MCP1710 datasheet(13/24 Pages) MICROCHIP

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DS20005158D-page 13

MCP1710

4.0

DEVICE OVERVIEW

The MCP1710 is a 100 mA/200 mA output current, Low

Dropout (LDO) voltage regulator. The Low Dropout

voltage of 450 mV maximum, at 200 mA of current,

makes it ideal for battery-powered applications. The input

voltage ranges from 2.5V to 5.5V. The MCP1710 adds a

shutdown control input pin. The MCP1710 is available in

eight standard fixed output voltage options: 1.2V, 1.5V,

1.8V, 2V, 2.5V, 3.0V, 3.3V and 4.2V. The MCP1710 uses

a proprietary voltage reference and sensing scheme to

maintain the ultra low 20 nA quiescent current.

4.1

Output Current and Current

Limiting

The MCP1710 LDO is tested and ensured to supply a

minimum of 200 mA of output current for the 1.2V to

3.5V output range, and 100 mA of output current for the

3.5V to 4.2V output range. The MCP1710 has no

minimum output load, so the output load current can go

to 0 mA and the LDO will continue to regulate the

output voltage within the specified tolerance.

The MCP1710 also incorporates an output current limit.

The current limit is set to 250 mA, typical, for the

1.2V

 VR ≤3.5V range, and 175 mA, typical, for the

3.5V

 VR  5.5V range.

4.2

Output Capacitor

The MCP1710 requires a minimum output capacitance

of 1 µF for output voltage stability. Ceramic capacitors

are recommended because of their size, cost and

robust environmental qualities.

Aluminum-electrolytic and tantalum capacitors can be

used on the LDO output as well. The output capacitor

should be located as close to the LDO output as is

practical. Ceramic materials, X7R and X5R, have

low-temperature coefficients and are well within the

acceptable ESR range required. A typical 1 µF X7R

0805 capacitor has an ESR of 50 m

.

4.3

Input Capacitor

Low input source impedance is necessary for the LDO

output to operate properly. When operating from batteries,

or in applications with long lead length (>10 inches)

between the input source and the LDO, some input

capacitance is recommended. A minimum of 1.0 µF to

4.7 µF is recommended for most applications.

For applications that have output step load require-

ments, the input capacitance of the LDO is very

important. The input capacitance provides a

low-impedance source of current for the LDO to use for

dynamic load changes. This allows the LDO to respond

quickly to the output load step. For good step response

performance, the input capacitor should be of equiva-

lent or higher value than the output capacitor. The

capacitor should be placed as close to the input of the

LDO as is practical. Larger input capacitors will also

help reduce any high-frequency noise on the input and

output of the LDO, as well as the effects of any

inductance that exists between the input source

voltage and the input capacitance of the LDO.

4.4

Shutdown Input (SHDN)

The SHDN input is an active-low input signal that turns

the LDO on and off. The SHDN threshold is a

percentage of the input voltage. The maximum input

low logic level is 30% of VIN and the minimum high logic

level is 70% of VIN.

On the rising edge of the SHDN input, the shutdown

circuitry has a 30 ms (typical) delay before allowing the

LDO output to turn on. This delay helps to reject any

false turn-on signal or noise on the SHDN input signal.

After the 30 ms delay, the LDO output enters its

current-limited soft start period as it rises from 0V to its

final regulation value. If the SHDN input signal is pulled

low during the 30 ms delay period, the timer will be

reset and the delay time will start over again on the next

rising edge of the SHDN input. The total time from the

SHDN input going high (turn on) to the LDO output

being in regulation is typically 30 ms. See Figure 4-1 for

a timing diagram of the SHDN input.

FIGURE 4-1:

Shutdown Input Timing

Diagram.

4.5

Dropout Voltage

Dropout voltage is defined as the input-to-output voltage

differential at which the output voltage drops 3% below

the nominal value that was measured with a VR + 0.8V

differential applied. The MCP1710 LDO has a Low

Dropout voltage specification of 450 mV for the

1.2V

 VR ≤ 3.5V range (typical) at 200 mA out, and

400 mV for the 3.5V

 VR  5.5V range (typical) at

100 mA

out.

See

Section 1.0

“Electrical

Characteristics” for maximum dropout voltage

specifications.

SHDN

VOUT

30 ms

10 µs

TOR

20 ns (typical)

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