NCV7694MW0R2G [ONSEMI]
Safety Controller for Infra-Red LED Illumination to Complement the Image Sensor for Automotive Applications;
| 型号： | NCV7694MW0R2G |
| 厂家： | 
ONSEMI |
| 描述： | Safety Controller for Infra-Red LED Illumination to Complement the Image Sensor for Automotive Applications |
| 文件： | 总18页 (文件大小：276K) |
| 中文： | 中文翻译 | 下载： | 下载PDF数据表文档文件 |
Safety Controller for
Infra-Red LED Illumination
to Complement the Image
Sensor for Automotive
Applications
NCV7694
www.onsemi.com
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.
1
The NCV7694 driver features prevents the IR LEDs from being on
too long due to an inappropriate exposure time or being turned on too
DFNW10, 3x3, 0.5P
CASE 507AG
frequently using external resistors. The value of the R
resistor
ETL
defines the maximum T time of the emitted light intensity and the
ON
MARKING DIAGRAM
value of the R
resistor defines the maximum frequency of the
FRL
FLASH signal from the image sensor.
NV76
94−0
ALYW
S
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
NV7694−0
A
L
Y
W
S
= Specific Device Code
= Assembly Location
= Wafer Lot
= Year
= Work Week
= Pb−Free Package
• Constant Current Output for LED String Drive
• FLASH Input Pin
PIN CONNECTIONS
• Open LED Diagnostic Detection
VSTRING
1
2
3
4
5
10
9
VS
• 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
DIAG
DET
GATE
FB
FLASH
RETL
8
7
RFRL
GND
6
Top View
• Detection and Protection Against Under−Voltage and over
Temperature
ORDERING INFORMATION
• AEC−Q100 Qualified and PPAP Capable
• ASIL−A safety design, ISO26262 compliant
†
Device
NCV7694MW0R2G
Package
Shipping
• 10 Pin Packaging
DFN10
2500 / Tape &
Reel
• Wettable Flank Package for Enhanced Optical Inspection
(Pb−Free)
• These are Pb−Free Devices
†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.
Applications
• In−Cabin Monitoring Sensor
• Infrared Illumination for Automotive Cameras
• Machine Vision Systems
• Surveillance Systems
© Semiconductor Components Industries, LLC, 2020
1
Publication Order Number:
February, 2021 − Rev. 2
NCV7694/D
NCV7694
VS
VBAT
Supply for MCU and Image Sensor
CSUPPLY
VDD_MCU
VDD_AR
VDD_MCU
R2
VDD_MCU
VS
VDD_AR
20k
REMC1
1 kW
VSTR
DET
Data
interface
REMC2
1 kW
Image Sensor
AR 0135
FLASH
FLASH
Micro−
controller /
DSP
Q1
R1
REMC3
200 W
REMC4
750 W
GATE
FB
DIAG
RETL
NCV7694
GND
Diag detection
Note1: 4x optional
EMC shield resistors
ZD
R3
GND
RFRL
Define max
R4
exposure time
GND
Define max
frequency
Note2: Optional Zener diode
Figure 1. Application Diagram − Powered Directly from Battery
VBAT
DC /DC
Supply for MCU and Image Sensor
VString
CSUPPLY
EN
C1
NCV898031
VDD_MCU
VDD_AR
VDD_MCU
R2
VDD_MCU
VS
VDD_AR
20k
REMC1
1 kW
VSTR
Data
interface
REMC2
1 kW
Image Sensor
AR 0135
DET
FLASH
FLASH
Micro−
controller /
DSP
REMC3
200 W
GATE
FB
DIAG
RETL
NCV7694
REMC4
750 W
GND
Diag detection
Note1: 4x optional
EMC shield resistors
ZD
R3
R1
GND
RFRL
Define max
exposure time
R4
GND
Define max
frequency
Note2: Optional Zener diode
for Mosfet Gate protection
Figure 2. Application Diagram − using DC/DC
RECOMMENDED EXTERNAL COMPONENTS FOR THE APPLICATION DIAGRAM
Component
C1
Function
Min
Typ
100
100
20
Max
Unit
nF
mW
kW
kW
kW
W
Decoupling capacitor
FB current sense resistor
DIAG pull−up resistor
R1
R2
R3
Resistor for Exposure Time Limitation
Resistor for Frame Rate Limitation
0.8
0.8
15
15
R4
REMC1
REMC2
REMC3
REMC4
Optional EMC shield resistor for VSTR pin
Optional EMC shield resistor for DET pin
Optional EMC shield resistor for GATE pin
Optional EMC shield resistor for FB pin
1000
1000
200
W
W
750
W
(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.
