ON Semiconductor NCV7694 User Manual

Safety Controller for
Infra-Red LED Illumination
to Complement the Image
Sensor for Automotive
Applications

NCV7694

The NCV7694 is a device which can drive a string of infra−red
LEDs using an external mosfet. The IR LEDs are used to illuminate
the surroundings of the image sensor. Since these LEDs can damage
the end users’ eyes, the power feed to the LEDs needs to be turned off
during a fault condition.

The NCV7694 driver features prevents the IR LEDs from being on
too long due to an inappropriate exposure time or being turned on too
frequently using external resistors. The value of the R
defines the maximum T
value of the R

resistor defines the maximum frequency of the

FRL

time of the emitted light intensity and the

ON

FLASH signal from the image sensor.

A LED driver with hardware interlocks helps protect the users’ eyes
in cases where the control signal has failed or a fault in the LED power
path has occurred.

LED brightness level is easily programmed using an external
resistor in series with the mosfet transistor.

The device can also detect Open Load, Short Circuit to GND and
VS. Faults are reported to the DIAG pin, which can directly disable the
DC/DC converter to prevent possible damage.

The device is available in 10 pin DFN package.

Features

• Constant Current Output for LED String Drive

• FLASH Input Pin

• Open LED Diagnostic Detection

• Short LED to GND and VS Detection

• Safety Feature Prevent Being ON too long

• Safety Feature Prevent Being ON too frequently

• External Resistor Defining max ON time

• External Resistor Defining min OFF time

• Protection against Short to Ground and Open of the External Resistors

• Detection and Protection Against Under−Voltage and over

Temperature

• AEC−Q100 Qualified and PPAP Capable

• ASIL−A safety design, ISO26262 compliant

• 10 Pin Packaging

• Wettable Flank Package for Enhanced Optical Inspection

• These are Pb−Free Devices

Applications

• In−Cabin Monitoring Sensor

• Infrared Illumination for Automotive Cameras

• Machine Vision Systems

• Surveillance Systems

ETL

resistor

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1

DFNW10, 3x3, 0.5P

CASE 507AG

MARKING DIAGRAM

NV76

94−0

ALYW

S

NV7694−0 = Specific Device Code
A = Assembly Location
L = Wafer Lot
Y = Year
W = Work Week
S = Pb−Free Package

PIN CONNECTIONS

1

VS

DIAG

FLASH

R

ETL

R

FRL

ORDERING INFORMATION

Device Package Shipping

NCV7694MW0R2G DFN10

†For information on tape and reel specifications,

including part orientation and tape sizes, please
refer to our Tape and Reel Packaging Specification
Brochure, BRD8011/D.

NCV7694

2

3

4

5

Top View

(Pb−Free)

