Lambdatronic LT4
Functionsheet

Version 2.0 03/11/2022

Inhaltsverzeichnis

Inhaltsverzeichnis
1 Icons Description.............................................................................................................................................................

32 Pin Layout Life-Plug (AS 614 – 35 PN)..........................................................................................................................

43 Function Diagrams of Lambda Value Detection ..........................................................................................................

53.1

Lambda Main .........................................................................................................................................................................................................

53.2

Lambda Calc...........................................................................................................................................................................................................

53.3

Lambda Heat..........................................................................................................................................................................................................

63.4

Heatup Strategy....................................................................................................................................................................................................

63.5

LSU_TEMP_PLAUS ................................................................................................................................................................................................

7

3.6

Lambda Diagnosis................................................................................................................................................................................................

73.7

PWM Calc ................................................................................................................................................................................................................

73.8

Battery Voltage Detection.................................................................................................................................................................................

83.9

Lables ........................................................................................................................................................................................................................

83.10 Description..............................................................................................................................................................................................................

103.11 Typical Values ........................................................................................................................................................................................................

124 CAN Messages .................................................................................................................................................................

15

4.1

Send Messages......................................................................................................................................................................................................

154.2

Receive Messages ................................................................................................................................................................................................

164.3

Configuration of CAN Communication .......................................................................................................................................................

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1 Icons Description

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3 / 202 | Pin Layout Life-Plug (AS 614 – 35 PN)

2 Pin Layout Life-Plug (AS 614 – 35 PN)

4 / 20

PinFunction

1+12 V (Battery +)2+12 V (Battery +)3

Ground (Battery -)4Ground (Battery -)5

K-Line Diagnostic Connection

6CAN1 + (high)7

CAN1 – (low)8Analog out 1

9Analog out 210Analog out 311Analog out 412Reference GND for anal. out13Shield14Pump Current LSU1 IP115

Virtual GND LSU1 VM116Heater PWM LSU1 Uh-1

17

Heater (Batt +) LSU1 Uh+118

Setup Current LSU1 IA119

Nernst Voltage LSU1 UN120

Pump Current LSU2 IP221

Virtual GND LSU2 VM222

Heater PWM LSU2 Uh-2

23

Heater (Batt +) LSU2 Uh+224

Setup Current LSU2 IA225

Nernst Voltage LSU2 UN226

Pump Current LSU3 IP327

Virtual GND LSU3 VM328Heater PWM LSU3 Uh-329

Heater (Batt +) LSU3 Uh+330

Setup Current LSU3 IA331

Nernst Voltage LSU3 UN332

Pump Current LSU4 IP433

Virtual GND LSU4 VM434

Heater PWM LSU4 Uh-435

Heater (Batt +) LSU4 Uh+436

Setup Current LSU4 IA437

Nernst Voltage LSU4 UN4Lambdatronic_LT4_Functionsheet

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Function Diagrams of Lambda Value Detection | 3

3 Function Diagrams of Lambda Value
Detection
3.1 Lambda Main

3.2 Lambda Calc

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3.3 Lambda Heat

3.4 Heatup Strategy

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Function Diagrams of Lambda Value Detection | 3

3.5 LSU_TEMP_PLAUS

3.6 Lambda Diagnosis

3.7 PWM Calc

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3.8 Battery Voltage Detection

3.9 Lables

8 / 20afry

Air fuel ratio

B_can1OK

State of CAN1 chip

B_can2OK

State of CAN2 chip

batt_eError battery voltage detection

batt_uBattery voltage

batt_corr_uCorrection battery voltage

can_batt_u

Battery voltage via CAN

can_tmotEngine temperature via CAN

canlam_offset_dis

Inhibition flag for offset calibration (CAN Input)