Figure 1 shows an example of the typical output drive
configuration. The current through the external LEDs is
equal to
ILEDs = VFB / R1
(Note 2) Optional Zener diode may be used if the VS
Where:
supply is higher than V voltage of the external transistor.
GS
• V is internal feedback reference = 300 mV
FB
In case of Open Load on the LEDs, the GATE voltage will
go high, the Zener diode will limit the maximum voltage
during eventual Open Load condition.
• R is feedback resistor which set the current
1
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2
NCV7694
Block Diagram
VS
Supply
monitoring
V
V
SVth
STRING
1.22 V
SC = V − 1.22 V
FLASH
th
str
Short Circuit
LED − Vstr
R
FLASH
DET
Short Circuit
LED − GND
Controlling,
Monitoring,
Filtering &
decoding
DIAG
350 mV
V
SGth
GATE
R
ETL
Exposure
R
Time Limit
GATE
R
K
ETL
ETL
=
=
t
t
ETL
R
FRL
K
FRL
300mV
RTL
FRL
f
= 1/ t
FRL
FB
V
FBref
Open Load
R
FRL
Frame Rate
150 mV
Limit
V
OLth
GND
Figure 3. Simplified Block Diagram
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3
NCV7694
Timing Characteristics
e.g.: 45 Hz = 22 .2 ms period
Double frequency pulse
Typical pulse
Too long pulse
Typical pulse
Short pulse
FLASH
ET threhsold
Exposure Time
Counter
t
ETL
t
FRL
FR threshold
Frame Rate
Counter
LED output
Rest of the pulse
Typical pulse
Short pulse
Driver is activated with
next rising edge of
FLASH pulse
Second pulse is cut off
because “FR” counter is
not reach the threshold
is cut−OFF because “ET”
counter exceed the
threshold
Figure 4. Simplified Internal Timing Characteristic of the Internal ETL, FRL Counter
Safety Feature Behavior
The period of the internals counters can be adjusted by
external resistors.
External Resistor Approach
Total tolerance of the maximum T or maximum Frame
ON
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.
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.
Ǹ
2
2
+ Ǹ
aTOTAL
adevice ) aresistor + 13.02 ) 12 + 13.04 %
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4
NCV7694
PIN FUNCTION DESCRIPTION
10−pin DFN10
Package
Pin #
Label
VS
Description
1
2
Supply voltage of the device
Diagnostic output
DIAG
FLASH
3
Logic input for flash exposure time
4
R
R
External resistor defines maximum Exposure Time Limit
External resistor defines maximum Frame Rate Limit
Ground
ETL
FRL
5
6
GND
FB
7
Feedback reference input 300 mV.
Gate drive for external mosfet
8
GATE
DET
9
LED short detection input
10
V
Short circuit reference voltage
STRING
MAXIMUM RATINGS
Symbol
Parameter
Continuous supply voltage
Min.
Max.
Unit
Vmax_VS
−0.3
−
+40
+40
V
V
Transient Voltage (t < 500 ms, “load dump”)
Vmax_FLASH
Vmax_GATE
Low Voltage Input pin
−0.3
−0.3
−0.3
−0.3
−0.3
−0.3
+3.6
+VS
+3.6
+3.6
+40
V
V
V
V
V
V
Output voltage (during Open Load condition)
DC voltage on Resistors
Vmax_R , R
ETL
FRL
Vmax_FB
Low Voltage Input pin
Vmax_DIAG
Open Drain pin
Vmax_DET,
High Voltage Input pin
+40
V
STRING
Tjmax
Junction Temperature, T
−40
+125
°C
J
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.
