LED Controller. LX27901 Datasheet

LX27901 Controller. Datasheet pdf. Equivalent

LX27901 Datasheet
Recommendation LX27901 Datasheet
Part LX27901
Description High Performance LED Controller
Feature LX27901; WWW.Microsemi .COM LX27901 ® High Performance LED Controller TM PRODUCTION DATASHEET DESCRIPTION .
Manufacture Microsemi Corporation
Datasheet
Download LX27901 Datasheet




Microsemi Corporation LX27901
LX27901
® High Performance LED Controller
TM
PRODUCTION DATASHEET
DESCRIPTION
KEY FEATURES
The LX27901 is a high performance LED Direct PWM input dimming operation can
controller optimized for LCD-TV and other be realized by inputting a dimming pulse
multi-lamp LCD display systems and train to DIM pin directly.
provides a cost competitive solution for off- The ACU_BRITE algorithm allows the DC
PFC LED drive applications.
to DC converter to be turned off when the
The controller provides a pair of PWM digital dimming operation is at off state to
drive signals with adequate capacity to drive eliminate no-load power losses. The
a half bridge or other double ended DC to controller also provides a proprietary
DC converter circuit with the addition of synchronous regulation function to allow the
simple external circuitry to provide safety user to control the LED current and dimming
isolation.
operation from an un-regulated switching
The device includes a regulated 5.25V power supply source to minimize the number
output (VDD) activated by the ENABLE of power conversion stages and the
input working from the VIN input voltage of associated losses and component costs. In
up to 27V. VDD is capable of providing synchronous regulation mode, AOUT and
5mA source current to external circuitry BOUT form a pair of drive signals to control
while supplying the on chip driver stage and the LED string pairs in AC current mode,
the control circuitry.
and COUT provides another option to
The controller allows the user to utilize control the LED in DC current mode.
two different converter drive schemes, LLC A versatile set of system monitoring and
resonant or PWM control mode, selected by protection functions are incorporated in the
the signal level at ENABLE pin, to best fit a LX27901 design to provide reliable
wide spectrum of application needs.
protection of the device and the system.
In addition, a proprietary ACU_BRITE
algorithm is incorporated in the dimming
control operation to allow the user to
adaptively adjust the PWM dimming duty to
achieve accurate brightness control over a
wide dimming duty cycle range while
maintaining the highest operating efficiency.
Three input pins, ISNS, VSNS and
UVS/SYN are assigned to support the
regulation and protection sense feedback
needs over wide range of application
configurations. Likewise a dedicated fault
indication pin allows the user to generate a
direct fault report to the system and
configure addition protection features with
The LX27901 supports analog LED current simple external circuits.
control utilizing the BRTA pin as the analog
LED current setting function.
The device is available in 16 lead SOIC
surface mount package in the industrial
temperature range.
IMPORTANT: For the most current data, consult MICROSEMI’s website: http://www.microsemi.com
Three Selectable Drive Modes to
Support Wide Range of Topologies
Optimized Solution for Off PFC LED
Drive Applications
0.8A Source & Sink Drive Capacity
On Chip 5.25V Regulator
Direct Connection to Input Voltage
up to 27V
ACU_BRITE Algorithm to Provide
Accurate Brightness Control at
Highest Operating Efficiency Over
Wide Dimming Duty Range
User Selectable Dimming Mode
Control
Synchronous Regulation Function
to Minimize Power Conversion
Stage
Accurate LED Current Matching In
Combination With Microsemi’s Non-
dissipative Balancing Technology
Robust Operation at Open and
Short LED Conditions
Compensated External and Internal
PWM Dimming Operation
Dedicated Fault Indication
LED Current and Voltage
Monitoring
RoHS Compliant & Halogen Free
APPLICATIONS
LCD LED Backlight TV
LCD LED Backlight Monitors
Other LED Backlight Systems
PACKAGE ORDER INFO
TA (C)
D
Plastic SOIC 16 Pin
RoHS Compliant / Pb-free
-40 to +85
LX27901ID
Note: Available in Tape & Reel. Append the letters “TR” to the part number.
(i.e. LX27901ID-TR)
THERMAL DATA
JA = 82.2 C/W
THERMAL RESISTANCE-JUNCTION TO AMBIENT
Junction Temperature Calculation: TJ = TA + (PD x JA).
The JA numbers are guidelines for the thermal
performance of the device/pc-board system. All of the
above assume no ambient airflow. JA number above is
with 4-layer pcb board.
Copyright 2011
Rev. 1.1
Microsemi
Analog Mixed Signal Group
11861 Western Avenue, Garden Grove, CA. 92841, 714-898-8121, Fax: 714-893-2570
Page 1



