Datasheet
3
4
1
2
7
8
5
6
9
10
18
17
20
19
14
13
16
15
12
11
SDA
SCL
NC
VS
NC
EN
VREF
PROG
TIMER
GND
A0
A1
VINM
VINP
GND
VCC
SENSE
GATE
OUT
PG
C
T
R
PROG1
R
PROG2
R
SDA
10kW
R
SDA
10kW
C
VS
0.1mF
C
EN
0.1mF
R
EN2
SDA
SCL
3P3V_USB
R
EN1
VCC
R
S
R
G
D1
VCC VOUT
C
O
1kW
C
G
R
PG
C
1
0.1mF
A0
A1
Optional :
Use with dV/dt control
TPS2480/1
I2C
Addresses
+
R
B
D2
5.1V
C2
0.1mF
C
VIN
R
MB
R
IN
R
MA
M1
VIN
9V to 57V
TPS2480
TPS2481
www.ti.com
SLUS939B –APRIL 2010–REVISED DECEMBER 2010
High Voltage Application Example
The TPS2480/81 can be used to monitor current from a voltage source greater than 26 V by using the OPAMP
circuit shown in Figure 19.
Figure 19. TPS2480/81 High Voltage Application
The basic operating principle of U2, Q1, R
MA
, and R
MB
is to mirror the voltage seen across R
S
from a VCC
referenced voltage to a GND referenced voltage. As load current flows through R
S
, the voltage input to U2-3
decreases and the output of U2/Q1 as seen at Q1-S follows this sense voltage. Ideally, the voltage drop across
R
MA
mirrors the voltage drop across R
S
. Current flow through R
MB
will mirror current flow through R
MA
, and if
R
MA
= R
MB
then the sense voltage across R
S
is mirrored at VINP.
Since only a small voltage will be across R
MA
and R
MB
, their nominal value should be fairly low to offset input
bias current effects (I
VINP
). TPS2480/1 input bias current sums with the current that flows through R
MA
increasing
the voltage drop across R
MB
. To block the bias current from R
MB
, an additional buffer may be inserted between
Q1-D and VINP. Using a network type resistor for R
MA
and R
MB
designed with temperature coefficient tracking
will provide good voltage mirroring.
U2 should be a high quality, low drift operational amplifier. The OPA333AID provides low input voltage offset and
very low drift over time and temperature. U2 is referenced to VCC through D2 and R
B
and can operate from rail
to rail.
Copyright © 2010, Texas Instruments Incorporated Submit Documentation Feedback 25
Product Folder Link(s): TPS2480 TPS2481