ATTRIBUTES
Parameer
Value
Unit
ESD Capability (Note 2)
HBM (Human Body Model)
≥
≥
≥
4.0
1.0
200
kV
kV
V
CDM (Charge Device Model)
MM (Machine Model)
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
62.5
5.5
2.7
°C/W
°C/W
°C/W
q
JA
− Junction to Board, R
q
JB
− Junction to Case (Top), R
q
JC
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
= 4.99 kW, R
=1.96 kW, 4 V < V < 28 V, Transistor = NVTFS5C478NL, LED = SFH 4725AS,
STRING
ETL
FRL
R1 = 100 mW, −40°C ≤ T ≤ 125°C, unless otherwise specified)
J
Characteristic
Symbol
Conditions
Min.
Typ.
Max.
Unit
GENERAL
Supply Voltage
VS_OP
VSUV
Parametric operation
VS rising
7
4.0
150
−
−
28
5.0
550
6.0
V
V
Supply Under−Voltage Lockout
Supply Under−Voltage hysteresis
Supply Current in normal condition
4.5
300
4.0
VSUVhys
I_VS
mV
mA
VS = 14 V,
FLASH = High,
I
, I
subtracted
FRL ETL
VS = 14V,
FLASH = Low,
, I subtracted
−
−
3.8
4.0
6.0
6.0
mA
mA
I
FRL ETL
Supply Current in Fault condition
I_VSerr
VS = 14 V,
FLASH = High,
Open Load condition,
FRL ETL
I
, I
subtracted
Thermal Shutdown (TSD)
Thermal Hysteresis
FB DRIVER
130
150
15
170
°C
°C
−
−
FB Regulation reference
Gate ON voltage
V
Under Voltage Lockout < VS
FB = 220 mV,
DET = 1.0 V
270
4.5
300
−
330
−
mV
V
FBref
V
GATE
Propagation Delay
t
50% criterion
−
−
−
8
15
15
4
μs
μs
μs
ON
FLASH rising – FB ON
Propagation Delay
FLASH falling – FB OFF
t
50% criterion
6.6
1.4
OFF
FLASH propagation Delay Delta
t
|(Falling time) –
(Rising Time)|
pd_delta
50% criterion
Output pull−down resistance
R
5
30
100
kW
GATE
FLASH INPUT PIN
Input High Threshold
Input Low Threshold
Input pull−down resistance
V
V
1.3
−
30
1.2
1.15
120
−
1.1
190
V
V
kW
inH
inL
R
FLASH
PROGRAMMING
R
Bias voltage
V
R
−
1.0
−
V
VETL
1.0
RETL
ETL
ETL
IETL
+
+
+ 200.4 mA
4990
ETL resistor operation range
external resistor value operation
range
0.8
−
15
kW
ETL
for R
for R
= 800 W => t = 320 ms;
ETL
ETL
ETL
= 15 kW => t
= 6 ms
ETL
Maximum T time (typ)
T
Derived from R
and K ;
ETL(typ)
−
−
−
6.0
ms
ON
ONmax
ETL
valid for R
= 15 kW
ETL
ETL multiplication
K
2.5
−
kW/s
RETL
tETL
ETL
KETL
tETL
+
RETL
KETL
4.99
+
+
+ 1.996 ms
2.5
K
ETL
tolerance
tol
ETL
Tolerance of Exposure Time Limit
13.0
%
Overcurrent protection R
I
Short to ground
1.3
−
−
mA
ETL
ETL_lim
Resistor detection for
R
< 750 W
ETL
Open Load protection R
I
Open Load detection
Resistor detection for
ETL
−
−
57.5
mA
ETL
ETL_open
R
> 17.5 kW
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6
NCV7694
ELECTRICAL CHARACTERISTICS
(7 V < VS < 28 V, R
= 4.99 kW, R
=1.96 kW, 4 V < V < 28 V, Transistor = NVTFS5C478NL, LED = SFH 4725AS,
STRING
ETL
FRL
R1 = 100 mW, −40°C ≤ T ≤ 125°C, unless otherwise specified)
J
Characteristic
PROGRAMMING
Symbol
Conditions
Min.