V

10

STRING

9

DET

GATE

8

7

FB

GND

6

2500 / Tape &

Reel

†

© Semiconductor Components Industries, LLC, 2020

February, 2021 − Rev. 2

1 Publication Order Number:

NCV7694/D

NCV7694

VS

V

BAT

C

SUPPLY

VDD_MCU

controller /

Supply for MCU and Image Sensor

VDD_MCU

Micro−

Data

interface

VDD_AR

VDD_AR

Image Sensor

AR 0135

DSP

Diag detection

GND

GND

VDD_MCU

R2

20k

FLASH

Define max

exposure time

VS

FLASH

DIAG

R

ETL

R3

R4

R

FRL

Define max
frequency

NCV7694

GND

R

EMC1

VSTR

1 kW

R

EMC2

DET

1 kW

R

EMC3

GATE

200 W

R

EMC4

FB

750 W

Note1: 4x optional
EMC shield resistors

Note2: Optional Zener diode

Q1

ZD

NVTFS5C478NL

R1

Figure 1. Application Diagram − Powered Directly from Battery

V

BAT

C

SUPPLY

VDD_MCU

Micro−

controller /

DSP

GND

Supply for MCU and Image Sensor

Data

interface

VDD_AR

VDD_AR

Image Sensor

VDD_MCU

AR 0135

Diag detection

GND

exposure time

VDD_MCU

20k

FLASH

Define max

R2

FLASH

R3

R4

DIAG

R

ETL

R

FRL

Define max
frequency

VS

NCV7694

GND

EN

C1

DC /DC

NCV898031

VString

R

VSTR

DET

GATE

FB

EMC1

1 kW

R

EMC2

1 kW

R

EMC3

200 W

R

EMC4

750 W

Note1: 4x optional
EMC shield resistors

Note2: Optional Zener diode
for Mosfet Gate protection

NVTFS5C478NL

ZD

R1

Figure 2. Application Diagram − using DC/DC

RECOMMENDED EXTERNAL COMPONENTS FOR THE APPLICATION DIAGRAM

Component Function Min Typ Max Unit

C1 Decoupling capacitor 100 nF

R1 FB current sense resistor 100

R2 DIAG pull−up resistor 20

R3 Resistor for Exposure Time Limitation 0.8 15

R4 Resistor for Frame Rate Limitation 0.8 15

REMC1 Optional EMC shield resistor for VSTR pin 1000

REMC2 Optional EMC shield resistor for DET pin 1000

REMC3 Optional EMC shield resistor for GATE pin 200

REMC4 Optional EMC shield resistor for FB pin 750

(Note 1) Optional EMC serial resistor shall be used in case
if the LEDs are detached far away from the NCV7694
device. The resistors improves the EMC susceptibility of the
application.

(Note 2) Optional Zener diode may be used if the VS
supply is higher than V

voltage of the external transistor.

GS

In case of Open Load on the LEDs, the GATE voltage will
go high, the Zener diode will limit the maximum voltage

Figure 1 shows an example of the typical output drive
configuration. The current through the external LEDs is
equal to

I

= VFB / R

LEDs

1

Where:

• V

is internal feedback reference = 300 mV

FB

• R

is feedback resistor which set the current

1

during eventual Open Load condition.

mW

kW

kW

kW

W

W

W

W

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2

Block Diagram

Exposure

Time Limit

FLASH

DIAG

R

ETL

VS

Supply

monitoring

R

FLASH

R

=

t

ETL

K

ETL

ETL

NCV7694

Controlling,

Monitoring,

Filtering &

decoding

SC

= V

th

str

Short Circuit

LED − Vstr

Short Circuit

LED − GND

V

SVth

1.22 V

− 1.22 V

V

SGth

R

350 mV

GATE

V

STRING

DETPull−up

R

DET

GATE

R

FRL

Frame Rate

Limit

t

f

RTL

FRL

R

=

K

= 1/ t

FRL

FRL

FRL

Open Load

GND

Figure 3. Simplified Block Diagram

FB

reference

V

FBref

300mV

V

FB

150 mV

OLth

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3

Timing Characteristics

e.g.: 45 Hz = 22 .2 ms period

NCV7694

FLASH

ET threhsold

Exposure Time

Counter

FR threshold

Frame Rate
Counter

Typical pulse

t

ETL

Too long pulse

Short pulseTypical pulse

Double frequency pulse

t

FRL

LED output

Typical pulse Short pulse

Figure 4. Simplified Internal Timing Characteristic of the Internal ETL, FRL Counter

Safety Feature Behavior

External Resistor Approach

The resistor (RETL, RFRL) creates bias voltage on the
pins. Internal oscillator speed is derived from value of the
resistors. While FLASH signal is high, internal ETL counter
is counting and when the threshold is exceeded, the output
is disabled. When FLASH pin is low, the Frame Rate timer
is starting to count. The next rising edge of the FLASH
signal is propagated to the output only if FRL timer expires.

Rest of the pulse

is cut−OFF because “ET”

counter exceed the

threshold

The period of the internals counters can be adjusted by
external resistors.

