
RS
RS
MAX9937
with Reverse-Battery Protection
= ±5Ω max)
depends on the
R
499Ω
10kΩ
R
B
RSP
OUT
RSP
= input off-
RS+
OUT
OS
C
OUT
B
R
1nF
220nF
SENSE
C
RS
*
at
IN
=
*
RS-
The MAX9937 allows two methods of filtering to help
improve performance in the presence of input common-
mode voltage and input differential-voltage transients
(see Figure 1).
The capacitor C
against input differential voltages, and prevents them
from reaching the MAX9937. The corner frequency of
this filter is determined by the choice of R
Similarly, capacitor C
ter the output voltage, thus providing not only differen-
tial filtering, but also filtering for input common-mode
transients that have made it past the MAX9937. The
corner frequency of this filter is similarly determined by
choice of R
current-output device, and has the ability to drive an
infinite amount of load capacitance.
RSN
BLOCK
R
499Ω
BIAS
RSN
V
CC
OUT
f
C OUT
−
MICROCONTROLLER
f
IN
C IN
and C
−
ADC
between RS+ and RSN helps filter
OUT
=
=
5V
2π
OUT
2π
LOAD
from OUT to ground helps fil-
R
R
OUT
. Note: The MAX9937 is a
RSN
1
1
×
×
COUT
C
IN
RSN
and C
IN
.
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