L9805E datasheet(94/127 Pages) STMICROELECTRONICS

94 / 127 page

On-Chip Peripherals

L9805E

94/127

5.7.3

Functional Description

The Can Bus Transceiver is used as an interface between a CAN controller and the physical

bus. The device provides transmitting capability to the CAN controller. The transceiver has

one logic input pin (TX), one logic output pin (RX) and two Input/Output pins for the electrical

connections to the two bus wires (CAN_L and CAN_H). The microcontroller sends data to

the TX pin and it receives data from the RX pin. The transmission slew-rates of CAN_H and

CAN_L voltage are controlled to reduce RFI and EMI. The transceiver is protected against

short circuit or overcurrent: If ICANH and/or ICANL exceeds a current thresholds ISC, then the

CAN_H and CAN_L power transistors are switched off and the transmission is disabled for

TD=25µs typical.

5.7.4

CAN Transceiver Disabling function

The transceiver can be disabled and forced to move in a low power consumption mode,

setting CANDS bit in DCSR register. When the transceiver is in this mode it can not receive

nor transmit any information to the bus. The only way to have again on board the CAN

capabilities is reset CANDS bit. The CAN protocol handler can not disable nor enable the

transceiver and there is no way to communicate to the controller the transceiver is down.

The disabling function has the only purpose to allow the reduction of the current

consumption of the device in application not using the CAN at all or using it for particular

functions (such like debugging). Current consumption reduction, when disabling the

trasceiver, can be as high as 15mA.

Note When the CAN capabilities of L9805E are not needed additional consumption

reduction can be achieved putting the CAN controller in Stand-by Mode.

Figure 44.

Can Bus Transceiver Block Diagram

5.8

Power Bridge

5.8.1

Introduction

The power part of the device consists of two identical independent DMOS half bridges. It is

suited to drive resistive and inductive loads.

ŠŠ

−

TX0

RX0

CAN_H

CAN_L

OVERCURRENT

DETECTION

OVERCURRENT

DETECTION

POWER

CONTROL

VDD

GND

L9805E Datasheet(PDF) 94 Page - STMicroelectronics

L9805E Datasheet(HTML) 94 Page - STMicroelectronics

Html Pages

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75 76 77 78 79 80 81 82 83 84 85 86 87 88 89 90 91 92 93 94 95 96 97 98 99 100 ...More

Datasheet Download

Link URL