Total tolerance of the maximum T
Rate limits will be affected by internal accuracy and
accuracy of the external resistor by following equation:
Using 1% external resistor approximately 13% tolerance
can be achieved.

a

TOTAL

Driver is activated with

next rising edge of

FLASH pulse

2

Ǹ

+ a

device

) a

2

+ 13.02) 1

resistor

Second pulse is cut off

because “FR” counter is

not reach the threshold

or maximum Frame

ON

Ǹ

2

+ 13.04 %

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4

NCV7694

PIN FUNCTION DESCRIPTION

10−pin DFN10

Package

Pin # Label Description

1 VS Supply voltage of the device

2 DIAG Diagnostic output

3 FLASH Logic input for flash exposure time

4 R

5 R

ETL

FRL

6 GND Ground

7 FB Feedback reference input 300 mV.

8 GATE Gate drive for external mosfet

9 DET LED short detection input

10 V

STRING

MAXIMUM RATINGS

Symbol Parameter Min. Max. Unit

Vmax_VS Continuous supply voltage

Vmax_FLASH Low Voltage Input pin −0.3 +3.6 V

Vmax_GATE Output voltage (during Open Load condition) −0.3 +VS V

Vmax_R

ETL

, R

FRL

Vmax_FB Low Voltage Input pin −0.3 +3.6 V

Vmax_DIAG Open Drain pin −0.3 +40 V

Vmax_DET,

V

STRING

Tjmax Junction Temperature, T

Stresses exceeding those listed in the Maximum Ratings table may damage the device. If any of these limits are exceeded, device functionality
should not be assumed, damage may occur and reliability may be affected.

1. Maximum ratings are those values beyond which device damage can occur. Maximum ratings applied to the device are individual stress limit
values (not normal operating conditions) and are not valid simultaneously. If these limits are exceeded, device functional operation is not
implied, damage may occur and reliability may be affected.

Transient Voltage (t < 500 ms, “load dump”)

DC voltage on Resistors −0.3 +3.6 V

High Voltage Input pin −0.3 +40 V

External resistor defines maximum Exposure Time Limit

External resistor defines maximum Frame Rate Limit

Short circuit reference voltage

−0.3

−

J

−40 +125

+40
+40

V
V

°C

ATTRIBUTES

Parameer Value Unit

ESD Capability (Note 2)

HBM (Human Body Model)
CDM (Charge Device Model)
MM (Machine Model)

≥ ±4.0
≥ ±1.0

≥ ±200

kV
kV

V

Moisture Sensitivity (DFN10−EP) (Note 3) 1 MSL

Storage Temperature Range −40 to 150 °C

Package Thermal Resistance (DFN10−EP) (Note 4)

− Junction to Ambient, R

− Junction to Board, R

− Junction to Case (Top), R

q

q

JB

JA

q

JC

62.5

5.5

2.7

°C/W
°C/W
°C/W

Ambient Temperature −40 to 105 °C

2. This device series incorporates ESD protection and is tested by the following methods:

ESD HBM tested per AEC−Q100−002 (EIA/JESD22−A114)
ESD CDM tested per EIA/JES D22/C101, Field Induced Charge Model
ESD MM according to AEC−Q100

3. For additional information, see or download ON Semiconductor’s Soldering and Mounting Techniques Reference Manual, SOLDERRM/D,
and Application Note AND8003/D.

4. Values represent thermal resistances under natural convection are obtained in a simulation on a JEDEC−standard, 2S2P; High Effective
Thermal Conductivity Test Board as specified in JESD51−7, in an environment described in JESD51−2a.