Typ.
Max.
Unit
FRL resistor
operation range
R
external resistor value operation
range
0.8
−
15
kW
FRL
for R
= 1 kW => f
=100 Hz
FRL
FRL
(10 ms)
for R
= 10 kW => f
=10Hz
FRL
FRL
(100 ms)
Maximum FLASH Frequency (typ)
FRL multiplication
f
Derived from R
and K
;
−
−
−
125
Hz
max
FRL
FRL(typ)
valid for R
= 800 W
FRL
K
−
RFRL
tFRL
FRL
KFRL
+
0.1
RFRL
KFRL
1.96
tFRL
fFRL
+
+
+ 19.6 ms
0.1
1
tFRL
1
+
+
+ (51 Hz)
0.0196
K
FRL
tolerance
tol
FRL
Tolerance of Frame Rate Limit
13.0
%
Overcurrent protection R
I
Short to ground
1.3
−
−
mA
FRL
FRL_lim
Resistor detection for
R
< 750 W
FRL
Open Load protection R
I
Open Load detection
Resistor detection for
FRL
−
−
57.5
mA
FRL
FRL_open
R
> 17.5 kW
OPEN LOAD / SHORT TO GND
Open Load Detection Threshold (FB pin)
Open Load
Blanking Time
V
FLASH = High
130
10
150
22
170
35
mV
ms
OLth
t
OLBlank
Short to GND Detection Threshold
(DET pin)
V
FLASH = Low
300
5
350
10
400
15
mV
SGth
Short to GND
Blanking Time
t
ms
SGBlank
SHORT CIRCUIT
Short to V
Detection Threshold
V
SCth
FLASH = High
V
ING
1.5
V
ING
1.22
V
ING
0.9
V
STRING
STR
STR
STR
−
−
−
Short Circuit Blanking Time
t
5
10
15
ms
SCBlank
Input pull−up resistor on DET pin
R
Pull−up to V
30
120
190
kW
DETPull−up
STRING
DIAG OUTPUT
V
diagnostic activation threshold
V
V voltage
STRING
2.0
2.2
0.2
2.4
0.4
V
V
STRING
STRth
Output low level
V
Fault is present,
= 0.33 mA
−
OUTL
I
DIAG
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7
NCV7694
PINS DESCRIPTION
FLASH
Open Load condition, if the when FB voltage will be below
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
FLASH time which can be propagated to the output is 6 ms
and minimum T time, which will can be set, is typically
8 ms. The NCV7694 can be used as companion device for
60 Hz camera sensors in full FLASH T range or 120 Hz
with limited T range.
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.
and R
resistors, the maximum T
ETL
FRL ON
OFF
GATE
The NCV7694 can drive MOSFET transistors with
minimum GATE voltage of 4.5 V. The preferred mosfet
transistor is NVTFS5C478NL.
ON
ON
DIAG
RETL and RFRL
To reduce thermal retina hazard and thermal injury risk of
the cornea, the safety turn−off function is implemented.
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
LEDs. Diagnostic pin can be connected to the Enable pin of
the DC/DC converter. The output V 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
or Short to Ground of the
STRING
External R
and R
resistor defines maximum
ETL
FRL
exposure time and maximum frame rate. The maximum
times are calculated using resistor values of the R and
STRING
ETL
R
FRL
resistors divided by K
or K
coefficients. If the
FRL
ETL
FLASH pulse is permanently HIGH, the output pulse is
being activated only after FRL timer expire and during the
allowed ETL time period.
