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33989

System Basis Chip with High-Speed CAN Transceiver

Freescale Semiconductor 

ELECTRICAL CHARACTERISTICS

DYNAMIC ELECTRICAL CHARACTERISTICS

Table 4. Dynamic Electrical Characteristics (continued)

Characteristics noted under conditions 7.0 V ≤ VSUP ≤ 18 V, - 40°C ≤ TA ≤ 125°C, GND = 0 V unless otherwise noted. Typical

values noted reflect the approximate parameter means at TA = 25°C under nominal conditions unless otherwise noted.

Characteristic

Symbol

Min

Typ

Max

Unit

Non Differential Slew Rate (CANL or CANH)

Slew Rate 3

Slew Rate 2

Slew Rate 1

Slew Rate 0

V/µs

tSL3

4.0

19

40

tSL2

3.0

13.5

20

tSL1

2.0

8.0

15

tSL0

1.0

5.0

10

CANH

CANL

WU Receiver

Standby

Pulse Width Pulse OK

Filter

Narrow

Pulse

Counter

Latch WU

RST

RST

OUT

Timeout

+

Timeout

Generator

Figure 4. Wake-Up Block Diagram

The block diagram in Figure 4 illustrates how the wake-up

signal is generated. First the CAN signal is detected by a low

consumption receiver (WU receiver). Then the signal passes

through a pulse width filter which discards the undesired

pulses. The pulse must have a width bigger than 0.5 µs and

smaller than 500 µs to be accepted. When a pulse is

discarded the pulse counter is reset and no wake signal is

generated, otherwise when a pulse is accepted the pulse

counter is incremental and after three pulses the wake signal

is asserted.

LX

GND

1nF

10 k

Transient Pulse

Generator

(Note)

GND

Note: Waveform in accordance to

ISO 7637 part1, test pulses 1, 2, 3a and 3b.

Figure 5. Transient Test Pulse for L0:L3 Inputs

Each one of the pulses must be spaced by no more than

500 µs. In that case the pulse counter is reset and no wake

signal is generated. This is accomplished by the wake

timeout generator. The wake-up cycle is completed (and the

wake flag reset) when the CAN interface is brought to CAN

Normal mode.

The wake-up capability of the CAN can be disabled, refer

to SPI interface and register section, CAN register.

1nF

CANH

CANL

1nF

GND

Transient Pulse

Generator

(Note)

GND

Note: Waveform in accordance to

ISO 7637 part1, test pulses 1, 2, 3a and 3b.

Figure 6. Transient Test Pulses for CANH/CANL

Analog Integrated Circuit Device Data

Freescale Semiconductor

33989

15

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