Microsemi Corporation LX27901
LX27901
® High Performance LED Controller
TM
PRODUCTION DATASHEET
AABSOLUTE MAXIMUM RATINGS
Supply Input Voltage, VIN ...............................................................................0.3V to 36V
Signal Outputs, VDD, AOUT, BOUT, C_OUT..............................................-0.3V to 6.5V
Signal Inputs, C_R, BRTA ..................................................................-0.3V to VDD+0.3V
Signal Inputs, ENABLE, DIM, ISNS, VSNS, UVS/SYN ...................-0.3V to VDD+0.3V
Signal Outputs COMP, SST/BCOM, FAULT ...............................................-0.3V to VDD
Maximum Junction Temperature ............................................................................... 150°C
Storage Temperature Range.........................................................................-65C to 150C
Peak Package Solder Reflow Temperature (40 seconds maximum exposure)........... 260°C
Lead Temperature. (Soldering 10 seconds)................................................................ 300°C
Notes: Exceeding these ratings could cause damage to the device. All voltages are with respect to
GND. Currents are positive into, negative out of specified terminal. These are stress ratings
only and functional operation of the device at these or any other conditions beyond those
indicated under “Recommended Operating Conditions” are not implied. Exposure to
Absolute Maximum Ratingsfor extended periods may affect device reliability.
PACKAGE PIN OUT
VIN
ENABLE
C_R
BRTA
DIM
SST/
BCOM
FAULT
UVS/
SYN
VDD
AOUT
GND
BOUT
C_OUT
COMP
ISNS
VSNS
LX27901ID
D PACKAGE
(Top View)
RoHS / Pb-free Matte Tin Pin Finish
ELECTRICAL CHARACTERISTICS
Unless otherwise listed, the following specifications apply over the operating ambient temperature of -40°C < Temp < 85°C, and VIN = 7.5V to 27V, except
where otherwise noted and the following test conditions: VIN = 12V, CC_R = 330pF, RC_R= 15k
Parameters
Symbol Test Conditions/Comments
MIN TYP MAX Units
Power
Controller Input Voltage
Controller Operating Voltage
Power Supply Input Current
VIN
VDD
IIN
1µF bypass cap on VDD pin,
IVDD = 0 to 5mA
AOUT, BOUT = no load, VDD = no load
7.5 27
5.0 5.25 5.5
7 10
V
V
mA
Sleep Mode Current
IDDSLEEP VIN = 24V, VENABLE < 0.8V
200 400
µA
VDD Off Voltage
ENABLE < 0.8V
0.1 V
Enable
ENABLE On
ENH
1.7 V
Shut Down
LLC Resonant Mode
Threshold
PWM Switching Mode
Threshold
Synchronous LED Drive Mode
Threshold
Input High Current
ENL
VLLCTH
VPWMTH
VSYN
ENIIH
LLC resonant drive mode, VDD =
5.25V0.25V
PWM switching drive mode, VDD =
5.25V0.25V
Synchronous LED drive mode, VDD =
5.25V0.25V
ENABLE = 2V
0.8 V
2 2.8 V
3.2 3.5 3.7
V
4.3
VDD
V
10 µA
Input Low Current
Under Voltage Lockout
ENIIL
0V < VENABLE < 0.8V
5 µA
VDD Startup Threshold
VDDUVLOR Rising Threshold.
4.3 4.6 4.9
V
VDD UVLO Threshold
VDDUVLOF Falling Threshold.
3.95 4.25 4.55
V
VDD UVLO Hysteresis
VDDUVLOH
0.4 V
NOTE: The LX27901 operates at LLC mode when the Enable voltage 1.7V @ VIN=12V
Copyright 2011
Rev. 1.1
Microsemi
Analog Mixed Signal Group
11861 Western Avenue, Garden Grove, CA. 92841, 714-898-8121, Fax: 714-893-2570
Page 2



