LMP8358

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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

1

μA 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:

(2)

Table 12. Filter (Register bit 10)

FILT

Mode

0

No external filter cap used

1

External filter cap used

Gain

10

18.5 k

Ω

20

112 k

Ω

50

168 k

Ω

100

187 k

Ω

200

1.12 M

Ω

500

1.68 M

Ω

1000

1.87 M

Ω

User-Defined Gain

External Resistor R1

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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