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PDF BD18378EFV-M Data sheet ( Hoja de datos )
| Número de pieza | BD18378EFV-M | |
| Descripción | Advanced 12 Channel Constant Current LED Driver IC | |
| Fabricantes | ROHM Semiconductor | |
| Logotipo |  |
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Advanced 12 Channel
Constant Current LED Driver IC
BD18378EFV-M
General Description
The BD18378EFV-M is a serial input controlled constant
current LED driver with 8 V output rating. 6 bit current
calibration is available for each output while a selected
PWM input performs dimming on the corresponding
output. The BD18378EFV-M is able to perform diagnostic
(open / short / temperature) checks to detect LED failure
and over temperature on chip. Fault detection is
performed also during LED deactivated state. The
settings of all internal registers can be read out to verify
written information at any time.
Features
AEC-Q100 Qualified (Note1)
Current capability: 50mA per output channel.
4-line SPI Control.
External resistor current setting.
Limp Home capability.
PWM dimming 0.2-99.2% at 200Hz
Diagnostic of all PWM inputs.
Programmable output mapping to each PWM input.
6 Bit LED brightness adjustment on each channel.
Diagnostic output on LED OPEN and SHORT for
each channel during PWM on & off time.
True LED voltage measurement.
Over Temperature Protection and Thermal
Feedback.
Open Drain Fault indicator.
Read-back of all register settings.
Outputs can be connected in parallel to achieve
more than 50mA into the load.
Slew Rate limited switching reduces
radiated Noise (EMI).
Daisy chain compatible.
(Note1: Operating Temperature Grade 2)
Typical Application Circuit Diagram
Key Specifications
Input voltage range:
Output voltage range:
Output Current range:
Output Current accuracy
Maximum clock frequency:
Operating current:
Operating temperature range:
3V to 5.5V
0.5V to 8V
10mA to 50mA
3.5%
1.25MHz
4mA (Typ.)
- 40°C to +105°C
Package
HTSSOP-B28
L(Typ.) x W(Typ.) x H(Max.)
9.70mm x 6.40mm x 1.00mm
Applications
Automotive illumination & ambient light
Consumer electronics illumination
LEDs
8V max
RP
CLED
VLED
5.5V max
VCC
VCC ERR
0 1 2 3 4 5 6 7 8 9 10 11 SENSE
CHANNEL
CIN BD18378EFV-M
Heat Sink
Noisy
ground line
PGND
Quiet
ground line
AGND
IREF
01
PWM
2 34
5
SDI CLK SDO LATCH
REXT
to Controller
Figure 1. Typical application diagram
○Product structure：Silicon monolithic integrated circuit
.www.rohm.co
©m 2015 ROHM Co., Ltd. All rights reserved.
TSZ22111・14・001
○This product is not designed protection against radioactive rays
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TSZ02201-0W1W0C500020-1-2
04. Dec. 2015 Rev.004
1 page  
BD18378EFV-M
Protection circuitry and diagnostic
o LED Short Detection
A short event is detected when the voltage across the LED falls below the short detection threshold
VSCth. The SHORT detection current which is flowing during LED active (PWM =”LOW”), will cause a typical
output current offset of 20µA. After a detected LED short event, the corresponding bit of the Gen_SHORT
detection register and the ANY_SHORT_OPEN_FLAG from the STATUS register remain high until cleared by
the controller. The SHORT detection is also performed, when the LED is not activated, using small sink
currents for small time intervals (20us) to avoid LED flicker. In order for the detection to be available at
non-activated LED state the PWM duty cycle must be <99.2% at a frequency of 200Hz.
o LED Open Detection
During an open event the output device will be fully ON, pulling VDx low. An open event is detected when
voltage VDx at the output pin falls below VOth. The OPEN detection current, Ipulldown which is flowing during LED
active (PWM = “LOW”), will cause a typical output current offset of 20µA. After a LED open event has been
detected the corresponding bit of the Gen_OPEN detection register and ANY_SHORT_OPEN_FLAG from the
STATUS register remain high until cleared by the controller. The OPEN detection is also performed, when the
LED is not activated, using small sink currents for small time intervals (20us) to avoid LED flicker. In order for
the detection to be available at non-activated LED state the PWM duty cycle must be <99.2% at a frequency of
200Hz.
Note: In order to distinguish between diagnostics (LED Short Detection and LED Open Detection) at ON and
OFF, the corresponding detection must be enabled and corresponding state of the channel must be checked
(enabled/disabled).
o Short to Ground Detection
The chip can perform output short to ground diagnosis during non-activated LED state. After LED short and
open at channel off diagnosis, a short to ground can be also detected. In order for the detection to be available
at non-activated LED state the PWM duty cycle must be <99.2% at a frequency of 200Hz.
