LTC6103
13
6103f
APPLICATIONS INFORMATION
Voltage Translator
Each amplifi er of the LTC6103 can be used as a high volt-
age level translator circuit as shown in Figure 7. In this
application, the LTC6103 translates a differential voltage
signal riding on top of a high common mode voltage. V
IN
signals get converted to a current, through R
IN
, and then
scaled down to a ground referenced voltage across R
OUT
.
Since the V
SUPPLY
must be at least 4V and the maximum
input voltage is 70V, this circuit can translate differential
signals with up to 66V of variation in V
TRANSLATE
.
With the dual LTC6103, half of the device can be used
to monitor a high side referenced signal and the other
amplifi er can be used for current sensing.
Output Connection Methods
The outputs of the LTC6103 are current sources and may
be connected to subsequent circuitry in several ways.
As a dual current sense part, each output can be used
independently and in differing ways if desired.
For applications where the destination is local to the
device, R
OUT
resistors may be co-located with the part to
form voltage sources. It is also possible to remotely locate
the R
OUT
resistors so that the current generated output
voltage drop is developed against a different ground refer-
ence point than the LTC6103 V
–
, such as at an ADC within
another assembly. This method provides the elimination
of ground drop errors from effecting the measurement.
Ground differentials that are small enough to prevent
conduction of the output protection zener (>8V positive
or a couple hundred mV negative) can be rejected without
affecting linearity.
In the Typical Application, “±10A Differential Output Bidi-
rectional Monitor,” the outputs are kept separate, but are
treated as a differential pair. This connection allows placing
R
OUT
resistors local to the LTC6103, and yet ground drop
errors are rejected a the destination circuit as common
mode voltage shift, not signal error. This connection is
also shown in the application, ±10A Bidirectional H-Bridge
Monitor.
The outputs can also be tied together to drive a single
R
OUT
as in the Typical Application, 5A Absolute Value
Bidirectional Monitor, producing an additive function. In
that particular circuit the two inputs are wired oppositely
form the same sense resistor, so the resulting output is
an absolute value signal.
+
–
V
S
1/2
LTC6103
R
IN
V
IN
+–
R
OUT
V
OUT
6103 F07
V
TRANSLATE
Figure 7. Operation as Voltage Translator
