MCP2021 datasheet(10/46 Pages) MICROCHIP

10 / 46 page

MCP2021/2

DS22018E-page 10

1.6

Internal Voltage Regulator

1.6.1

5.0V REGULATOR

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

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

50 mA of load current over the entire operating

temperature 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 typically +0.5V (+1V maximum over the

full operating temperature 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 capac-

ity 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 shutdown protection built-in.

Regarding the correlation between VBB, VREG and IDD,

please refer to Figure 1-5 through 1-7. 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 Power-on Reset trip point. The MCP2021 will then

monitor VBB and turn on the regulator when Vbb is

6.0V.

When the input voltage (VBB) drops below the

differential 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

Power-on Reset trip point. The regulator output will

stay off until VBB is above +5.75 VDC.

In the start phase, the device must see at least 6.0V 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

over

temperature

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 1-4:

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) then the VREG will be switched back

on.

Pass

Element

Sampling

Network

Buffer

VREG

VBB

VSS

Fast

Transient

Loop

VREF

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