Datasheet
.01 .1 1 10
.001
.01
.1
1
10
VCC - VOUT (V)
SOURCING CURRENT (mA)
V
CC
= 12V
-40°C
+25°C
+85°C
+125°C
.01 .1 1 10
.001
.01
.1
1
10
VOUT (V)
SINKING CURRENT (mA)
V
CC
= 12V
-40°C
+25°C
+85°C
+125°C
.01 .1 1 10
.001
.01
.1
1
10
VOUT (V)
SINKING CURRENT (mA)
V
CC
= 5V
-40°C
+25°C
+85°C
+125°C
.01 .1 1 10
.001
.01
.1
1
10
VCC - VOUT (V)
SOURCING CURRENT (mA)
V
CC
= 5V
-40°C
+25°C
+85°C
+125°C
LMP8480, LMP8481
SNVS829A –JUNE 2012–REVISED AUGUST 2012
www.ti.com
Typical Performance Characteristics (continued)
Unless otherwise specified, T
A
= 25°C, V
CC
= 4.5V to 76V, 4.5V < V
CM
< 76V, R
L
= 100k, V
SENSE
= (V
R
SP
– V
R
SN
) = 0V, for all
gain options.
Saturated Output Sourcing Current at 4.5V Saturated Output Sinking Current at 4.5V
Saturated Output Sourcing Current at 12V Saturated Output Current Sinking at 12V
Application Information
LMP8480 AND LMP8481 INTRODUCTION
The LMP8480 and LMP8481 are single supply, high side current sense amplifiers with available fixed gains of
x20, x50, x60 and x100. The power supply range is 4.5V to 76V, while the common mode input voltage range is
capable of 4.0V to 76V operation. The supply voltage and common mode range are completely independent of
each other. This makes the LMP848x supply voltage extremely flexible, as the LMP848x's supply voltage can be
greater than, equal to, or less than the load source voltage, and allowing the device to be powered from the
system supply or the load supply voltage.
The amplifier supply voltage does not have to be larger than the load source voltage. A 76V load source voltage
with a 5V LMP8481 supply voltage is perfectly acceptable.
THEORY OF OPERATION
The LMP8480 and LMP8481 are comprised of two main stages. The first stage is a differential input current to
voltage converter, followed by a differential voltage amplifier and level-shifting output stage. Also present is an
internal 14 Volt Low Dropout Regulator (LDO) to power the amplifiers and output stage, as well as a reference
divider resistor string to allow the setting of the reference level.
As seen in Figure 7, the current flowing through R
SENSE
develops a voltage drop called V
SENSE
. The voltage
across the sense resistor, V
SENSE
, is then applied to the input R
SP
and R
SN
pins of the amplifier.
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