Open Load and Short circuit detections of the R , R
ETL FRL
timing resistors are reported on the DIAG pin as well as the
Thermal Shutdown Flag and Under Voltage status on the VS
supply.
Short and Open on the RETL and RFRL
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
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
(0.35 V) to V
SGth
SVth
(V
– 1.22 V). Below 0.35 V the device will detect
STRING
Short to ground and above V
will detect Short LEDs to V
minus 1.22 V the device
STRING
.
STRING
In case of DET pin is disconnected, device will go into
fault because internal pull−up to V is implemented.
Short to ground can be detected only when output is not
activated.
VSTRING
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.
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
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NCV7694
DETAILED OPERATING DESCRIPTION
Under Voltage Lockout
short filter time the driver is switched off and fault on the
DIAG pin is reported.
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.
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.
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
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NCV7694
Open Load Detection
VBAT
VDD_MCU
VSTRING
DC /DC
EN
C1
NCV898031
R2
20 kW
VS
VSTR
VSTRING > VSTRth
FLASH = High
DET
FLASH
DIAG
FLASH
GATE
DIAG
NCV7694
VFB
<
150 mV
FB
R
R
ETL
FRL
R3
R1
Define
max
exposure
time
R4
Define
GND
max
frequency
Figure 5. Open Load Detection Circuit
When Open Load fault is introduced during
FLASH = High and V > V , the 22 ms blanking
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.
approximately 2 ms to re−activate the DC/DC V
STRING
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.
STRING
STRth
Diagnostic is not active when V
< V
. The first
STRING
STRth
If EN pin of the DC/DC converter is connected to the
DIAG output, the Open Load causes switching OFF the
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.
V
STRING
voltage. The DIAG pin is recovered as soon as
FLASH pin goes low or ELT counter expired. It will take
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10
NCV7694
OPEN LOAD BEHAVIOR
Conditions: VS powered, DC /DC used, EN connected to the DIAG pin
Open Load present
V
STRth
2.2 V
tOLBlank
t DC_EN
tDC_EN
tDC_EN
= 1.5 ms activation delay of the DC/DC
FLASH is
Fault is present
and detected
LED is OFF
V
is not
STRING
propagated
to the output
sufficient, Open
Load isn’t detected
Figure 6. Timing of the Open Load Behavior
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NCV7694
Short to Ground
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.
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
VBAT
VSTRING
VDD_MCU
EN
DC / DC
NCV898031
C1
High LED current
R2
20 kW
VS
VSTR
FLASH = Low
V DET
<
350 mV
DET
FLASH
FLASH
GATE
FB
DIAG
DIAG
RETL
NCV7694
R3
Define
max
R1
RFRL
exposure
time
R4
Define
max
GND
frequency
Figure 7. Short to Ground Detection Circuit
When Short to Ground is introduced during
> V and FLASH is low, the 10 ms blanking
time eliminate the false faults. When blanking time expires,
the NCV7694 immediately report a fault on the DIAG pin
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
STRth
which leads to the switching OFF the V
voltage to
STRING
protect the LEDs. The output GATE pin remains active. The
device is recovered with next rising edge on the FLASH
V
STRING
voltage.
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12
NCV7694
BEHAVIOR OF THE SHORT TO GND
Conditions: VS powered, DC /DC used, EN connected to the DIAG pin
Short to GND
V
STRth
2.2V
tSGBlank
tSGBlank
tDC_EN
tDC_EN
t
DC_EN = 1.5 ms activation delay of the DC/DC
FLASH is
propagated
to the output
Fault is present
and detected
VSTRING is not
sufficient, Open
Load isn’t detected
LEDs are OFF
*) DIAG latched until next FLASH rising edge
Figure 8. Timing of the Short to GND Behavior
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13
NCV7694
Short to VS
VBAT
VDD_MCU
DC / DC
VSTRING
EN
NCV898031
C1
R2
20 kW
VS
VSTRING > VSTRth
VSTR
FLASH = High
V
DET > (VSTRING– 1.22)V
FLASH
FLASH
DET
High
transistor
current
GATE
DIAG
DIAG
RETL
NCV7694
GATE − OFF
FB
R3
R1
Define
max
RFRL
exposure
time
R4
GND
Define
max
frequency
Figure 9. Short to VSTRING Detection Circuit
When Short Cathode of the LEDs to V
introduced during the FLASH
voltage is
High and
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.