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5

NCV7694

ELECTRICAL CHARACTERISTICS

(

7 V < VS < 28 V, R

R1 = 100 mW, −40°C ≤ T

GENERAL

Supply Voltage

Supply Under−Voltage Lockout VSUV VS rising 4.0 4.5 5.0 V

Supply Under−Voltage hysteresis VSUVhys 150 300 550 mV

Supply Current in normal condition I_VS

Supply Current in Fault condition I_VSerr VS = 14 V,

Thermal Shutdown (TSD) 130 150 170

Thermal Hysteresis − 15 −

FB DRIVER

FB Regulation reference
Gate ON voltage V

Propagation Delay
FLASH rising – FB ON

Propagation Delay
FLASH falling – FB OFF

FLASH propagation Delay Delta t

Output pull−down resistance R

FLASH INPUT PIN

Input High Threshold
Input Low Threshold V
Input pull−down resistance R

PROGRAMMING

R

Bias voltage V

ETL

ETL resistor operation range R

Maximum TON time (typ) T

ETL multiplication K

K

tolerance tol

ETL

Overcurrent protection R

Open Load protection R

= 4.99 kW, R

ETL

≤ 125°C, unless otherwise specified)

J

Characteristic

ETL

ETL

=1.96 kW, 4 V < V

FRL

< 28 V, Transistor = NVTFS5C478NL, LED = SFH 4725AS,

STRING

Symbol Conditions Min. Typ. Max. Unit

VS_OP Parametric operation 7 − 28 V

VS = 14 V,

− 4.0 6.0 mA
FLASH = High,
I

, I

FRL

VS = 14V,

subtracted

ETL

− 3.8 6.0 mA
FLASH = Low,
I

, I

FRL

subtracted

ETL

− 4.0 6.0 mA
FLASH = High,
Open Load condition,
I

, I

subtracted

ETL

4.5 − − V

− 1.4 4

V

FBref

GATE

t

ON

t

OFF

pd_delta

FRL

Under Voltage Lockout < VS 270 300 330 mV
FB = 220 mV,

DET = 1.0 V
50% criterion − 8 15

50% criterion − 6.6 15

|(Falling time) –
(Rising Time)|

50% criterion

GATE

V

inH

inL

FLASH

ETL

ETL

ONmax

ETL

ETL

I

ETL_lim

I

ETL_open

5 30 100

1.3 1.2 − V

− 1.15 1.1 V
30 120 190

I

ETL

V

+

R

ETL

ETL

1.0

+

4990

+ 200.4 mA

external resistor value operation

− 1.0 − V

0.8 − 15

range
for R
for R
Derived from R

valid for

K

t

ETL

ETL

= 800 W => t

ETL

= 15 kW => t

ETL

R

ETL

R

ETL

+

t

ETL

R

ETL

+

K

ETL

and K

ETL

= 15 kW

4.99

+

2.5

= 320 ms;

ETL

= 6 ms

ETL

ETL(typ)

+ 1.996 ms

;

− − 6.0 ms

− 2.5 −

Tolerance of Exposure Time Limit ±13.0 %
Short to ground

1.3 − − mA

Resistor detection for

< 750 W

R

ETL

Open Load detection

− − 57.5
Resistor detection for

> 17.5 kW

R

ETL

°C

°C

μs

μs

μs

kW

kW

kW

kW/s

mA

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6

ELECTRICAL CHARACTERISTICS

(

7 V < VS < 28 V, R

R1 = 100 mW, −40°C ≤ T

PROGRAMMING

FRL resistor
operation range

= 4.99 kW, R

ETL

≤ 125°C, unless otherwise specified)

J

FRL

Characteristic UnitMax.Typ.Min.ConditionsSymbol

=1.96 kW, 4 V < V

R

FRL

NCV7694

< 28 V, Transistor = NVTFS5C478NL, LED = SFH 4725AS,

STRING

external resistor value operation
range

for R

FRL

(10 ms)
for R

FRL

(100 ms)