canlamh_on

Lambda heaters switched on via CAN

CJ125diagy

Lambda-chip CJ125 internal error codelamy

Lambda value

lamy_eLambda value error

lamy_oLambda value calibration offset

lamy_ofLambda value calibration offset filteredlamy_uLambda sensor voltage

lamy_uc

Lambda sensor calibrated voltage

lamy_uf

Lambda sensor filtered voltage

lamyh_e

Lambda heater error

lamyh_modeHeater mode lambda probe

lamyh_u

Heater voltage lambda probe

lamyhpwm

Lambda heater PWM

lamyhu_p

Heater voltage lambda probe provisory

lamyhu_t

Heater voltage lambda probe from characteristic line

lamylimits_e

Lambda value beyond limits

lamyoffset_b

Lambda calibration active

lamyokLambda sensor operationallamyout_u

Lambda output voltage

lamypwm

Lambda PWM output value

lamyr

Lambda sensor internal impedancelamyr_f

Lambda sensor internal impedance filteredlamyr_uLambda sensor internal impedance voltage

lamyt

Lambda sensor temperature

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Function Diagrams of Lambda Value Detection | 3

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lamt_plaus

Plausible Lambda sensor temperature

lamyt_plaus_b

Measurable Lambda sensor temperature reachedlamt_humaxy_b

Conditition enabling maximum heating power lambda probe

lamytokLambda sensor operation temperature reachedtdlamyhTimer heatup phases for lambda probe 8

tdlamyh_max

Timer for heatup restriction time for lambda probe

BATT_U_CAN_CW

Battery voltage detection selection switch

BATT_U_DEF

Power supply voltage of LT4

BATT_U_MAX

Upper battery voltage threshold for plausibility check

BATT_U_MIN

Lower battery voltage threshold for plausibility check

CANENABLE_CWCAN enable

CANID

Lambda CAN messages IDs (reconfigurable)

CANRATECAN send frequency

CANSPEED_CWCAN baud rate (0->500 kBaud 1->1,000 kBaud)LAM_FIL

Lambda filter time-constant

LAM_LIN

Lambda value linearization curve

LAM_MAX

Lambda value maximum limit

LAM_MIN

Lambda value minimum limit

LAM_OPMODE_CW

Operating mode of Lamdatronic module channel x (lean/rich)

LAM_REF

Lambda calibration reference voltage

LAM_UAFR_FAK

Factor air fuel ration

LAMH_HEATUP

Heater voltage for heatup phase

LAMH_ON_CW

Activating lambda heater by codeword

LAMHDEW_xx

Lambda heater voltage for dewpoint phase

LAMHGRD_xx

Lambda heater gradient

LAMHOFF_xx

Lambda heater offset voltage

LAMHUxx

Lambda heater voltage predefined value

LAMHUMAX_xx

Lambda heater voltage maximum value

LAMHUMAXLOW_xx

Maximum heater voltage lower temperature range

LAMLIMITS_DEL

Lambda value delay for limits passing

LAMOFFSET_DEL

Lambda calibration duration

LAMOUTPWM

Linearization curve from pwm -> voltage conversion

LAMOUTU

Desired voltage output lambda -> voltage

LAMR_FIL

Lambda internal impedance filter time-constant

LAMR_GRD

Lambda internal impedance gradient

LAMR_OFF

Lambda internal impedance offset

LAMR_MAX

Maximum detectable resistance by LT4

LAMREF_DEL

Lambda calibration delay

LAMREF_FIL

Lambda calibration offset filter time-constant

LAMREF_MAX

Lambda value upper calibration limit

LAMREF_MIN

Lambda value lower calibration limit

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3 | Function Diagrams of Lambda Value Detection

LAMT_MIN

Lambda sensor minimum operation temperature

LAMTxx_LIN

Lambda sensor temperature linearization curve

LAMT_HEATUP_END

Temperature threshold for end of heatup phase

LAMH_HEATUP_BREAK

Heater voltage for heatup break phase

LAMT_HUMAXLOW_xx

Lower temperature threshold disabling high heating power

LAMT_HUMAX_xx

Upper temperature threshold for enabling high heating power

LAMTDIAG_MIN

Lambda sensor minimum temperature for diagnosis

LAMTMOT_DEW

Engine temperature threshold for dewpoint detection

LAMTYPE_CW

Lambda type (0->LSU 4.2 / 1->LSU 4.9 / 2-> Mini-LSU)

