NCV7341D21R2G Datasheet NCV7341D21R2G, NCV7341D20R2G, NCV7341D20G | P7-P9

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Table 3. OPERATION MODES

Conditions Transceiver Behavior

Pin STB Pin EN

Undervoltage

Flag

VBAT

Undervoltage

Flag

Power−up or

Wakeup Flag

Operating Mode Pin INH

X X

Set X X Sleep Floating

Reset Set

Set Standby High

Reset

If in sleep, then no change Floating

otherwise stand−by High

Low Low Reset Reset

Set Stand−by High

Reset

If in sleep, then no change Floating

otherwise stand−by High

Low High Reset Reset

Set Stand−by High

Reset

If in sleep, then no change Floating

otherwise go−to−sleep High

High Low Reset Reset X Receive−only High

High High Reset Reset X Normal High

Normal Mode

In Normal mode, the transceiver is able to communicate

via the bus lines. The CAN controller can transmit data to the

bus via TxD pin and receive data from the bus via Pin RxD.

The bus lines (CANH and CANL) are internally biased to

/2 via the common−mode input resistance. Pin V

SPLIT

is also providing voltage V

/2 which can be further used

to externally stabilize the common mode voltage of the bus

– see Figure 2 and Figure 3. Pin INH is active (pulled high)

so that the external regulators controlled by INH Pin are

switched on.

Receive−Only Mode

In Receive−only mode, the CAN transmitter is disabled.

The CAN controller can still receive data from the bus via

RxD Pin as the receiver part remains active. Equally to

normal mode, the bus lines (CANH and CANL) are

internally biased to V

/2 and Pin V

SPLIT

is providing

voltage V

/2. Pin INH is also active (pulled high).

Standby Mode

Standby mode is a low−power mode. Both the transmitter

and the receiver are disabled and a very low−power

differential receiver monitors the CAN bus activity. Bus

lines are biased internally to ground via the common mode

input resistance and Pin V

SPLIT

is high−impedant (floating).

A wake−up event can be detected either on the CAN bus or

on the WAKE Pin. A valid wake−up is signaled on pins ERR

and RxD. Pin INH remains active (pulled high) so that the

external regulators controlled by INH Pin are switched on.

Go−To−Sleep Mode

Go−To −Sleep mode is an intermediate state used to put the

transceiver into sleep mode in a controlled way.

Go−To −Sleep mode is entered when the CAN controller

puts pin EN to High and STB

Pin to Low. If the logical state

of Pins EN and STB

is kept unchanged for minimum period

of t

h(min)

and neither a wake−up nor a power−up event occur

during this time, the transceiver enters sleep mode. While in

go−to−sleep mode, the transceiver behaves identically to

stand−by mode.

Sleep Mode

Sleep mode is a low−power mode in which the

consumption is further reduced compared to stand−by

mode. Sleep mode can be entered via go−to−sleep mode or

in case an undervoltage on either V

or V

occurs for

longer than the under−voltage detection time. The

transceiver behaves identically to standby mode, but the

INH Pin is deactivated (left floating) and the external

regulators controlled by INH Pin are switched off. In this

way, the V

BAT

consumption is reduced to a minimum. The

device will leave sleep mode either by a wake−up event (in

case of a CAN bus wake−up or via Pin WAKE) or by putting

Pin STB

high (as long as an under−voltage on V

or V

is not detected).

Internal Flags

The transceiver keeps several internal flags reflecting

conditions and events encountered during its operation.

Some flags influence the operation mode of the transceiver

(see Figure 5 and Table 3). Beside the undervoltage and the

TxD dominant timeout flags, all others can be read by the

CAN controller on Pin ERR

. Pin ERR signals internal flags

depending on the operation mode of the transceiver. An

overview of the flags and their visibility on Pin ERR

is given

in Table 4. Because the ERR

Pin uses negative logic, it will

be pulled low if the signaled flag is set and will be pulled

high if the signaled flag is reset.

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Table 4. INTERNAL FLAGS AND THEIR VISIBILITY

Internal Flag Set Condition Reset Condition Visibility on Pin ERR

Undervoltage V

< V

CC(SLEEP)

longer than t

UV(VCC)

or V

< V

IO(SLEEP)

longer than t

UV(VIO)

At wake−up or power−up No

BAT

Undervoltage V

BAT

< V

BAT(STB)

When V

BAT

recovers No

Powerup V

BAT

rises above VBAT

(PWUP)

BAT

connection to the transceiver)

When normal mode is

entered

In receive−only mode. Not

going from normal mode

Wake−up When remote or local wake−up is

detected

At power−up or when normal

mode is entered or when

undervoltage flag is

set

Both on ERR and RxD (both

pulled to low). In

go−to−sleep, standby and

sleep mode.

Local Wake−up When local wake−up is detected

(i.e.via pin WAKE)

At power−up or when leaving

normal mode

In normal mode before 4

consecutive dominant

symbols are sent. Then ERR

pin becomes High again

Failure Pin TxD clamped low or

overtemperature

When entering normal mode

or when RxD is Low while

TxD is high (provided all

failures disappeared)

Overtemperature condition

observable in receive−only

mode entered from normal

mode

Bus Failure

(NCV7341D20)

One of the bus lines shorted to ground

or supply during four consecutive

transmitted dominants

No bus line short (to ground

or supply) detected during

four consecutive dominant bit

transmissions

In normal mode

Undervoltage Flag

The V

undervoltage flag is set if V

supply drops

below V

CC(sleep)

level for longer than t

UV(VCC)

or V

supply drops below V

IO(sleep)

level for longer than t

UV(VIO)

If the flag is set, the transceiver enters sleep mode. After a

waiting time identical to the undervoltage detection times

UV(VCC)

and t

UV(VIO)

, respectively, the flag can be reset

either by a valid wake−up request or when the powerup flag

is set. During this waiting time, the wakeup detection is

blocked.