The diagnostic is activated or deactivated by the EN_SHORT_TO_GND register.
After an output short to ground has been detected the corresponding bit of the SHORT_TO_GND detection
register and ANY_SHORT_TO_GND_FLAG from the STATUS register remain high until cleared by the
controller.
Note: In case both the Open Detection and Short to GND Detection are active at the same time and the voltage
VDx at the output pin falls below VSGth also the corresponding bit of the Gen_OPEN detection register and
ANY_SHORT_OPEN_FLAG from the STATUS register remain high until cleared by the controller.
EN_CHANNEL
CHANNEL ACTIVE
CHANNEL NOT ACTIVE
PWM
PWM ACTIVE PWM NOT ACTIVE
Diagnostic
SHORT/OPEN PULL_UP@ON
@ON
SHORT/
PULL_UP@OFF OPEN SHORT
@OFF TO GND
tdiag_off
20us
Figure 4. Diagnostic diagram
o IREF Fault Detection (Limp Home functionality)
The chip can perform IREF short and open diagnostic on the external resistor. In case of an error the
REXT_FAULT flag is set and latched and an internal current reference is used to set a typical output current of
IREF_LH. If the fault condition is removed the chip can be reset to the normal operating state by a POR event.
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m© 2015 ROHM Co., Ltd. All rights reserved.
TSZ22111・15・001
5/26
TSZ02201-0W1W0C500020-1-2
04. Dec. 2015 Rev.004
5 Page 
BD18378EFV-M
1=visible
0=not visible
u=unchanged
WRITE_LOCK command:
Register Name
UNLOCK
Address
Data Code<7:0>
69 x x x EN_ERR PWM_MAP EN_CH CAL
Comments
All DIAG
Lock
o Code:
default “11111”=unlocked
1=lock
0=don’t touch
x=don’t care
o EN_ERR locks EN_ERR_PIN register
o CAL locks CALx registers
o EN_CH locks EN_CHANNEL register
o PWM MAP locks PWM_MAPx registers
o All DIAG locks EN_SHORT@ON, EN_OPEN@ON, EN_SHORT@OFF, EN_OPEN@OFF,
EN_SHORT_TO_GND, EN_PULL_UP@ON, EN_PULL_UP@OFF, EN_WLS registers
WRITE_UNLOCK command & READ_UNLOCK command:
Register Name
UNLOCK
UNLOCK
Address
6A
A9
x x x EN_ERR
u u u EN_ERR
Data Code<7:0>
PWM_MAP EN_CH
PWM_MAP EN_CH
CAL
CAL
Comments
All DIAG unlock reg.
All DIAG Read Unlock
o Code for write:
Code for read: default “11111”=unlocked
1=unlock
0=don’t touch
x=don’t care
1=unlocked
0=locked
u=unchanged
o EN_ERR unlocks EN_ERR_PIN register
o CAL unlocks CALx registers
o EN_CH unlocks EN_CHANNEL register
o PWM MAP unlocks PWM_MAPx registers
o All DIAG unlocks EN_SHORT@ON, EN_OPEN@ON, EN_SHORT@OFF, EN_OPEN@OFF,
EN_SHORT_TO_GND, EN_PULL_UP@ON, EN_PULL_UP@OFF, EN_WLS registers
RESET_STATUS command:
Register Name Address
Data Code<7:0>
Comments
RESET_STATUS
6B
o Code:
1=reset
0=don’t touch
x=don’t care
SHORT
x x to
GND
ANY
SHORT
OPEN
WLS
PWM_OK
TSD
POR
Clear status
flags
(Note1: TSD clears bot TSD130 and TSD180 flags)
(Note2: After clearing the flags with the RESET_STATUS command the registers will immediately reflect
the actual status)
SOFTWARE_POR command:
Register Name Address
Data Code<7:0>
Comments
SOFTWARE_POR
6C
1
0
1
0
0
0
0
1
Resets all registers and sets
POR flag HIGH
Default Register setting:
Register
CALIBRATION<5:0>
(of all channels)
Default values after POR
<000000>
Comments
Set all currents to min value
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m© 2015 ROHM Co., Ltd. All rights reserved.
TSZ22111・15・001
11/26
TSZ02201-0W1W0C500020-1-2
04. Dec. 2015 Rev.004
11 Page | ||
| Páginas | Total 30 Páginas | |
| PDF Descargar | [ Datasheet BD18378EFV-M.PDF ] | |
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