TDLAMH_DEW

Heating time for dewpoint phase

TDLAMH_HEATUP

Time for heatup phase

TDLAMH_HEATUP_BREA Time for heatup break phase
K
TDLAMH_MAX

Maximum time for Lambda probe heating

TDLAMH_MAX_ENA_CW Enable restriction of time for heatup break phase
TDLAMyH_MAX_RES_CW Reset variable for timer heatup restriction time for Lambda
probe yHints:– Variable names in table above containing a “y” are channel individual. Available arechannels 1 to 4.
– Parameter names in table above containing an “xx” are Lambda probe dependent.
Available are probes “42”, “49” and “49m”.

3.10 Description
Description
The LT4 Lambdatronic unit is lambda-control device created for use with the Boschlambda sensor LSU 4.2 / LSU 4.9 / Mini LSU 4.9. The unit consists of four CJ125 evaluation
IC’s (thereby allowing the use of up to 4 lambda sensors with a single LT4) and a microcontroller. The CJ125 outputs a voltage proportional to the pump current generated bythe lambda sensor. This voltage “lam_u” is a measure for the lambda value and is updated
every 10 ms. By relating “lam_u” to the linearization table “LAM_LIN”, the actual lambda
value “lam” is calculated and sent to the output.
An accurate reading of the exhaust lambda is only possible once the sensor has beenheated to an appropriate temperature (“lamt”). While the sensor is cold, a lambda value of
1 (“lam” = 1) will be indicated. Once the sensor has been heated to an appropriate temperature, the flag “lamok” will be indicated. For this to happen, the lambda sensor heater
must be operational. Lambda value accuracy can also be improved by selecting a lean orrich operating mode for the codeword “LAM_OPMODE_CW” depending on the application.
If any errors are detected by the CJ125’s internal diagnosis mechanisms, an error flag“lam_e” will be indicated. These error conditions include short-circuits, under-voltages andimplausible voltages for “lam_u” (note that this is only possible once the sensor temperature “lamt” has exceeded the setpoint “LAMTDIAG_MIN”). A properly-functioning sensor

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Function Diagrams of Lambda Value Detection | 3and CJ125 combination should result in an output voltage for “lam_u” between 0.2 and
4.0 volts. It is possible that voltages above or below this range can result from extreme exhaust mixtures (extreme enrichment or extremely lean conditions), in which case a delay“LAMLIMITS_DEL” is used for diagnosis detection.
The lambda sensor heater is switched on and off by the variables “LAMH_ON_CW” and“canlamh_on”. “LAMH_ON_CW” is the primary codeword for enabling the heaters. Ifswitched to “Heaters off”, the sensor heaters are disabled. If switched to “Heaters CANcontrolled”, the sensor heaters will be controlled via CAN. Please note that if CAN is not
being used for lambda sensor heater control, then selecting “Heaters CAN controlled” for“LAMH_ON_CW” will result in the sensor heaters being switched on by default. The variable “canlamh_on” is an indicator of the requested sensor heater operation mode overCAN. This is only an “on-off” flag.
Upon power initially being supplied to the LT4 and the lambda sensors, the sensor heaters
enter a dew point heating mode. A small effective voltage “LAMHDEW_xx” is supplied inorder to evaporate moisture that may have gathered around the sensing element. This
prevents sensor damage once full heater power is used to bring a sensor up to its operating temperature. The duration of this heating mode can be set using the variable“TDLAMH_DEW”. By default, dew point heating mode will always be activated upon
power-up. However, if engine temperature is supplied over CAN to the LT4 (indicated by
the variable “can_tmot”), this can be compared to the setpoint variable “LAMTMOT_DEW”
to determine whether dew point heating is required. If the engine temperature exceeds
the setpoint “LAMTMOT_DEW”, then dew point heating is skipped.
Once the dew point mode is complete (or if the dew point mode is skipped), the main
heating mode begins. The sensor heater effective voltage is ramped up from a setpoint“LAMHOFF_xx” according to a gradient “LAMHGRD_xx” until a maximum voltage “LAMHUMAX_xx” is reached. This effective voltage is maintained until the sensor is brought up
to its operating temperature, at which point the heater proceeds to a controlled heatingmode. The controlled heating mode varies the sensor heater effective voltage according
to the sensor temperature using the table “LAMHUxx” with the intent of maintaining thesensor’s optimum operating temperature (750°C LSU 4.2 / 780°C LSU 4.9 and Mini LSU
4.9). If the sensor temperature drops below the setpoint “LAMT_HUMAXLOW_xx”, thesensor heater will enter a safety mode where the main heating mode will be restarted. In
this case, the maximum voltage during the heater ramp is restricted according to the variable “LAMHUMAXLOW_xx”. This is done to keep heat in the sensor without damaging thesensing element.
The amount of current delivered to the lambda sensor heater is relative to the voltage ofthe power supply in order to protect the sensing element. The variables “BATTU_DEF” and“can_batt_u” represent this voltage information in the LT4. If power supply voltage information is available over CAN, this can be read into “can_batt_u”. Note that in order for CANsupplied voltage to be used, “BATTU_DEF” must be set to 0. If no power supply information is available over CAN, then “BATTU_DEF” should be set to the maximum expected
power supply voltage. If “BATTU_DEF” is set to 0 and no CAN information is supplied, theLT4 will default to an assumed voltage of 16 volts to protect the sensing element.
The lambda signal output is realized over both CAN and via an analog voltage output.
Further information regarding the CAN specification can be found in the section “CANmessages / CAN Botschaften” below. For the analog output, the table “LAMOUTU” relates
the lambda value to an output voltage (defined from 0 to 5 volts). To compensate for
hardware tolerances, the linearization table “LAMOUTPWM” can be used.

