Datasheet

LMP8358
www.ti.com SNOSB09B –APRIL 2010–REVISED MARCH 2013
Shutdown Enable (Serial, Parallel)
When the SHDN bit of the LMP8358 register is set to 1b the part is put into shutdown mode. It will use less than
1μA in this state.
Table 11. Shutdown (Register bit 9)
SHDN Mode
0 Active mode
1 Shutdown mode
Filter and External Filter Capacitor (Serial)
The FILT bit controls the state of switch S2 shown in the Block Diagram. When G[2:0] = 000b to 110b, switch S2
will be open if FILT = 0b and S2 will be closed if FILT = 1b. When G[2:0] = 111b switch S2 is always closed and
does not depend on the value in the FILT bit.
When FILT = 1b and COMP[2:0] = 1xxb the LMP8358 is unity-gain stable and an external filter cap can be
applied as shown in Figure 53. The corner filter of the filter is:
F
-3dB
= 1/(2πR
FILTER
C
FILTER
) (2)
R
FILTER
depends on the gain of the part and is shown inTable 13.
Table 12. Filter (Register bit 10)
FILT Mode
0 No external filter cap used
1 External filter cap used
Table 13. R
FILTER
Value
Gain R
FILTER
Value
10 18.5 kΩ
20 112 kΩ
50 168 kΩ
100 187 kΩ
200 1.12 MΩ
500 1.68 MΩ
1000 1.87 MΩ
User-Defined Gain External Resistor R1
The tolerance of the R
FILTER
value for the pre-defined gains is about ±3%. If an external filter cap is not used
FILT should be set to 0b to prevent errors related to leakage currents on the FB pin.
Fault Detection Pin and Current Setting (Serial)
The LMP8358 has an internal current source that can be used to detect faults in the overall system. See the
FAULT DETECTION METHODS Section. When PIN = 0b this current source is connected to the +IN pin. When
PIN = 1b the current source is connected to the −IN pin.
Table 14. Pin Current Source (Register bit 11)
PIN Current source is connected to
0 +IN pin
1 −IN pin
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