= 1 kW => f

= 10 kW => f

FRL

FRL

=100 Hz

=10Hz

0.8 − 15

kW

Maximum FLASH Frequency (typ) f

FRL multiplication K

K

tolerance tol

FRL

Overcurrent protection R

Open Load protection R

FRL

FRL

I

I

FRL_open

OPEN LOAD / SHORT TO GND

Open Load Detection Threshold (FB pin)
Open Load

t

Blanking Time
Short to GND Detection Threshold

(DET pin)
Short to GND

t

Blanking Time

SHORT CIRCUIT

Short to V

Detection Threshold V

STRING

Short Circuit Blanking Time t
Input pull−up resistor on DET pin R

DETPull−up

DIAG OUTPUT

V

diagnostic activation threshold V

STRING

max

FRL

FRL

FRL_lim

V

OLth

OLBlank

V

SGth

SGBlank

SCth

SCBlank

STRth

Derived from R
valid for R

R

K

+

FRL

t

R

t

f

FRL

FRL

FRL

+

K

FRL

1

+

t

FRL

FRL

FRL

FRL

+

+

and K

FRL

= 800 W

1.96

0.1

1

0.0196

FRL(typ)

+ 19.6 ms

+ (51 Hz)

;

− − 125 Hz

−

0.1

−

Tolerance of Frame Rate Limit ±13.0 %
Short to ground

1.3 − − mA

Resistor detection for

< 750 W

R

FRL

Open Load detection

− − 57.5
Resistor detection for

> 17.5 kW

R

FRL

FLASH = High 130 150 170 mV

10 22 35

FLASH = Low 300 350 400 mV

5 10 15

FLASH = High V

ING

STR

1.5

V

−

ING

1.22

STR

V

STR

−

ING

0.9

−

5 10 15

Pull−up to V

V

voltage 2.0 2.2 2.4 V

STRING

STRING

30 120 190

mA

ms

ms

V

ms

kW

Output low level V

OUTL

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Fault is present,

I

DIAG

7

= 0.33 mA

− 0.2 0.4 V

NCV7694

PINS DESCRIPTION

FLASH

Flash Input pin is compatible with 1.8 V / 2.8 V logic of
the ON Semiconductor image sensors. Internal pull down
resistor is implemented to prevent unwanted switch on.
Based on the R

ETL

and R

resistors, the maximum T

FRL

ON

FLASH time which can be propagated to the output is 6 ms
and minimum T

time, which will can be set, is typically

OFF

8 ms. The NCV7694 can be used as companion device for
60 Hz camera sensors in full FLASH T
with limited T

DIAG

ON

range.

range or 120 Hz

ON

Open Drain DIAG pin can be connected with pull up
resistor to MCU which will be informed about a fault in case
of Open Load, Short to V

or Short to Ground of the

STRING

LEDs. Diagnostic pin can be connected to the Enable pin of
the DC/DC converter. The output V

STRING

voltage will be
disconnected and user and devices are protected against
damages. The NCV7694 driver can also inform the system
while FLASH pulse is too long or is send too frequent. The
Open Load and Short circuit detections of the R

ETL

, R

FRL

timing resistors are reported on the DIAG pin as well as the
Thermal Shutdown Flag and Under Voltage status on the VS
supply.

DET

Detection pin is sensing the voltage at the cathode of the

LEDs. The voltage on DET pin during the FLASH−ON
period should be in range from V
(V
Short to ground and above V
will detect Short LEDs to V

– 1.22 V). Below 0.35 V the device will detect

STRING

STRING

STRING

(0.35 V) to V

SGth

SVth

minus 1.22 V the device

.

In case of DET pin is disconnected, device will go into

fault because internal pull−up to V

is implemented.

STRING

Short to ground can be detected only when output is not

activated.

FB

A feedback loop regulates the current through the external
LEDs. The voltage across the external sense resistor is
regulated to the 300 mV typ. Using FB pin can be detected

Open Load condition, if the when FB voltage will be below
threshold for longer than blanking time. It is not allowed to
put external voltage higher than 0.19 V on the FB pin when
the device is not active. The voltage on the FB pin has to be
below 0.19 V during VS supply ramp up while FLASH
PWM signal is already present.

GATE

The NCV7694 can drive MOSFET transistors with
minimum GATE voltage of 4.5 V. The preferred mosfet
transistor is NVTFS5C478NL.

