LT1999MPMS8-10#TRPBF Linear Technology, LT1999MPMS8-10#TRPBF Datasheet - Page 19

• Manufacturer Part Number: LT1999MPMS8-10#TRPBF
• Description: SC-Amps/Current Sense, High Voltage, Bidirectional Current Sense Amplifier
• Manufacturer: Linear Technology

Specifications of LT1999MPMS8-10#TRPBF

• Input Bias Current: 137.5µA
• Output Current Per Channel: 26mA
• Input Offset Voltage: 1.5mV
• Bandwidth: 2MHz
• Cmrr: 120dB
• Slew Rate: 3V/µs
• Supply Voltage Range: 4.5V To 5.5V
• Supply Current: 3µA
• Rohs Compliant: Yes
• No. Of Amplifiers: 2

TYPICAL APPLICATIONS
Solenoid Current Monitor
The solenoid of Figure 7 consists of a coil of wire in an
iron case with permeable plunger that acts as a movable
element. When the MOSFET turns on, the diode is reversed
biased off, and current fl ows through R
the solenoid. If the MOSFET is turned off, the current
in the MOSFET is interrupted, but the energy stored in
the solenoid causes the diode to turn on and current to
freewheel in the loop consisting of the diode, R
the solenoid.
Figure 7 shows the LT1999 monitoring currents in a
ground referenced solenoid used when the coil is hard
tied to the case, and is tied to ground. Figure 8 shows a
supply referenced solenoid whose coil is insulated from
the case. The LT1999 will interface equally well to either
of these two confi gurations.
ON
OFF
V
S
SOLENOID
R
SENSE
0.1μF
V
V
+IN
–IN
5V
5V
4
1
2
3
V
V
V
Figure 7. Solenoid Current Monitor for Ground Tied Solenoid. The Common Mode
Inputs to the LT1999 Switch Between V
+
+
+
4k
4k
0.8k
0.8k
+
–
LT1999
SHDN
SENSE
to actuate
SENSE
–
+
V
R
V
+
G
+
160k
160k
2μA
1999 F07a
and
8
7
6
5
S
V
V
V
and One Diode Drop Below Ground
SHDN
OUT
REF
Bidirectional PWM Motor Monitor
Pulse width modulation is commonly used to effi ciently
vary the average voltage applied across a DC motor. The
H-bridge topology of Figure 9 allows full 4-quadrant control:
clockwise control, counter-clockwise control, clockwise
regeneration, and counter-clockwise regeneration. The
LT1999 in conjunction with a non-inductive current shunt
is used to monitor currents in the rotor. The LT1999 can
be used to detect stuck rotors, provide detection of over-
current conditions in general, or provide current mode
feedback control.
Figure 10 shows a plot of the output voltage of the
LT1999.
0.1μF
LT1999-10/LT1999-20/
SOLENOID PLUNGER PULLS IN
SOLENOID RELEASES
V
TIME (50ms/DIV)
OUT
V
+IN
LT1999-50
1999 F07b
19
2.5V
1999fa