MCP2021 datasheet(16/52 Pages) MICROCHIP

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MCP2021/2/1P/2P

DS22018F-page 16

1.6

Internal Voltage Regulator

1.6.1

5.0V REGULATOR

The MCP2021 has a low-drop-out voltage, positive reg-

ulator capable of supplying 5.00 VDC ±3% at up to

50 mA of load current over the entire operating temper-

ature range of -40°C to +125°C. With a load current of

50 mA, the minimum input to output voltage differential

required for the output to remain in regulation is typi-

cally +0.5V (+1V maximum over the full operating tem-

perature range). Quiescent current is less than 100 µA

with a full 50 mA load current when the input to output

voltage differential is greater than +3.00V.

The regulator requires an external output bypass

capacitor for stability. See Figure 2-3 for correct

capacity and ESR for stable operation.

Designed for automotive applications, the regulator will

protect itself from double-battery jumps and up to +43V

load dump transients. The voltage regulator has both

short-circuit and thermal-shut-down protection built in.

Regarding the correlation between VBB, VREG and IDD,

please refer to Figure 1-10 throughFigure 1-12. When

the input voltage (VBB) drops below the differential

needed to provide stable regulation, the output VREG

will track the input down to approximately 3.5V, at

which point the regulator will turn off. This will allow

microcontrollers with internal POR circuits to generate

a clean arming of the POR trip point. The MCP2021 will

then monitor VBB and turn on the regulator when VBB

rises above 5.75, again.

When the input voltage (VBB) drops below the differen-

tial needed to provide stable regulation, the output

VREG) will track the input down to approximately

+4.25V. The regulator will turn off the output at this

point. This will allow PIC® microcontrollers with internal

POR circuits to generate a clean arming of the POR trip

point. The regulator output will stay off until VBB is

above +5.75 VDC.

In the start phase, the device must detect at least 5.75V

to initiate operation during power up. In the Power-

Down mode, the VBB monitor will be turned off.

The regulator has a thermal shutdown. If the thermal

protection circuit detects an overtemperature condition,

and the signals TXD and RXD are LOW, or TXD is HIGH,

the regulator will shut down. The recovery from the

thermal shutdown is equal to adequate cooling time.

FIGURE 1-9:

Voltage Regulator Block Diagram.

Note:

The regulator has an overload current

limiting of approximately 100 mA. During a

short circuit, the VREG is monitored. If

VREG is lower than 3.5V, the VREG will turn

off. After a recovery time of about three

milliseconds, the VREG will be checked

again. If there is no short circuit (VREG

>3.5V), the VREG will be switched back on.

Pass

Element

Sampling

Network

Buffer

VREG

VBB

VSS

Fast

Transient

Loop

VREF

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