Microsemi Corporation LX27901
LX27901
® High Performance LED Controller
TM
PRODUCTION DATASHEET
ELECTRICAL CHARACTERISTICS
Unless otherwise listed, the following specifications apply over the operating ambient temperature of -40°C < Temp < 85°C, and VIN = 7.5V to 27V, except
where otherwise noted and the following test conditions: VIN = 12V, CC_R = 330pF, RC_R= 15k
Parameters
Symbol Test Conditions/Comments
MIN TYP MAX Units
Output
Output Resistance
Output Resistance
RSINK
RSOURCE
ISINK, AOUT and BOUT, TA = 25°C
ISOURCE, AOUT and BOUT, TA = 25°C
56
56
Dead Time
OUTDT TA = 25°C, at full duty
270 350 430
ns
C_OUT Output Resistance
RC_OUT Source and sink
10 20
Switching Frequency Oscillator
Switching Frequency
Tolerance
LLC Frequency Control
Current Source
OSCIN
TA = 25°C, Frequency of AOUT, BOUT in PWM
mode, CC_R=330pF, RC_R = 15K.
138
150
162
kHz
VENABLE < 2.8V
0 160
µA
Ramp Valley Voltage
OSCVV
0.5 V
Ramp Peak Voltage
Synchronization Range
LED Dimming Control
ISNS Reference
ISNS Linear Input Range
BRTA Input Range
Pre-Amplifier Gain
OSCPV
Ratio of UVS/SYN input over C_R oscillator
free run frequency
2.5
1.05
V
3 Ratio
ISNSREF
KPRAMP
TA = 25°C, input, Corresponds to 2V after
4.75X internal amplifier.
Linear operation range for internal circuit
4.75X of ISNS signal. Input outside the range
is clamped at upper or lower limit internally.
414.6 421 427.4
600
0.5 2.0
4.75
mV
mV
V
Error Amp Output Capacity
Source and Sink
100 µA
DIM Input Voltage Range
VDIM Effective for duty from 0 to 100%
0.5 2.0
Voltage level of FAULT pin, in ACU_BRITE
PWM Dimming Mode Control
Threshold
VPDMODETH
PWM dimming mode when below threshold; in
conventional PWM dimming mode when
2.8
3.0
3.2
above threshold.
Fault Monitoring and Protection
V
V
VSNS Threshold
VCOMP Voltage
UVS/SYN Threshold
UVS/SYN Input Range
ISNS Fault Threshold
VSNSTH
1.8 2.0 2.2
V
Vcomp2 when the Aout present @ Vsns=0V,
VVCOMP_diff
ISNS=0.15V; Vcomp1 when the Aout disabled
@ Vsns=3V, ISNS=0V; TA = 25°C
VCOMP Voltage=Vcomp2 Vcomp1
0.1
UVS/SYNTH
Fault when below the threshold, positive and
negative input
0.33 0.4 0.45
VUVS/SYN
Functional operation range, positive and
negative input
-0.5
4
V
V
V
VISNSTH Fault when below the threshold
90 110 130 mV
Over Current Threshold
OCTH
Upper threshold for ISNS input
580 630 680 mV
Short Circuit Threshold
SCTH
Upper threshold for ISNS input
940 1000 1060 mV
Copyright 2011
Rev. 1.1
Microsemi
Analog Mixed Signal Group
11861 Western Avenue, Garden Grove, CA. 92841, 714-898-8121, Fax: 714-893-2570
Page 3







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