TS19460_D15

TS19460
Taiwan Semiconductor
AC/DC WLED Driver with Average-Mode
Constant Current Control
DESCRIPTION
FEATURES
The TS19460 is an average current mode control LED
driver IC operating in a constant off-time mode. It
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Fast average current controller
Programmable constant off-time switching
greatly improves accuracy, line and load regulation of
the LED current without any need for loop
compensation or high-side current sensing. The output
LED current accuracy is at ±5%, and it is equipped
with current limit comparator for hiccup mode output
short circuit protection.
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Linear and PWM dimming capability
Requires few external components for operation
Output short circuit protection with skip mode
Pin –compatible with TS19450CS
The TS19460 can be powered from an 8V~450V
supply. A PWM dimming input is provided that
accepts an external control TTL compatible signal.
The output current can be programmed by an
APPLICATION
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internal 250mV reference, or controlled externally
through a 0~1.5V dimming input. The TS19460 is
ideally suited for buck LED drivers and is requires
only free external components (apart from the power
stage) to produce a controlled LED current making it
an ideal solution for low cost LED drivers.
DC/DC or AC/DC LED driver applications
RGB backlighting LED driver
Back lighting of flat panel displays
General purpose constant current source
Signage and decorative LED lighting
LED street lighting
SOP-8
Pin Definition:
1. VIN
8. RT
2. CS
7. LD
3. GND
6. VDD
4. Gate
5. PWMD
Notes: Moisture sensitivity level: level 3. Per J-STD-020
TYPICAL APPLICATION CIRCUIT
Document Number: DS_P0000188
1
Version: D15
TS19460
Taiwan Semiconductor
ABSOLUTE MAXIMUM RATINGS (TA = 25°C unless otherwise specified) (Note 1)
PARAMETER
SYMBOL
LIMIT
UNIT
Input Voltage Range
VIN to GND
-0.5 ~ +470
V
Internal Regulated Voltage
VDD to GND
12
V
-0.3 ~ (VDD+0.3)
V
PD
650
mW
TA
-65 to +150
o
TJ
-40 to +150
o
SYMBOL
LIMIT
RθJA
128
CS, LD, PWMD, Gate, RT to GND
Continuous Power Dissipation
(Note 2)
Storage Temperature Range
Junction Temperature Range
THERMAL PERFORMANCE
C
C
(Note 3)
PARAMETER
Thermal Resistance – Junction to Ambient
UNIT
o
C/W
ELECTRICAL SPECIFICATIONS (TA= 25oC, VIN= 12V, VLD=PWM=VDD, unless otherwise noted)
PARAMETER
SYMBOL
CONDITION
(Note 4)
MIN
TYP
MAX
UNIT
8.0
--
450
V
--
0.5
1.0
mA
7.25
7.5
7.75
V
0
--
1.0
V
0
--
100
mV
Input
DC Input Voltage Range
VINDC
DC input voltage
Shut-down Mode Supply Current
IINSD
Pin PWMD to GND
Internal Regulator
VIN=8V, IDD(EXT)=0,
Internally Regulated Voltage
VDD
500pF at Gate,
RT=226kΩ
VIN=8~450V, IDD(EXT)=0
Line Regulation of VDD
Load Regulation of VDD
Undervoltage Lockout Threshold
∆VDDLine
∆VDDLoad
500pF at Gate,
RT=226kΩ
IDD(EXT)= 0 ~ 1mA
500pF at Gate,
RT=226kΩ
UVLO
VIN rising
6.45
6.7
6.95
V
Undervoltage Lockout
Hysteresis
∆UVLO
VIN falling
--
500
--
mV
Maximum Input Current
IIN (MAX)
VIN=8V
3.5
--
--
mA
Dimming
PWMD Input Low Voltage
VENL
VIN=8V~450V
--
--
0.8
V
PWMD Input High Voltage
VENH
VIN=8V~450V
2.0
--
--
V
PWMD Pull-down resistance at
PWMD
REN
VPWMD=5V
50
100
150
kΩ
Document Number: DS_P0000188
2
Version: D15
TS19460
Taiwan Semiconductor
ELECTRICAL SPECIFICATIONS (TA= 25oC, VIN= 12V, VLD=PWM=VDD, unless otherwise noted)
PARAMETER
SYMBOL
CONDITION
MIN
TYP
MAX
UNIT
Average Current Sense Logic
Current Sense Reference
Voltage
VCS
238
250
262
mV
LD to Current Sense Ratio
Av (LD)
--
0.18
--
mV
LD input Voltage Shutdown
VLD(OFF)
VLD falling
--
150
--
mV
LD input Voltage Enable
∆VLD(OFF)
VLD rising
--
200
--
mV
150
--
280
ns
--
--
1
μS
32
--
48
8
--
12
Current Sense Blanking Interval
TBLANK
Minimum On-Time
TON(min)
VCS= VCS + 30mV
RT=1MΩ
μS
Off Time
TOFF
Max. Steady-State Duty Cycle
DMAX
75
--
--
%
VCS
410
--
470
mV
--
--
150
ns
330
--
460
μS
--
--
430
μS
RT=226kΩ
Short Circuit Protection
Hiccup Threshold Voltage
Current Limit Delay CS to Gate
TDELAY
VCS= VCS + 30mV
Short Circuit Hiccup Time
THICCUP
Minimum On-Time (Short Circuit)
TON(min)
VCS= VDD
ISOURCE
VGATE=0V, VDD=7.5V
165
--
--
mA
Gate Sinking Current
ISINK
VGATE=VDD, VDD=7.5V
165
--
--
mA
Gate Output Rise Time
TRISE
--
30
50
ns
Gate Output Fall Time
TFALL
--
30
50
ns
Gate Driver
Gate Sourcing Current
CGATE=500pF,
VDD=7.5V
CGATE=500pF,
VDD=7.5V
Note:
1. Stresses listed as the above “Absolute Maximum Ratings” may cause permanent damage to the device. These
are for stress ratings. Functional operation of the device at these or any other conditions beyond those
indicated in the operational sections of the specifications is not implied. Exposure to absolute maximum rating
conditions for extended periods may remain possibility to affect device reliability.
