DatasheetQ Logo
Electronic component search and free download site. Transistors,MosFET ,Diode,Integrated circuits

MAX9643(2011) 查看數據表(PDF) - Maxim Integrated

零件编号
产品描述 (功能)
生产厂家
MAX9643
(Rev.:2011)
MaximIC
Maxim Integrated MaximIC
MAX9643 Datasheet PDF : 12 Pages
1 2 3 4 5 6 7 8 9 10 Next Last
MAX9643
60V High-Speed Precision Current-Sense Amplifier
Detailed Description
The MAX9643 is a high-speed precision current-sense
amplifier ideal for a wide variety of high-performance
industrial and automotive power-supply applications. The
device’s low input offset voltage, tight gain error, and low
temperature drift characteristics allow the use of small-
sense resistors for current measurements to improve
power-supply conversion efficiency and accuracy of mea-
surements. Its fast response allows it to react quickly to
switching currents as is common in power-supply circuits,
and makes it possible to be used as part of control loops.
The unidirectional high-side, current-sense amplifier
also features a wide -1.5V to +60V input common-mode
range. This feature allows monitoring of power-supply
load current even if the rail is shorted to ground. High-
side current monitoring does not interfere with the ground
path of the load being measured, making the IC particu-
larly useful in a wide range of high-reliability systems.
The IC has been designed on a proprietary high-speed
complementary BiCMOS SOI process. This high-voltage
analog process is optimized for excellent AC dynamic
performance, ultra-low noise, wide operating voltage
range, and low-drift signal conditioning circuitry.
Application Information
Internal Charge Pump
An internal charge pump on the part is utilized to provide
two attractive application features:
U Input common-mode voltage range extends to 1.5V
below ground.
U Output voltage range extends down to true ground.
A 250kHz internal charge pump is used to generate a
negative voltage rail to bias both the input stage and
output stage of the current-sense amplifier. Use a 1FF
ceramic capacitor between the CP1 and CP2 pins of the
IC, and ensure a tight layout to minimize loop area. Using
a 1FF ceramic capacitor from VEE to GND is essential to
good low-noise performance.
It is possible to also connect the VEE pin directly to an
external -5V power supply. Ensure that this voltage is
lower than the internally generated charge-pump voltage.
The MAX9643 EV kit shows a good example layout. A
representation is shown in Figure 1.
Input Common-Mode Voltage Range
The use of an internal negative voltage rail for its
input stage allows the current-sense amplifier to extend
its input common-mode voltage below ground without
any crossover inaccuracies. Crossover problems with
precision can occur with alternate architectures of
current-sense amplifiers that use two different input
differential stages to cover the entire operating common-
mode voltage range (either npn/pnp transistors or pnp
transistor and resistor-based input stages).
The minimum input common-mode voltage capability
is dependent on the internal negative voltage rail gener-
ated by the charge pump. Since this negative voltage rail
goes down at low values of VCC (i.e., when under 5V), the
minimum input common-mode voltage rail is also limited
at low VCC.
The negative input common-mode voltage specification
can be exceeded if the input current is limited to under
5mA. This is typically accomplished by using series
input resistors. The input ESD structure for negative input
common-mode voltages looks like 5 series-connected
diodes. Assuming an on-drop of 0.7V per diode, negative
TO ADC
FROM RSENSE
8765
MAX9643
+
1 234
1µF
1µF
0.1µF
Figure 1. PCB Layout
����������������������������������������������������������������� Maxim Integrated Products  8

Share Link: 

datasheetq.com  [ Privacy Policy ]Request Datasheet ] [ Contact Us ]