LTC6102HV Linear Technology, LTC6102HV Datasheet - Page 13

• Manufacturer Part Number: LTC6102HV
• Description: Zero Drift High Side Current Sense Amplifier
• Manufacturer: Linear Technology

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APPLICATIONS INFORMATION
Useful Equations
Input Sense Range
The inputs of the LTC6102 can function from V
Not only does this allow a wide V
the input reference to be separate from the positive supply
(Figure 5). Note that the difference between V
must be no more than the input sense voltage range listed
in the Electrical Characteristics table.
Monitoring Voltages Above V
The LTC6102 may be confi gured to monitor voltages that are
higher than its supply, provided that the negative terminal
of the input voltage is within the input sense range of the
LTC6102. Figure 6 illustrates a circuit in which the LTC6102
Input Voltage: V
Current Gain:
Transconductance:
Transimpedance:
Voltage Gain:
Figure 5. V
R
SENSE
(V
+
– 2V) TO V
LOAD
V
BAT
+
Powered Separately from Load Supply (V
R
+
IN
+IN
V
I
V
SENSE
–
I
SENSE
V
SENSE
OUT
OUT
LTC6102
I
SENSE
V
OUT
V
+
=
I
SENSE
=
OUT
=
R
I
SENSE
R
SENSE
R
R
=
+
OUT
–
IN
IN
SENSE
R
and Level Translation
=
SENSE
R
•
1
IN
R
range, it also allows
SENSE
V
OUT
–INS
–INF
V
REG
6102 F05
+
•
R
R
OUT
+
R
IN
to (V
OUT
BAT
0.1μF
V
V
+
OUT
+
and V
BAT
– 2V).
)
+
has its supply pin tied to the lower potential terminal of the
sense resistor instead of the higher potential terminal. The
operation of the LTC6102 is such that the –INS and –INF
pins will servo to within a few microvolts of +IN, which is
shorted to V
includes V
across R
causing current V
the supply current of the LTC6102 is also monitored, as
it fl ows through R
Because the voltage across R
sense range of the LTC6102 in this circuit, V
large compared to the allowed sense voltage. This facilitates
the sensing of very large voltages, provided that R
chosen so that V
output current. The gain is still controlled by R
so either gain or attenuation may be applied to the input
signal as it is translated to the output. Finally, the input
may be a voltage source rather than a sense resistor, as
shown in Figure 7. This circuit allows the translation of
a wide variety of input signals across the entire supply
range of the LTC6102 with only a tiny offset error while
retaining simple gain control set by R
large voltages may be sensed as long as R
that I
example, V
large as 10V with R
a 5V maximum output, R
Figure 6. LTC6102 Supply Current Monitored with Load
OUT
R
SENSE
SENSE
does not exceed the allowed output current. For
LOAD
V
BAT
+
IN
, the circuit will operate properly. The voltage
+
. Since the input sense range of the LTC6102
may be as large as 1V with R
LTC6102/LTC6102HV
R
will be held across R
IN
SENSE
+IN
SENSE
SENSE
V
IN
–
= 10k. For a 10V maximum input and
LTC6102
/R
/R
.
IN
+
IN
IN
= 10k and R
does not exceed the allowed
to fl ow to R
SENSE
–
is not restricted to the
OUT
IN
V
OUT
OUT
–INS
–INF
V
REG
+
by the LTC6102,
OUT
/R
IN
IN
= 5k will allow
. In this case,
IN
SENSE
is chosen so
. Again, very
R
OUT
= 1k, or as
0.1μF
V
OUT
OUT
6102 F06
13
can be
/R
IN
6102f
IN
is
,