MAX4372H Maxim, MAX4372H Datasheet - Page 6

• Manufacturer Part Number: MAX4372H
• Description: The MAX4372 low-cost, precision, high-side current-sense amplifier is available in a tiny, space-saving SOT23-5-pin package
• Manufacturer: Maxim

The MAX4372 high-side current-sense amplifier fea-
tures a 0 to 28V input common-mode range that is inde-
pendent of supply voltage. This feature allows the
monitoring of current flow out of a battery in deep dis-
charge, and also enables high-side current sensing at
voltages far in excess of the supply voltage (V
Current flows through the sense resistor, generating a
sense voltage (Figure 1). Since A1’s inverting input is
high impedance, the voltage on the negative terminal
equals V
match its negative terminal; therefore, the voltage
across R
current to flow through R
transistor and current mirror amplify the current by a
factor of β. This makes the current flowing out of the
current mirror equal to:
A2’s positive terminal presents high impedance, so this
current flows through R
R1 and R2 set the closed-loop gain for A2, which ampli-
fies V2+, yielding:
The gain of the device equals:
The MAX4372 operates over a wide variety of current
ranges with different sense resistors. Table 1 lists com-
mon resistor values for typical operation of the
MAX4372.
Low-Cost, UCSP/SOT23, Micropower, High-Side
Current-Sense Amplifier with Voltage Output
6
_______________Detailed Description
__________Applications Information
SOT23
_______________________________________________________________________________________
—
1
2
3
4
5
V
OUT
V
IN
G1
V
SENSE
PIN
Recommended Component Values
OUT
= R
- V
(V
V2+ = R
IN
SENSE
GD
2, 5, 7
SO
= R
3
4
1
8
6
- V1-) equals V
I
M
· · β · · V
GD
= β V
. A1 forces its positive terminal to
GD
GD
· · β (1 + R2 / R1) / R
SENSE
G1
β · · V
SENSE
, with the following result:
BUMP
UCSP
equal to V
A2
A3
A1
B1
B3
—
SENSE
/ R
/ R
SENSE
G1
G1
/ R
(1 + R2 / R1)
SENSE
NAME
. This creates a
G1
GND
OUT
RS+
N.C.
V
RS-
CC
G1
/ R
CC
G1
).
Ground
Output Voltage. V
(V
Supply Voltage. Use at least a 0.1µF capacitor to decouple V
transients.
Power Connection to the External Sense Resistor
Load-Side Connection to the External Sense Resistor
No Connection. Not internally connected.
. The
RS+
- V
RS-
Given the gain and maximum load current, select R
such that V
measure lower currents more accurately, use a high
value for R
voltage, which overcomes offset voltage errors of the
internal current amplifier.
In applications monitoring very high current, ensure
R
resistor’s rated power dissipation is exceeded, its value
may drift or it may fail altogether, causing a differential
voltage across the terminals in excess of the absolute
maximum ratings.
).
Figure 1. Functional Diagram
SENSE
2.7V
28V
TO
OUT
V
OUT
CC
is able to dissipate its own I
is proportional to the magnitude of V
SENSE
CURRENT
OUT
MIRROR
MAX4372T/F/H
does not exceed V
. A higher value develops a higher sense
FUNCTION
I
M
R2
Pin/Bump Description
A1
A2
V1+
V1-
V2+
V2-
100kΩ
100kΩ
R GD
R
R G1
R1
Choosing R
G2
CC
- 0.25V or 10V. To
GND
RS+
RS-
2
R losses. If the
SENSE
R
CC
SENSE
I
LOAD
0 TO 28V
from fast
LOAD
V
TO
IN
SENSE
V
SENSE
SENSE