LT1999MPMS8-50#TRPBF Linear Technology, LT1999MPMS8-50#TRPBF Datasheet - Page 18

• Manufacturer Part Number: LT1999MPMS8-50#TRPBF
• Description: SC-Amps/Current Sense, High Voltage, Bidirectional Current Sense Amplifier
• Manufacturer: Linear Technology

Specifications of LT1999MPMS8-50#TRPBF

• Input Bias Current: 137.5µA
• Output Current Per Channel: 26mA
• Input Offset Voltage: 1.5mV
• Bandwidth: 1.2MHz
• Cmrr: 120dB
• Slew Rate: 3V/µs
• Supply Voltage Range: 4.5V To 5.5V
• Supply Current: 3µA
• Rohs Compliant: Yes
• No. Of Amplifiers: 2

LT1999-10/LT1999-20/
LT1999-50
APPLICATIONS INFORMATION
Fuse Monitor
The inputs can be overdriven without fear of damaging
the LT1999. This makes the LT1999 ideal for monitoring
fuses if either +IN or –IN are shorted to ground while the
other is at the full common mode supply voltage (see
Figure 5). If the fuse in Figure 5 opens with the +IN tied
to the positive supply, the load will pull –IN to GND. The
output will be forced to the positive V
desired that the output be near ground if the fuse opens,
it is a simple matter of swapping the inputs. Precautions
should be followed: First, when the inputs are stressed
differentially due to the fuse blowing open, a large voltage
drop will be placed across the +IN to –IN pins, dissipating
18
ON
LOAD
OFF
Figure 6. A Plot of the LT1999’s Output Voltage vs V
In Applications Where the Sense Voltage Is Driven in Excess of –25V, the Output
of the LT1999 Will Undergo Phase Reversal
V
S
V
V
V
STEERING
DIODE
SHDN
OUT
REF
I
LOAD
R
FUSE
5V
+
SENSE
V
V
5V
+IN
–IN
supply rail. If it is
Figure 5. Using the LT1999 to Monitor a Fuse
0.1μF
4
1
2
3
–60
V
V
V
V
V
+
REF
OUT
+
+
–45
4k
4k
= 2.5V
PHASE REVERSAL FOR V
–30
0.8k
0.8k
–15
V
SENSE
+
–
LT1999
0
(V)
power in the precision on-chip input resistors. Precaution
should be taken to prevent junction temperatures from
exceeding the Absolute Maximum ratings (see Note 3 in the
Electrical Characteristics section). Secondly, if the load is
inductive, and the fuse blows open without a clamp diode,
energy stored in the inductive load will be dissipated in
the LT1999, which could cause damage. A simple steering
diode as shown in Figure 5 will prevent this from happen-
ing, and will protect the LT1999 from damage.
Finally, the user should be aware that in fuse monitoring
applications with the sense voltage (V
being driven in excess of –25V, the output of the LT1999
will undergo phase reversal (see Figure 6).
SHDN
15
SENSE
30
< –25V
45
–
+
SENSE
V
R
1999 F06
V
+
G
+
160k
160k
60
2μA
1999 F05
(V
SENSE
8
7
6
5
V
V
V
SHDN
OUT
REF
= V
0.1μF
+IN
– V
– IN
).
SENSE
= V
+ IN
– V
1999fa
– IN
)