LTC4151/LTC4151-1

8

41511fa

APPLICATIONS INFORMATION

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 0.02

Ω 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

scale and 20μV resolution that allows accurate measure-

(see Figure 10) for proper ADC readout. The supply volt-

and 25mV resolution. The voltage at the uncommitted

ADIN pin is measured with a 2.048V full-scale and 0.5mV

resolution that allows monitoring of any external voltage.

Figure 1. Monitoring High Side Current and Voltages Using the LTC4151

The 12-bit digital code of each measured voltage is stored

in two adjacent registers out of the six total data registers

A through F, with the eight MSBs in the first 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

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, first 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.

41511 F01

0.02Ω

μ-Controller

LTC4151

SHDN

7V TO 80V

2

3

4

SCL

SDA

ADIN

ADR1

SCL

8

110

6

7

5

9

SDA

ADR0

GND

3.3V

2k

2k