Preliminary
TS19453
AC/DC Programmable Current WLED Driver
w/PWM Dimming Control
SOP-8
Pin Definition:
1. Rsense
8. Drain
2. Ground
7. Drain
3. PWMD
6. Drain
4. Vdd
5. Ground
General Description
The TS19453 is a PWM high efficiency programmable current LED driver with PWM dimming control IC. It allows
efficient operation of LED strings from voltage source ranging up to 400VDC. It includes an internal high voltage
switching MOSFET controlled with fixed off-time of approximately 12µS.
The LED string is driven at constant current, thus providing constant light output and enhanced reliability. The
output current is internally programmable up to 50mA. The peak current control scheme provides good regulation
of the output current throughout the universal AC line voltage range of 85~264VAC or DC input voltage of
20~400V
Features
●
●
●
●
●
●
Adjust constant output current up to 50mA(typ)
Universal 85~264VAC operation
Over temperature protection with hysteresis
PWM dimming
Fixed off-time buck converter
Internal 475V power MOSFET
Typical Application Circuit
Application
●
●
Decorating LED lighting
LED lamps with AC or DC operation.
Ordering Information
Part No.
TS19453CS RLG
Package
SOP-8
Packing
2.5Kpcs/13” Reel
Note: “G” denote for Halogen Free Product
Absolute Maximum Rating
Parameter
Input Voltage Range
VDD to GND
PMWD, Rsense to GND
Power Dissipation @ T
A
=25ºC
Operating Ambient Temperature
Storage Temperature Range
Thermal Resistance – Junction to Ambient
P
D
T
OPR
T
STG
Rθ
JA
Symbol
V
IN
to GND
V
DD
to GND
Limit
~ +475
~9
~ V
DD
+0.3
Internally Limited
-40 to +85
-65 to +150
160
Unit
V
uA
uA
W
ºC
o
o
C
C/W
Note:
Stresses beyond those listed under ”Absolute Maximum Ratings” may cause permanent damage to the
device. These are stress rating only, and 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 affect device reliability.
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Version: Preliminary
Preliminary
TS19453
AC/DC Programmable Current WLED Driver
w/PWM Dimming Control
Electrical Specifications
(Ta = 25
o
C, V
DRAIN
= 50V, unless otherwise noted)
Function Parameter
Internal Regulator
Internally Regulated Voltage
Drain Supply Voltage
Undervoltage Lockout Threshold
Undervoltage Lockout Hysteresis
Supply Current
Output (Drain)
Breakdown Voltage
On Resistance
MOSFET Saturation current
Current Sense Comparator
Threshold Voltage
Leading edge Blanking delay
Minimum Turn On-Time
Off-Time Generator
Turn On-Time
PWMD
PWMD Input Voltage
PWMD Pull Down Resistance
V
PWMD
R
PWMD
High voltage
Low voltage
VPWMD=5V
2.0
--
100
--
--
--
--
0.8
300
Ω
V
T
OFF
8
12
18
µS
V
TH
T
BLANK
T
ON(min)
Note 1
Note 1,2
0.43
200
--
--
300
--
0.53
400
650
V
nS
nS
V
BR
R
DSON
I
SAT
Note 1
I
DRAIN
=50mA
475
--
100
--
--
150
--
200
--
V
Ω
mA
V
DD
V
DRAIN
UVLO
∆UVLO
I
DD
V
DD
rising
V
DD
falling
V
DD(EXT)
=8.0V
--
20
4.8
--
--
7.5
--
--
200
--
--
400
--
--
500
V
V
V
mV
µA
Symbol
Test Conditions
Min
Typ
Max
Units
Note 1: The specification which apply over the full operating ambient temperature range of -40ºC<T
A
<+85ºC
2: Guaranteed by design
Block Diagram
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Version: Preliminary
Preliminary
TS19453
AC/DC Programmable Current WLED Driver
w/PWM Dimming Control
Function Description
The TS19453 is a PWM peak current controller for controlling a buck converter topology in continuous conduction
mode (CCM). The output current is of converter that can be programmed by a single external resistor (Rsense), for
the purpose of driving a string of LED, an external enable input (PWMD) is provided that can be utilized for PWM
dimming of an LED string.
When the input voltage of 20~400V appears at the Drain pin, the internal high-voltage linear regulator seeks to
maintain a voltage of 7.5VDC at the VDD pin. Until this voltage exceeds the internally programmed under-voltage
threshold, the output switching MOSFET is non-conductive. When the threshold is exceeded, the integrated high-
voltage switch turns on, pulling the Drain low, A 200mV hysteresis is incorporated with the undervoltage
comparator to prevent oscillation.
When the voltage at Rsense exceeds 0.47V(typ), the switch turns off and the Drain output becomes high
impedance, at the same time, a one shot circuit is activated that determines the off-time of the switch.
A “blanking” delay of 300nS is provided that presents false triggering of the current sense comparator due to the
leading edge spike caused by circuit parasitic.
Application Information
The TS19453 is specifically designed for driving multi LED strings. It can be operated from either universal AC line
range of 85~264VAC or 20~400VDC, and drives up to tens of high brightness LEDs. All LEDs can be run in series
and this device regulates at constant current, yielding uniform illumination.