2. Limited by package power dissipation, whichever is lower.
3. Thermal Resistance is specified with the component mounted on a low effective thermal conductivity test board
in free air at TA=25°C.
4. Denotes the specifications which apply over the full operating ambient temperature range of -40ºC<TA<+125ºC.
Document Number: DS_P0000188
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Version: D15
TS19460
Taiwan Semiconductor
ORDERING INFORMATION
PART NO.
TS19460CS RLG
PACKAGE
PACKING
SOP-8
2,500pcs / 13” Reel
Note:
1. Compliant to RoHS Directive 2011/65/EU and in accordance to WEEE 2002/96/EC.
2. Halogen-free according to IEC 61249-2-21 definition.
Document Number: DS_P0000188
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Version: D15
TS19460
Taiwan Semiconductor
FUNCTION BLOCK DIAGRAM
PIN DESCRIPTION
PIN NO.
NAME
FUNCTION
1
VIN
This pin is the input of 8V~450V linear regulator
2
CS
This pin is the current sense pin used to sense the MOSFET current by means
of an external sense resistor.
3
GND
Ground return for all internal circuitry. This pin must be electrically connected
to the ground of the power train.
4
GATE
This pin is the output GATE driver for an external N-CH Power MOSFET
5
PWMD
This is the PWM dimming input of the IC. When this pin is pulled to GND, the
Gate Driver is turned off. When the pin is pulled high, the GATE driver
operates normally.
This is the power supply pin for all internal circuits.
6
VDD
7
LD
long as the voltage at the pin is less than 1.5V, The Gate output is disable
when LD voltage <150mV(typ.) and recovery when LD voltage >200mV (typ.)
8
RT
A resistor is connected between RT and GND to program the Gate off-time.
It must be bypassed with a low ESR capacitor to GND (≥0.1µF)
This pin is the linear dimming input and sets the current sense threshold as
Document Number: DS_P0000188
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Version: D15
TS19460
Taiwan Semiconductor
APPLICATION INFORMATION
The TS19460 is optimized to drive buck LED drivers using average current mode control. This method of control
enables fairly accurate LED current control without the need for high side current sensing or the design of any
closed loop controllers. The IC uses very few external components and enables both linear and PWM dimming of
the LED current.
A resistor connected to the RT pin programs the off-time. Constant off-time control average current mode is used
for stability and to improve the LED current regulation over a wide range of input voltages.
The current through the switching MOSFET source is averaged and used to give constant-current feedback. This
current is detected from a sense resistor at the CS pin, the feedback operates in a fast open-loop mode, there is no
compensation required, the output current is programmed as
ILED = 0.25V / RCS
When the Voltage at the LD input >1.5V, otherwise
ILED = ( VLD * 0.181 ) / RCS
When application to design the inductor witching ripple current in it is 40% of average peak to peak, full load
current, the inductance can be calculated as follow:
LOUT = ( VOUT(max) * T OFF ) / ( 0.4 * IOUT )
The duty cycle range of current control feedback is limited to duty <75%, A reduction in the LED current string
voltage is greater than 75% of input voltage.
Reducing the output LED voltage is below VOUT(MIN) = VIN * D(MIN), where D(MIN) = 1uS / (TOFF + 1uS), may also
result in the loss of regulation of LED current. This condition will cause an increase in the LED current and can be
possible to trip the short circuit protection comparator.
