Datasheet

LMP8358
SNOSB09B –APRIL 2010–REVISED MARCH 2013 www.ti.com
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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