LMP8358

SNOSB09B – APRIL 2010 – REVISED MARCH 2013

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Table 3. Function of Digital IO Pins, Serial Mode

Pin Name

Description

SDO

Serial Data Out

SDI

Serial Data In

SCK

Serial Clock

CSB

Chip Select

VLSER

Negative Logic level

VHSER

Positive Logic Level

Table 4. LMP8358 Register Description, Serial Mode

Bit No

Name

Description

0

G0

Gain setting (LSB)

1

G1

Gain setting

2

G2

Gain setting (MSB)

3

COMP0

Frequency compensation setting (LSB)

4

COMP1

Frequency compensation setting

5

COMP2

Frequency compensation setting (MSB)

6

MUX0

Input multiplexer selection (LSB)

7

MUX1

Input multiplexer selection (MSB)

8

POL

Input polarity switch

9

SHDN

Shutdown Enable

10

FILT

Enable filtering using external cap

11

PIN

Fault detection pin selection

12

CUR0

Fault detection current setting (LSB)

13

CUR1

Fault detection current setting

14

CUR2

Fault detection current setting (MSB)

15

N/A

Unused, set to 0

Serial Control Interface Operation

The LMP8358 gain, bandwidth compensation, shutdown, input options, and fault detection are controlled by an

on board programmable register. Data to be written into the control register is first loaded into the LMP8358 via

the serial interface. The serial interface employs an 16-bit double-buffered register for glitch-free transitions

between settings. Data is loaded through the serial data input, SDI. Data passing through the shift register is

output through the serial data output, SDO. The serial clock, SCK controls the serial loading process. All sixteen

data bits are required to correctly program the amplifier. The falling edge of CSB enables the shift register to

receive data. The SCK signal must be high during the falling and rising edge of CSB. Each data bit is clocked

into the shift register on the rising edge of SCK. Data is transferred from the shift register to the holding register

on the rising edge of CSB. Operation is shown in the SPI Timing Diagram.

The serial control pins can be connected in one of two ways when two or more LMP8358s are used in an

application.

Star Configuration

The configuration shown in Figure 50 can be used if each LMP8358 will always have the same value in each

register. After the microcontroller writes, all registers will have the same value. Using multiple CSB lines as

shown in Figure 51 allows different values to be written into each register.

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