The short circuit protection comparator trips when the voltage at CS exceeds 0.44V, the Gate off time ( THICCUP =
400μs) is generated to prevent stair-casing of inductor current and potentially its saturation due to insufficient
output voltage.
The leading edge blanking delay is provided at CS to prevent false triggering of current feedback and short circuit
protection.
Input Voltage Regulator
The TS19460 can be powered directly from its VIN pin and can work from 8.0VDC~450VDC at its VIN pin. When a
voltage is applied at the VIN pin, the TS19460 maintains a constant 7.5V at the VDD pin. This voltage is used to
power the IC and any external resistor dividers needed to control the IC. The VDD pin must be bypassed by a low
ESR capacitor to provide a low impedance path for the high frequency current of the output GATE driver. The
TS19460 can be also operated by supplying a voltage at the VDD pin greater than the internally regulated voltage.
Please note that this external voltage at the VDD pin should not exceed 12V.
Although the VIN pin of the TS19460 is rated up to 450V, the actual maximum voltage that can be applied is limited
by the power dissipation in the IC. For example, if an SOP-8 (junction to ambient thermal resistance RθJA = 128°C/
W) TS19460 draws about IIN = 2.0mA from the VIN pin, and has a maximum allowable temperature rise of the
junction temperature limited to about the maximum voltage at the VIN pin would be:
VIN(MAX) = ( T J(MAX) – T A ) / ( RθJA * IIN ) = 390V
Document Number: DS_P0000188
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Version: D15
TS19460
Taiwan Semiconductor
APPLICATION INFORMATION (CONTINUE)
In these cases, to operate the TS19460 from higher input voltages, a Zener diode can be added in series with the
VIN pin to divert some of the power loss from the TS19460 to the Zener diode. In the above example, using a 100V
Zener diode will allow the circuit to easily work up to 490V.
The input current drawn from the VIN pin is a sum of the 1.0mA current drawn by the internal circuit and the current
drawn by the GATE driver (which in turn depends on the switching frequency and the GATE charge of the external.
IIN ≈ 1mA + QG x fS
In the above equation, f S is the switching frequency and QG is the GATE charge of the external MOSFET (which
can be obtained from the datasheet of the MOSFET).
Oscillator
The oscillator in the TS19460 is controlled by a single resistor connected at the RT pin. The equation governing the
off-time of the GATE output is given by:
T OFF(μS) = ( RT (kΩ) / 25 ) + 0.3
*within the range of 30kΩ ≤ RT ≤ 1MΩ
Linear Dimming
The Linear Dimming pin is used to control the LED current, when voltage at LD is fall below 1.5V, the internal
reference voltage (250mV) to the constant current feedback become over ridden by VLD * 0.181, and the current in
the inductor remain continuous, the LED current is given by ILED = ( VLD * 0.181 ) / RCS, The Gate output is disable
when LD voltage <150mV(typ.) and recovery when LD voltage >200mV (typ.)
The Linear Dimming input could also be used for mixed-mode dimming to expand the dimming ratio, in this kind of
application condition, the pulse-width modulated signal of a measured amplitude below 1.5V should be applied at
LD.
PWM Dimming
PWM Dimming can be achieved by driving the PWMD pin with a square wave signal. The rising and falling edges
are limited by current slew rate in inductor, the first switching cycle is terminated upon reaching the level (250mV)
at CS, the circuit is further reaching its steady state within 3~5 switching cycle regardless of the switching
frequency.
Document Number: DS_P0000188
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Version: D15
TS19460
Taiwan Semiconductor
PACKAGE OUTLINE DIMENSIONS (Unit: Millimeters)
SOP-8
SUGGESTED PAD LAYOUT (Unit: Millimeters)
Marking Diagram
Y = Year Code
M = Month Code for Halogen Free Product
O =Jan P =Feb Q =Mar R =Apr
S =May T =Jun U =Jul
V =Aug
W =Sep X =Oct
Y =Nov Z =Dec
L = Lot Code (1~9, A~Z)
Document Number: DS_P0000188
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Version: D15
TS19460
Taiwan Semiconductor
Notice
Specifications of the products displayed herein are subject to change without notice. TSC or anyone on its behalf,
assumes no responsibility or liability for any errors or inaccuracies.
Information contained herein is intended to provide a product description only. No license, express or implied, to
any intellectual property rights is granted by this document. Except as provided in TSC’s terms and conditions of
sale for such products, TSC assumes no liability whatsoever, and disclaims any express or implied warranty,
relating to sale and/or use of TSC products including liability or warranties relating to fitness for a particular purpose,
merchantability, or infringement of any patent, copyright, or other intellectual property right.
The products shown herein are not designed for use in medical, life-saving, or life-sustaining applications.
Customers using or selling these products for use in such applications do so at their own risk and agree to fully
indemnify TSC for any damages resulting from such improper use or sale.
Document Number: DS_P0000188
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Version: D15