internal reference. Increasing the area will decrease the

chance of fitting the die into a smaller package. Increasing

the current drawn by the internal reference increases the

total supply current (ground pin current). Using an optimized

trade-off of ground pin current and die size, LP3962EP/

LP3965EP achieves low noise performance and low quies-

cent current operation.

The

total

output

noise

specification

for

LP3962EP/

LP3965EP is presented in the Electrical Characteristics

table. The Output noise density at different frequencies is

represented by a curve under typical performance charac-

teristics.

SHORT-CIRCUIT PROTECTION

The LP3962and LP3965 is short circuit protected and in the

event of a peak over-current condition, the short-circuit con-

trol loop will rapidly drive the output PMOS pass element off.

Once the power pass element shuts down, the control loop

will rapidly cycle the output on and off until the average

power dissipation causes the thermal shutdown circuit to

respond to servo the on/off cycling to a lower frequency.

Please refer to the section on thermal information for power

dissipation calculations.

ERROR FLAG OPERATION

The LP3962EP/LP3965EP produces a logic low signal at the

Error Flag pin when the output drops out of regulation due to

low input voltage, current limiting, or thermal limiting. This

flag has a built in hysteresis. The timing diagram in Figure 1

shows the relationship between the ERROR and the output

voltage. In this example, the input voltage is changed to

demonstrate the functionality of the Error Flag.

The internal Error flag comparator has an open drain output

stage. Hence, the ERROR pin should be pulled high through

a pull up resistor. Although the ERROR pin can sink current

of 1mA, this current is energy drain from the input supply.

Hence, the value of the pull up resistor should be in the

range of 10k

Ω to 1MΩ. The ERROR pin must be con-

nected to ground if this function is not used. It should

also be noted that when the shutdown pin is pulled low, the

ERROR pin is forced to be invalid for reasons of saving

power in shutdown mode.

SENSE PIN

In applications where the regulator output is not very close to

the load, LP3965EP can provide better remote load regula-

tion using the SENSE pin. Figure 2 depicts the advantage of

the SENSE option. LP3962EP regulates the voltage at the

output pin. Hence, the voltage at the remote load will be the

regulator output voltage minus the drop across the trace

resistance. For example, in the case of a 3.3V output, if the

trace resistance is 100m

Ω, the voltage at the remote load

will be 3.15V with 1.5 A of load current, I

The

LP3965EP regulates the voltage at the sense pin. Connect-

ing the sense pin to the remote load will provide regulation at

the remote load, as shown in Figure 2. If the sense option pin

is not required, the sense pin must be connected to the V

OUT

pin.

20114707

FIGURE 1. Error Flag Operation

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