R

and R

ETL

FRL

To reduce thermal retina hazard and thermal injury risk of
the cornea, the safety turn−off function is implemented.
External R

ETL

and R

resistor defines maximum

FRL

exposure time and maximum frame rate. The maximum
times are calculated using resistor values of the R

resistors divided by K

R

FRL

FRL

or K

coefficients. If the

ETL

ETL

and

FLASH pulse is permanently HIGH, the output pulse is
being activated only after FRL timer expire and during the
allowed ETL time period.

Short and Open on the R

ETL

and R

FRL

To be able detect the defect on the external resistors the
Open Load and Short to Ground detections are implemented
in the NCV7694. If the resistor value will be below 750 W,
short to ground will be detected. If the resistor value
becomes higher than 17.5 kW, Open Load is detected.

As soon as a fault condition is detected, then after a short
filter time the driver is switched off and fault on the DIAG
pin is reported

V

STRING

High voltage input pin sense the voltage on the top of the
LEDs and enable the Open Load and Short diagnostic as
soon as the voltage exceed the threshold VSTRth >2.2 V. If
DC/DC converter is not used, the VSTRING voltage has to
be connected to the VS pin. If the LED diagnostic is not
required, then the VSTRING pin has to be grounded.

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8

NCV7694

DETAILED OPERATING DESCRIPTION

Under Voltage Lockout

Under voltage Lockout feature is used to protect against
an abnormal status during startup. When the initial soft start
voltage is greater than 4.5 V (typ) the device starts to be
active. Below this threshold the GATE output pin is pulled
low to ground to prevent opening external N−MOS
transistor and DIAG pin is pulled low to report.

Thermal Shutdown

The thermal shutdown circuit checks the internal junction
temperature of the device. When the internal temperature
rises above the Thermal shutdown threshold, then after a

short filter time the driver is switched off and fault on the
DIAG pin is reported.

Exceeding the Flash Pulse

If the duration of the FLASH pulse exceeds the
pre−defined timing or the FLASH pulse repetition is too
frequent, the GATE of the transistor is switched off. The
limitation of the FLASH pulses is also reported on the DIAG
pin. The first FLASH pulse after power−on−reset should be
delayed longer than FRL period, otherwise the FLASH
pulse will be limited and DIAG pin will report a fault until
FRL counter expires.

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9

Open Load Detection

V

BAT

NCV7694

VDD_MCU

20 kW

FLASH = High

FLASH

DIAG

Define

exposure

R2

R3

max

time

FLASH

R4

Define

max

frequency

DIAG

R

R

FRL

ETL

VS

GND

Figure 5. Open Load Detection Circuit

When Open Load fault is introduced during

FLASH = High and V

STRING

> V

, the 22 ms blanking

STRth

time eliminate the false faults. When blanking time expires,
the NCV7694 immediately report a fault on the DIAG pin.
The output GATE pin remains active. The DIAG pin is
recovered with the falling edge on the FLASH pin or after
ETL counter is expired.

If EN pin of the DC/DC converter is connected to the
DIAG output, the Open Load causes switching OFF the
V

voltage. The DIAG pin is recovered as soon as

STRING

FLASH pin goes low or ELT counter expired. It will take

> V

VFB <

V

STRING

STRth

150 mV

Open Load

R1

EN

C1

NCV7694

DC /DC

NCV898031

VSTR

V

STRING

DET

GATE

FB

approximately 2 ms to re−activate the DC/DC V
voltage of the converter. With typical FRL setting, the driver
will be ready to perform the diagnostic on the next FLASH
pulse.

If the ENable of the DC/DC converter is not driven by

NCV7694, the Open Load is reported to the DIAG pin.

Diagnostic is not active when V

STRING

< V

STRth

FLASH pulse will not be detected when driver is going to be
recovered from a Short to GND fault because the DC/DC
converter in not fully active.