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3 | Function Diagrams of Lambda Value Detection

The LT4 has a new voltage compensation function. The LT4 will detect the voltage supply
from either “batt_u” or “can_batt_u”, the selection can be made in the parameter name“BATT_U_CW” in ModasSport. During operation the LT4 monitors the voltage value“BATTU_MIN” and “BATTU_MAX”. If the voltage drops below BATTU_MIN or raises above
the BATTU_MAX, the voltage value will then reset into default value call BATTU_DEF. The
voltage supply value must retain in between BATTU_MIN and BATTU_MAX. This function isto prevent any damage to the ceramic in the lambda probe due to excessive voltage supply.

NOTICEIf the analog output is desired rather than CAN, then it is necessaryto connect the analog ground from the LT4 to the battery ground.
The LT4´s analog ground is not internally connected to the supply ground.

3.11 Typical Values
BATT_U_CAN_CW=0

BATT_U_MAX= 18 V

BATT_U_MIN=3V

BATT_U_DEF= 14 VInternal battery voltage detection

Value of ”can_batt_u” is used todefine power supply

CANENABLE_CW=1

CANRATE= 10 ms

CANSPEED_CW= 1,000 kBaud

LAM_FIL= 20 ms

LAM_MAX= 4.5 VLAM_MIN= 0.2 VLAM_OP_MODE= “lean mode”

LAM_UAFR_FAK= 14.7

LAM_REF= 1.5 VLAMH_ON_CW= “CAN controlled”

CAN interface enabled

Heater is enabled without CAN
communication!

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LAMHU_DLIMHI= +10 V/sec

LAMHU_DLIMLO= -10 V/sec

LAMLIMITS_DEL=1s

LAMOFFSET_DEL= 0.15 s

LAMOFFSET_PER= 300 s

LAMR_FIL= 320 ms

LAMR_GRD= 408 Ohm/V

LAMR_OFF= 0.3 VLAMREF_DEL= 0.05 s

LAMREF_FIL= 0.011 s

LAMREF_MAX= 1.02

LAMREF_MIN= 0.98Lambdatronic_LT4_Functionsheet

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Function Diagrams of Lambda Value Detection | 3

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LAMT_MIN= 650°CLAMTDIAG_DEL= 10 sLAMTMOT_DEW= 50°CTDLAMH_DEW= 30 s

