ltc4151 Linear Technology Corporation, ltc4151 Datasheet - Page 8

• Manufacturer Part Number: ltc4151
• Description: High Voltage I2c Current And Voltage Monitor
• Manufacturer: Linear Technology Corporation

APPLICATIONS INFORMATION
LTC4151/LTC4151-1
The LTC4151/LTC4151-1 offer a compact complete solu-
tion for high side power monitoring. With a wide operating
voltage range from 7V to 80V, these devices are ideal for
a variety of applications including consumer, automotive,
industrial and telecom infrastructure. The simple applica-
tion circuit as shown in Figure 1 provides monitoring of
high side current with a 0.02Ω resistor (4.096A in full-
scale), input voltage (102.4V in full-scale) and an external
voltage (2.048V in full-scale), all with an internal 12-bit
resolution ADC.
Data Converter
The LTC4151/LTC4151-1 feature an onboard, 12-bit analog-
to-digital converter (ADC) that continuously monitors three
voltages in the sequence of (V
second and V
SENSE
scale and 20μV resolution that allows accurate measure-
ment of the high side input current. The supply voltage
at V
25mV resolution. The voltage at the uncommitted ADIN
pin is measured with a 2.048V full-scale and 0.5mV reso-
lution that allows monitoring of any external voltage. The
12-bit digital code of each measured voltage is stored in
8
IN
is directly measured with a 102.4V full-scale and
+
and SENSE
ADIN
third. The differential voltage between
–
is monitored with an 81.92mV full-
V
IN
Figure 1. Monitoring High Side Current and Voltages Using the LTC4151
SENSE +
2
3
4
– V
V
ADR1
ADR0
IN
SENSE –
SENSE
1
+
) fi rst, V
LTC4151
0.02Ω
GND
9
SENSE
IN
10
SHDN
ADIN
–
SDA
SCL
8
6
7
5
two adjacent registers out of the six total data registers
A through F , with the eight MSBs in the fi rst register and
the four LSBs in the second (Table 2).
The data in registers A through F is refreshed at a frequency
of 7.5Hz in continuous scan mode. Setting control register
bit G4 (Table 6) invokes a test mode that halts updating
of these registers so that they can be written to and read
from for software testing.
The data converter features a snapshot mode allowing us-
ers to make one-time measurements of a selected voltage
(either the SENSE voltage, V
To enable snapshot mode, set control register bit G7 and
write the two-bit code of the desired ADC channel to G6
and G5 (Table 6) using a Write Byte command. When the
Write Byte command is completed, the ADC measures the
selected voltage and a Busy Bit in the LSB data register
is set to indicate that the data is not ready. After complet-
ing the conversion, the ADC is halted and the Busy Bit is
reset to indicate that the data is ready. To make another
measurement of the same voltage or to measure another
voltage, fi rst disable the snapshot mode for the previous
measurement by clearing control bit G7, then re-enable the
snapshot mode and write the code of the desired voltage
according to the procedure described above.
V
OUT
V
ADIN
2k
2k
SCL
SDA
μ-Controller
3.3V
V
IN
41511 F01
DD
voltage, or ADIN voltage).
41511f