STRING

. The first

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10

STRING

V

DET

V

V

STRth

2.2 V

NCV7694

OPEN LOAD BEHAVIOR

Conditions: VS powered, DC /DC used, EN connected to the DIAG pin

Open Load present

input

FLASH

GATE

V

DIAG

V

FLASH is

propagated

to the output

t

DC_EN

Fault is present

and detected

LED is OFF

t

OLBlank

t

DC_EN

t

= 1.5 ms activation delay of the DC/DC

DC_EN

V

STRING

is not

sufficient, Open

Load isn’t detected

Figure 6. Timing of the Open Load Behavior

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11

NCV7694

Short to Ground

In case of short to ground, huge amount of current is
passing through the LEDs. To protect the LEDs and Human
eyes, the safety mechanism can be implemented. The DIAG

V

BAT

VDD_MCU

20 kW

FLASH = Low

FLASH

DIAG

exposure

R2

R3

Define

max

time

R4

Define

max

frequency

FLASH

DIAG

R

ETL

R

FRL

VS

EN

C1

NCV7694

GND

output diagnostic pin can be connected directly to the Enable
of the DC/DC converter. In case of fault, the DC/DC
converter is automatically disabled after blanking times.

V

DC / DC

NCV898031

VSTR

DET

GATE

FB

STRING

High LED current

V

<

350 mV

DET

R1

Short DET

pin to Ground

Figure 7. Short to Ground Detection Circuit

When Short to Ground is introduced during
V

STRING

> V

and FLASH is low, the 10 ms blanking

STRth

time eliminate the false faults. When blanking time expires,
the NCV7694 immediately report a fault on the DIAG pin
which leads to the switching OFF the V

STRING

voltage to
protect the LEDs. The output GATE pin remains active. The
device is recovered with next rising edge on the FLASH

input pin. (The next FLASH pulse will not be propagated to
the output, because the DC/DC converter is not activated).

The microprocessor can distinguish between Short to
GND and Open Load during FLASH = Low. If the DIAG pin
remains low during FLASH = Low, the Short to Ground was
detected and it is not recommended to not turn ON the
V

STRING

voltage.

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12

STRING

V

DET

V

V

)

F

–V

STRING

(V

NCV7694

BEHAVIOR OF THE SHORT TO GND

Conditions: VS powered, DC /DC used, EN connected to the DIAG pin

Short to GND

STRth

2.2V

input

FLASH

GATE

V

DIAG

V

FLASH is

propagated

to the output

t

Fault is present

and detected

LEDs are OFF

Figure 8. Timing of the Short to GND Behavior

t

SGBlank

= 1.5 ms activation delay of the DC/DC

DC_EN

V

STRING

is not

t

SGBlank

sufficient, Open

Load isn’t detected

t

DC_EN

t

DC_EN

*) DIAG latched until next FLASH rising edge

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13

Short to VS

NCV7694

VBAT

VDD_MCU

FLASH = High

FLASH

DIAG

R2

20 kW

R3

Define

max

exposure

time

R4

Define

max

frequency

FLASH

DIAG

R

ETL

R

FRL

VS

EN

NCV7694

GND

Figure 9. Short to VSTRING Detection Circuit

When Short Cathode of the LEDs to V

STRING

voltage is
introduced during the FLASH = High and
V

STRING

> V

, the 10 ms blanking time eliminate the

STRth

false faults. When the blanking time expires, the NCV7694
immediately switch OFF the GATE output to protect the
external transistor against high power dissipation. The
DIAG pin will report a fault which will lead to switching
OFF the DC/DC V

voltage if the DIAG pin is

STRING

C1

DC / DC

NCV898031

V

STRING

>V

STRth

V

STRING

VSTR

V

DET

> (V

STRING

– 1.22)V

DET

GATE

GATE − OFF

FB

High
transistor
current

R1

connected to the Enable of the DC/DC converter. The fault
is latched during the FLASH signal is high or until ETL
counter expires. The device will be recovered only with next
falling edge on the FLASH or when the ETL counter is
expired.

The diagnostic is not active when V

STRING

< V

STRth

or

also during FLASH = Low.