LAMTYPE_CW= “LSU 4.9”

lam_ucLAM_LIN

0.51

0.65

0.71

0.70

0.88

0.75

1.04

0.80

1.18

0.85

1.25

0.88

1.30

0.90

1.41

0.95

1.46

0.98

1.48

0.99

1.50

1.00

1.53

1.03

1.55

1.05

1.57

1.08

1.60

1.10

1.66

1.18

1.72

1.26

1.87

1.50

2.00

1.78

2.07

1.99

2.29

3.03

2.40

4.00

lam

LAMOUTU

0.2

0.2

0.4

0.4

0.6

0.6

0.8

0.8

11

1.2

1.2

1.4

1.4

1.6

1.61.8

1.822

2.2

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3 | Function Diagrams of Lambda Value Detection

2.4

2.4

2.6

2.6

2.8

2.8

33

3.2

3.2

3.4

3.4

3.6

3.6

3.8

3.8

44

4.4

4.4

4.6

4.6

Further application data have to be taken from datasheets of supported LSU types.

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CAN Messages | 44 CAN Messages
4.1 Send Messages
Using the CANID parameter line, the CAN messages can be reconfigured. Note that theseIDs must be in decimal form and not the usual hexadecimal one! To change an ID, simply
select the index number starting with 1 for ID1, 2 for ID2 and so on, and change the corresponding parameter-line value.

Default IDs
ID

ID1 (send)

ID2 (send)

CANID

0x770 (1904) unused

ID3 (send)

ID4 (send)

ID5 (receive)

0x772 (1906) 0x773 (1907) 0x774 (1908)

MESSAGE ID 1
Byte

Value

0

lam1 (low)1lam1 (high)2

lam2 (low)3

lam2 (high)4lam3 (low)5

lam3 (high)6

lam4 (low)7

lam4 (high)

MESSAGE ID 3Byte

Value

0

lam1t

1

lam2t

2

lam3t

3

lam4t

4-

5-

6-

7-

MESSAGE ID 4

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Byte

Value

0

lamx_e1lamxheat_e2

lamxok3

canlamheat_on

4

lamxoffset_b

5-

6-

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4 | CAN Messages

Notes 1
Configuration for Message ID 4 (“x” in each variable name designates a number 1 through4 indicating the applicable lambda sensor.)Bitlamx_elamxheat_elamxoklamxoffset_b0

lam1_elam1heat1_e

lam1oklam1offset_b1

lam2_elam2heat_e

lam2oklam2offset_b2

lam3_elam3heat_e

lam3oklam3offset_b3

lam4_elam4heat_e

lam4oklam4offset_b

4

-

---

5----

6----

7---

-

Notes 2– All values are unsigned (positive) values.
– All word-wide values are in Intel (little-endian) byte-order.
– All lambda-values are quantized with 0.000244/bit and zero offset (range = 0 to 16).
– All temperatures are quantized with 5°C/bit and offset -40°C (range = -40 to 1,235°C).
– The CAN refresh rate is 100 Hz (10 ms).

4.2 Receive Messages
This message can be used to switch off the lambda heaters by CAN command.
MESSAGE ID 5

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Byte

Value

0

canlamheat_on

1

canlam_offset_dis

2

batt_u

3

tmot

4-

5-

6-

7-

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CAN Messages | 4

Note 1
BitParameter0canlam_offset_dis channel 1

1canlam_offset_dis channel 22canlam_offset_dis channel 33canlam_offset_dis channel 44*canlam_offset_dis channel 55*canlam_offset_dis channel 66*canlam_offset_dis channel 77*canlam_offset_dis channel 8

NOTICEIf canlamheat_on and LAMHEAT_ON_CW equal 1: heaters areswitched on.
After 2 seconds time out of message ID 5 the heaters are switched on again.

4.3 Configuration of CAN Communication
CANSPEED_CW selects the baud rate of the CAN.
– CANSPEED_CW = 0: 500 kBaud– CANSPEED_CW = 1: 1,000 kBaud

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Bosch Engineering GmbH
Motorsport
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