MCP2021-500ESLASHP datasheet(6/54 Pages) MICROCHIP

6 / 54 page

MCP2021/2/1P/2P

DS20002018H-page 6

 2005-2014 Microchip Technology Inc.

FIGURE 1-1:

THERMAL SHUTDOWN STATE DIAGRAMS

1.3

Modes of Operation

For an overview of all operational modes, please refer

to Table 1-1.

1.3.1

POWER-ON RESET MODE

Upon application of VBB, the device enters Power-On

Reset mode (POR). During this mode, the part main-

tains the digital section in a Reset mode and waits until

the voltage on pin VBB rises above the “ON” threshold

(typically 5.75V) to enter to the Ready mode. If during

the operation, the voltage on pin VBB falls below the

“OFF” threshold (typically 4.25V), the part comes back

to the POR mode.

1.3.2

POWER-DOWN MODE

In Power-Down mode, the transmitter and the voltage

regulator are off. Only the receiver wake-up from the

LIN bus section, and the CS/LWAKE pin wake-up

circuits, are in operation. This is the lowest power

mode.

If pin CS/LWAKE goes to a high level during

Power-Down mode, the device immediately enters

Ready mode and enables the voltage regulator; and

after the output has stabilized (approximately 0.3 ms to

1.2 ms), the device goes to Operation mode or Trans-

mitter-Off mode (see Figure 1-2 for MCP2021/2 and

Figure 1-4 for MCP2021P/2P).

LIN bus activity will also change the device from

Power-Down mode to Ready mode. MCP2021/2

wakes up on the dominant level of the LIN bus, and

MCP2021P/2P on a falling edge that follows a domi-

nant level lasting 20 µs of time.

The Power-Down mode can be reached through either

Operation mode or Transmitter-Off mode.

1.3.3

READY MODE

Upon entering Ready mode, the voltage regulator and

receiver-threshold-detect circuit are powered up. The

transmitter remains in an OFF state. The device is

ready to receive data as soon as the regulator is stabi-

lized, but not to transmit. If a microcontroller is being

driven by the voltage regulator output, it will go through

a POR and initialization sequence. The LIN pin is in the

recessive state for MCP2021/2 and in floating state for

MCP2021P/2P.

The device will stay in Ready mode until the output of

the voltage regulator has stabilized and the CS/LWAKE

pin is true (‘1’). After VREG is stable and CS/LWAKE is

high, MCP2021/2 will enter Operation mode; and

MCP2021P/2P will enter either Operation mode or

Transmitter-Off mode, depending on the level of the

FAULT/TXE pin (refer to Figure 1-4).

1.3.4

OPERATION MODE

In this mode, all internal modules are operational.

The device will go into the Power-Down mode on the

falling edge of CS/LWAKE.

For the MCP2021P/2P devices, the pull-up resistor is

switched on only in this mode.

Operation

Mode

Transmitter

Shutdown

LBUS

Voltage

Shutdown

Regulator

Output

Temperature <SHUTDOWNTEMP

Overload

to VBB

Overload

Temperature <SHUTDOWNTEMP

Note:

The above time interval <1.2 ms assumes

12V VBB input and no thermal shutdown

event.

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