STRING
=
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
The diagnostic is not active when V
also during FLASH = Low.
< V
or
STRING
STRth
OFF the DC/DC V
voltage if the DIAG pin is
STRING
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14
NCV7694
Behavior of the Short to VSTRING
:
Conditions: VS powered, DC /DC used, EN connected to the DIAG pin
Short to VSTRING
tDC _EN
V
STRth
2.2V
tSCBlank
tSCBlank
FLASH is
propagated
to the output
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
NCV7694
Overview of the Faults
FLASH =
OFF
VSTRING
ON
VSTRING
VSTRING >VSTRth
VSTRING >VSTRth
VSTRING
VSTRING
OFF
ON
LEDs
are OFF
LEDs
are ON
VSTR
DET
VSTR
DET
VSTRING –VF_LEDs
~VSTRING
DET_PULL UP
GATE
FB
enabled
300mV
GATE
FB
disabled
Normal
Operation
0 V
R1
R1
VSTRING
VSTRING
VSTRING
VSTRING
OFF
ON
LEDs
are OFF
LEDs
are OFF
VSTR
DET
VSTR
DET
~ VSTRING
~ VSTRING
Open
Load
~ 0V
~ VSTRING
DET_PULL UP
GATE
FB
enabled
~ 0.0mV
GATE
FB
disabled
~ 0V
R1
R1
DET < 0.35 V
or FB < 150mV
Unrecognizable
VSTRING
VSTRING
VSTRING
VSTRING
OFF
ON
LEDs are
stressed
DC/DC can
disable
LEDs are
stressed
DC/DC can
disable
VSTR
DET
VSTR
DET
Short to
Ground
VSTRING
0V
VSTRING
0V
DET_PULL UP
GATE
FB
enabled
GATE
FB
disabled
~ 0.0mV
R1
0.0mV
R1
Fault is latched
until next rising
Same as
Open Load
condition
DET < 0.35 V
DET < 0.35 V
or FB < 150
mV
VSTRING
VSTRING
VSTRING
VSTRING
OFF
ON
MOSFET is
stressed
DC/DC can
disable
LEDs
are OFF
VSTR
DET
VSTR
DET
Short to
VSTRING
VSTRING
VSTRING
VSTRING
DET_PULL UP
GATE
FB
enabled
GATE
FB
disabled
0V
R1
300 mV
R1
ON
DET > (VSTRING 1.22 V)
–
Unrecognizable
Figure 11. Overview of the Faults
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16
MECHANICAL CASE OUTLINE
PACKAGE DIMENSIONS
DFNW10, 3x3, 0.5P
CASE 507AG
ISSUE B
1
DATE 14 APR 2020
SCALE 2:1
GENERIC
MARKING DIAGRAM*
1
XXXXX
XXXXX
ALYWG
G
XXXXX = Specific Device Code
A
L
= Assembly Location
= Wafer Lot
Y
W
G
= Year
= Work Week
= 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.
Electronic versions are uncontrolled except when accessed directly from the Document Repository.
Printed versions are uncontrolled except when stamped “CONTROLLED COPY” in red.
DOCUMENT NUMBER:
DESCRIPTION:
98AON73716G
DFNW10, 3x3, 0.5P
PAGE 1 OF 1
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相关型号：
NCV7701DWG
IC STEPPER MOTOR CONTROLLER, 5 A, PDSO20, LEAD FREE, SOIC-20, Motion Control Electronics
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