LTC6104
14
6104f
APPLICATIONS INFORMATION
decrease the response time, since VOUT = IOUT ROUT.
Reducing RIN and increasing ROUT will both have the
effect of increasing the voltage gain of the circuit.
Use of Dual Sense Resistors
The dual amplier topology offers signicant advantages
for controlling gain, dynamic range and shunt current.
As an example, separate shunt resistors can be advanta-
geous for an H-bridge current monitor (see H-Bridge Load
Current Monitor application). It can also be a signicant
advantage for battery-operated systems, where battery
discharge and charge current can be signicantly differ-
ent. With different current range requirements, a “charge
shunt resistor” can be connected from the charger to the
battery and a separate “discharge shunt resistor” can be
connected from the battery to the load. Other applications
can benet from similar topologies where different shunt
resistors enable the user to trade off accuracy and shunt
power consumption. Finally, since each amplier has an
independent input resistor, gain for each channel can be
set to suit the application. The only limitation to observe
in this type of application is that since the power for both
TYPICAL APPLICATION
H-Bridge Load Current Monitor
6104 TA02
VBATTERY
(8V TO 60V)
3V TO 18V
7
85
6
4
PWM*
249
2
4.99k
1
F
VO
10m
LT1790-2.5
4
6
2
1
PWM*
VO = 2.5V ±2V (±10A FS)
*USE “SIGN-MAGNITUDE” PWM FOR ACCURATE
LOAD CURRENT CONTROL AND MEASUREMENT
249
0.1
F
IM
LTC6104
sense ampliers is furnished via the +INB pin, the input
protection for both sections is referenced to this one pin.
Normal operation of section A is maintained for +INA
and –INA voltages within the range of 0.5V above +INB
to 1.5V below +INB. As long as both sense resistors are
connected to a common potential and voltage drops are
small (like <500mV, for example), as in Figure 8 or the
H-bridge application, this condition will be met.
Figure 8
VOUT
ROUT
VS
A
LTC6104
RINB
RINA
RSHUNTA
CURRENT
MIRROR
LOAD
BATTERY
B
6104 F08
VREF
RSHUNTB
CHARGER