VBAT Under−voltage Flag

The flag is set when V

BAT

supply drops below V

BAT(STB)

level. The transceiver will enter the standby mode. The flag

is reset when V

BAT

supply recovers. The transceiver then

enters the mode defined by inputs STB

and EN.

Power−up Flag

This flag is set when V

BAT

supply recovers after being

below V

BAT(PWUP)

level, which corresponds to a

connection of the transceiver to the battery. The V

undervoltage flag is cleared so that the transceiver cannot

enter the Go−to−sleep Mode, ensuring that INH Pin is high

and the external voltage regulators are activated at the

battery connection. In Receive−only mode, the powerup

flag can be observed on the ERR

Pin. The flag is reset when

Normal mode is entered.

Wake−up Flag

This flag is set when the transceiver detects a valid

wake−up request via the bus or via the WAKE Pin. Setting

the wake−up flag is blocked during the waiting time of the

undervoltage flag. The wake−up flag is

immediately propagated to Pins ERR

and RxD – provided

that supplies V

and V

are available. The wake−up flag

is reset at power−up or when V

undervoltage occurs

or when Normal mode is entered.

Local wake−up Flag

This flag is set when a valid wake−up request through

WAKE Pin occurs. It can be observed on the ERR

Pin in

normal mode. It can only be set when the powerup flag is

reset. The local wake−up flag is reset at powerup or at

leaving Normal mode.

Failure Flag

The failure flag is set in one of the following situations:

• TxD Pin is Low (i.e. dominant is requested by the CAN

controller) for longer than t

dom(TxD

) − Under this

condition, the transmitter is disabled so that a bus

lockup is avoided in case of an application failure

which would drive permanent dominant on the bus. The

transmitter remains disabled until the failure flag is

reset.

• Overtemperature − If the junction temperature reaches

J(SD)

, the transmitter is disabled in order to protect it

from overheating and the failure flag is set. The

transmitter remains disabled until the failure flag is

reset.

The failure flag is reset when Normal mode is entered or

when TxD pin is High while RxD pin is Low. In case of

overtemperature, the failure flag is observable on pin ERR

Bus Failure Flag (NCV7341D20)

The transmitter of the NCV7341D20 device version

allows bus failure detection. During dominant bit

transmission, a short of the CANH or CANL line to ground

or supply (V

, VBAT or other) is internally detected. If the

short circuit condition lasts for four consecutive dominant

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transmissions, an internal bus failure flag is set and made

immediately visible through a Low level on the ERR

pin.

The transmission and reception circuitry continues to

function.

When four consecutive dominant transmissions succeed

without a bus line short being detected, the internal bus

failure flag is reset and ERR

pin is released to High level.

Split Circuit

The V

SPLIT

Pin is operational only in normal and

receive−only modes. It is floating in standby and sleep

modes. The V

SPLIT

can be connected as shown in Figure 2

and Figure 3 and its purpose is to provide a stabilized DC

voltage of V

/2 to the bus avoiding possible steps in the

common−mode signal, therefore reducing EME. These

unwanted steps could be caused by an unpowered node on

the network with excessive leakage current from the bus that

shifts the recessive voltage from its nominal V

/2 level.

Wake−up

The transceiver can detect wake−up events in stand−by,

go−to−sleep and sleep modes. Two types of wake−up events

are handled – remote wake−up via the CAN bus or a local

wake−up via the WAKE pin. A valid remote wake−up is

recognized after two dominant states of the CAN bus of at

least t

dom

, each of them followed by a recessive state of at

least t

rec

A local wake−up is detected after a change of state (High

to Low, or Low to High) on WAKE Pin which is stable for

at least t

WAKE

. To increase the EMS level of the WAKE Pin,

an internal current source is connected to it. If the state of the

WAKE Pin is stable at least for t

WAKE

, the direction of the

current source follows (pulldown current for Low state,

pullup current for High state). It is recommended to connect

Pin WAKE either to GND or VBAT if it’s not used in the

application.

Fail Safe Features

Fail safe behavior is ensured by the detection functions

associated with the internal flags.

Furthermore, a current−limiting circuit protects the

transmitter output stage from damage caused by accidental

short circuit to either positive or negative supply voltage,

although power dissipation increases during this fault

condition.

The Pins CANH and CANL are protected from

automotive electrical transients (according to ISO 7637; see

Figure 9). Pins TxD is pulled high and Pins STB

and EN are

pulled low internally should the input become disconnected.

Pins TxD, STB

, EN and RxD will be floating, preventing

reverse supply should the V

supply be removed.

P1-P3 P4-P6 P7-P9 P10-P12 P13-P15 P16-P18

NCV7341D21R2G

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Manufacturer:

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Description:

CAN Interface IC HS LP CAN TRANSC.

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