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14

NCV7694

Behavior of the Short to V

Conditions: VS powered, DC /DC used, EN connected to the DIAG pin

V

STRth

STRING

V

2.2V

DET

V

input

FLASH

STRING

:

Short to V

STRING

t

DC _E N

GATE

V

DIAG

V

FLASH is

propagated

to the output

t

SCBlank

t

SCBlank

Fault is present

and detected

LED is OFF

Fault is present

GATE is ON during

blanking time only

Figure 10. Timing of the Short to VSTRING Behavior

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15

Overview of the Faults

NCV7694

Normal

Operation

Open

Load

OFF

DET_PULL UP

OFF

DET_PULL UP

OFF ONFLASH =

V

STRING

VSTR

DET

GATE

FB

V

STRING

VSTR

DET

GATE

FB

V

~V

STRING

disabled

V

~ V

STRING

disabled

STRING

R1

STRING

~ 0V

R1

0 V

~ V

STRING

V

STRING >VSTRth

LEDs

are OFF

LEDs

are OFF

ON

ON

V

STRING

VSTR

DET

GATE

FB

V

STRING

VSTR

DET

GATE

FB

V

V

STRING –VF_LEDs

enabled

300mV

V

~ 0V

enabled

~ 0.0mV

STRING

R1

STRING

R1

~ V

STRING

V

STRING >VSTRth

LEDs

are ON

LEDs

are OFF

Short to

Ground

Short to

V

STRING

OFF

DET_PULL UP

OFF

DET_PULL UP

Unrecognizable

V

STRING

VSTR

DET

GATE

disabled

FB

DET < 0.35 V

V

STRING

VSTR

DET

GATE

disabled

FB

Unrecognizable

V

STRING

0V

0.0mV

V

STRING

V

STRING

DET < 0.35 V

or FB < 150

ON

LEDs are

stressed

LED

DC/DC can

disable

High I

V

STRING

R1

Fault is latched

until next rising

DET < 0.35 V

or FB < 150

ON

V

STRING

VSTR

DET

GATE

FB

V

STRING

mV

enabled

~ 0.0mV

mV

V

0V

V

STRING

R1

STRING

LEDs are

stressed

LED

DC/DC can

High I

disable
V

STRING

Same as

Open Load

condition

MOSFET is

stressed

DC/DC can

D(N−MOS)

High P

disable
V

STRING

0V

R1

LEDs

are OFF

DET > (V

VSTR

DET

GATE

FB

STRING

ON

enabled

300 mV

1.22 V)

–

V

STRING

R1

Figure 11. Overview of the Faults

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16

MECHANICAL CASE OUTLINE

PACKAGE DIMENSIONS

1

SCALE 2:1

DFNW10, 3x3, 0.5P

CASE 507AG

ISSUE B

DATE 14 APR 2020

GENERIC

MARKING DIAGRAM*

1

XXXXX
XXXXX
ALYWG

G

XXXXX = Specific Device Code
A = Assembly Location
L = Wafer Lot
Y = Year
W = Work Week
G = Pb−Free Package

(Note: Microdot may be in either location)

*This information is generic. Please refer to

device data sheet for actual part marking.
Pb−Free indicator, “G” or microdot “ G”,
may or may not be present. Some products
may not follow the Generic Marking.

DOCUMENT NUMBER:

DESCRIPTION:

ON Semiconductor and are trademarks of Semiconductor Components Industries, LLC dba ON Semiconductor or its subsidiaries in the United States and/or other countries.
ON Semiconductor reserves the right to make changes without further notice to any products herein. ON Semiconductor makes no warranty, representation or guarantee regarding
the suitability of its products for any particular purpose, nor does ON Semiconductor assume any liability arising out of the application or use of any product or circuit, and specifically
disclaims any and all liability, including without limitation special, consequential or incidental damages. ON Semiconductor does not convey any license under its patent rights nor the
rights of others.

98AON73716G

DFNW10, 3x3, 0.5P

Electronic versions are uncontrolled except when accessed directly from the Document Repository.
Printed versions are uncontrolled except when stamped “CONTROLLED COPY” in red.

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