TS19452
AC/DC WLED Driver with Internal MOSFET
Universal Switch Mode
SOP-8
Pin assignment:
1. Drain
8. Ground
2. Drain
7. Ground
3. Drain
6. Ground
4. Vdd
5. Ground
General Description
The TS19452 is a PWM high efficiency LED driver control IC. It allows efficient operation of LED strings from
voltage source ranging up to 450VDC. 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 fixed at 100mA. 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
●
●
●
●
●
Constant output current at 100mA(typ)
Universal 85~264VAC operation
Fixed off-time buck converter
Internal 475V power MOSFET
Low inductance value at 4.7mH (typ)
Typical Application Circuit
Application
●
●
Decorating LED lighting
LED lamps with AC or DC operation.
Ordering Information
Part No.
TS19452CS RLG
Package
SOP-8
Packing
2.5Kpcs / 13” Reel
Note:
“G” denote for Halogen Free Product
Absolute Maximum Rating
Parameter
Input Voltage Range
Supply Current
Power Dissipation @ T
A
=25ºC
Operating Ambient Temperature
Storage Temperature Range
Junction Temperature Range
Symbol
V
IN
to GND
I
DD
P
D
T
OPR
T
STG
T
J
Limit
~ +475
400
2500
-40 to +85
-65 to +150
-40 to +150
Unit
V
uA
mW
ºC
o
o
o
C
C
Thermal Resistance – Junction to Ambient
Rθ
JA
65
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.
1/7
Version: A12
TS19452
AC/DC WLED Driver with Internal MOSFET
Universal Switch Mode
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
Output Capacitance
MOSFET Saturation current
Current Sense Comparator
Threshold Current
Leading edge Blanking delay
Minimum Turn On-Time
Off-Time Generator
Turn On-Time
T
OFF
8
12
18
µS
I
TH
T
BLANK
T
ON(MIN)
Note 1
Note 1,2
90
200
--
--
300
--
110
400
650
mA
nS
nS
V
BR
R
DSON
C
DRAIN
I
SAT
Note 1
I
DRAIN
=100mA
V
DRAIN
=400V
550
--
--
--
--
--
1.0
--
--
100
5.0
120
V
Ω
pF
mA
V
DD
V
DRAIN
UVLO
∆UVLO
I
DD
V
DD
rising
V
DD
falling
V
DD(EXT)
=8.5V, V
DRAIN
=40V
--
20
5
--
--
7.5
--
--
200
--
--
450
--
--
400
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
2/7
Version: A12
TS19452
AC/DC WLED Driver with Internal MOSFET
Universal Switch Mode
Function Description
The TS19452 is a PWM peak current controller for controlling a buck converter topology in continuous conduction
mode (CCM). The output current is internally preset at 100mA
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 MOSFET turns
on. The input current begins to flow into the Drain pin. Hysteresis in provided in the under-voltage comparator to
prevent oscillation.
When the input current exceeds the internal preset level, a current sense comparator resets an RS flip-flop, and the
MOSFE turns off, At the same time, a one-shot circuit is activated that determines the duration of the off-state
(12µS typ.) As soon as this time is over, the flip-flop sets again. The new switching cycle begins.
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 TS19452 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 TS19452. The output current in the LED string
(I
O
) is calculated as:
I
O
= I
H
– (∆I
O
/ 2)
Where I
TH
is the current sense comparator threshold. 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
TS19452, 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.
According 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 TS19452 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 of the TS19452.
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 · CL))
3/7
Version: A12
TS19452
AC/DC WLED Driver with Internal MOSFET
Universal Switch Mode
Application Information (Continue)
Where 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 TS19452 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 150mA 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
r
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: A12
TS19452
AC/DC WLED Driver with Internal MOSFET
Universal Switch Mode
Electrical Characteristics Curve
Figure 1. Switch-Off Transition
Ch1: V
DRAIN
, Ch3: I
DRAIN
Figure 2. Switch-On Transition
Ch1: V
DRAIN
, Ch3: I
DRAIN
Figure 3. Lead Edge Spike
Ch1: V
DRAIN
, Ch3: I
DRAIN
5/7
Version: A12
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