Selecting L1 and D1
There is a certain trade-off to be considered between optimal sizing of the output inductor L1 and the tolerated
output current ripple. The required value of L1 is inversely proportional to the ripple current
∆I
O
in it.
L1 = (V
O
x T
OFF
) /
∆I
O
V
O
is the forward voltage of the LED string. T
OFF
is the off-time of the TS19453. The output current in the LED string
(I
O
) is calculated as:
I
O
= (Vth / Rsense) – (∆I
O
/ 2)
Where I
TH
is the current sense comparator threshold, and Rsense is the current sense resistor. The ripple current
introduces a peak-to-average error in the output current setting that needs to be accounted for. Due to constant off-
time control technique used in the TS19453, the ripple current is independent of the input AC or DC line voltage
variation. Therefore, the output current will remain unaffected by the varying input voltage.
Adding a filter capacitor across the LED string can reduce the output current ripple even further, thus permitting a
reduced value of L1. However, one must keep in mind that the peak-to-average current error is affected by the
variation of T
OFF
. Therefore, the initial output current accuracy might be sacrificed at large ripple current in L1.
Another important aspect of designing an LED driver with TS19453 is related to certain parasitic elements of the
circuit, including distributed coil capacitance of L1, junction capacitance and reverse recover of the rectifier diode
D1, capacitance of the PCB traces C
PCB
and output capacitance C
DRAIN
of the controller itself. These parasitic
elements affect the efficiency of the switching converter and could potentially cause false triggering of the current
sense comparator if not properly managed. Minimizing these parasitic is essential for efficient and reliable
operation.
Coil capacitance of inductors is typically provided in the manufacturer’s data books either directly or in terms of the
self-resonant frequency (SRF).
SRF = 1 / (2π√(L * C
L
))
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Version: Preliminary
Preliminary
TS19453
AC/DC Programmable Current WLED Driver
w/PWM Dimming Control
Application Information (Continue)
L is the inductance value, and C
L
is the coil capacitance. Charging and discharging this capacitance every
switching cycle causes high-current spikes in the LED string. Therefore, connecting a small capacitor C
O
(~100nF)
is recommended to bypass these spikes.
Using an ultra-fast rectifier diode for D1 is recommended to achieve high efficiency and reduce the risk of false
triggering of the current sense comparator. Using diodes with shorter reverse recovery time t
rr
and lower junction
capacitance C
J
achieves better performance. The reverse voltage rating V
R
of the diode must be greater than the
maximum input voltage of LED lamps.
The total parasitic capacitance present at the Drain pin of the TS19453 can be calculated as:
C
P
= C
DRAIN
+ C
PCB
+ CL + C
J
When the switching MOSFET turns on, the capacitance C
P
is discharged into the Drain pin of the IC. The discharge
current is limited to about 50mA typically. However, it may become lower at increased junction temperature. The
duration of the leading edge current spike can be estimated as:
T
PSIKE
= ((V
IN
x C
P
) / (I
SAT
)) + t
rr
In order to avoid false trigger of the current sense comparator, C
P
must be minimized in accordance with the
following expression.
C
P
=< (Isat * ( T
BLANK(min)
- t
rr
)) / Vin(max)
When T
BLANK(min)
is the minimum blanking time of 200nS, and Vin(max) is the maximum instantaneous input voltage.
Estimating Power Loss
Discharging the parasitic capacitance C
P
in the the Drain output of TS19453 is responsible for the bulk of the
switching power loss. It can be estimated using as:
P
SWITCH
= ((C
P
* V
IN
/ 2 ) + (V
IN
* I
SAT
* t
rr
)) * F
S
F
S
is the switching frequency and is the saturated Drain current of TS19453, the switching loss is the greatest at
the maximum input voltage.
Disregarding the voltage drop at TS19453 and D1, the switching frequency is given as
2
F
S
= (V
IN
- V
OUT
) / (V
IN
* T
OFF
)
When the TS19453 is powered from full wave rectified AC input, the swithching power loss can be estimated as:
P
SWITCH
= 1 / (2 * T
OFF
) * ((V
AC
* C
P
+ 2 * I
SAT
* t
rr
) * (V
AC
- V
OUT
)))
When the TS19453 is powered from DC input voltage, conduction power loss can be estimated as:
P
COND
= (D * I
OUT
* R
ON
) + I
DD
* V
IN
* (1 – D)
2
EMI Filter
As with all off-line converters, selecting an input filter is critical to obtaining good EMI. A switching side capacitor,
albeit of small value, is necessary in order to ensure low impedance to the high frequency switching currents of the
converter. As a rule of thumb, this capacitor should be approximately 0.1~0.2µF/W of LED output power.
4/7
Version: Preliminary
Preliminary
TS19453
AC/DC Programmable Current WLED Driver
w/PWM Dimming Control
Typical Application Circuit
Typical Application Circuit for Universal 85~264VAC LED Lamps Driver (Non-Isolation)
15pcs LED (VLED=49.5V), LED current 50mA
5/7
Version: Preliminary
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