LTC6104 LINER [Linear Technology], LTC6104 Datasheet - Page 7

• Manufacturer Part Number: LTC6104
• Description: High Voltage, High Side, Bi-Directional Current Sense Amplifi er
• Manufacturer: LINER [Linear Technology]

BLOCK DIAGRAM
THEORY OF OPERATION
When V
forces –INA to have the same potential as +INA. Connect-
ing an external resistor, R
a current, V
impedance inputs of the sense amplifi er will not conduct
this input current, so the current will fl ow through an
internal MOSFET to the OUT pin.
The output current can be transformed into a voltage by
adding a resistor from OUT to a reference voltage (V
output voltage is then V
When operating on a dual supply, R
The output voltage is then V
Only one amplifi er is active at a time in the LTC6104. If the
load current direction (V
SENSE
SENSE
is positive, an internal sense amplifi er loop
/R
INA
OUT
, to fl ow through R
SENSE
INA
OUT
= (V
, in series with –INA causes
V
OUT
= (V
SENSE
is negative) activates the
V
–
= V
OUT
SENSE
SENSE
+
8
+INA
5k
can be tied to ground.
/R
A
INA
•
10V
R
/R
R
OUT
7
–
IN
V
) • R
–INA
R
5k
OUT
INA
INA
INB
V
+ V
Figure 1. LTC6104 Block Diagram
+
) • R
REF
OUT
. The high
REF
+
–
1
OUT
+ V
OUT
R
). The
V
OUT
.
REF
REF
10V
–
R
V
.
SENSE
SENSE
“B” amplifi er, the “A” amplifi er will be inactive. The signal
current goes into the –INB pin, through the MOSFET, and
into the current mirror. The mirror reverses the polarity of
the signal so that current fl ows into the “OUT” pin, causing
the output voltage to change polarity. The magnitude of the
output is then V
that the OUT voltage cannot swing below V
it’s sinking current. A proper V
chosen so that the designed OUT voltage swing does not
go beyond the specifi ed voltage range of the output.
Supply current is drawn from +INB pin. The user may
choose to include this current in the monitored current
through R
V
+
S
10V
4
V
SENSE
–
I
V
LOAD
+
–
6
SENSE
–INB
by careful choice of connection polarity.
R
5k
INA
B
+
5
• R
+INB
5k
6104 F01
V
OUT
–
/R
INB
REF
+ V
and R
REF
LTC6104
OUT
. Keep in mind
–
, even though
need to be
7
6104f