Holtek HT7L4811 Non-isolation buck led lighting driver with active pfc Datasheet

HT7L4811
Non-isolation Buck LED
Lighting Driver with Active PFC
Features
General Description
• Tiny package SOT23-6
The HT7L4811 is a non-isolation buck PWM controller
for LED lighting applications. The device has a fully
integrated PFC circuit which operates in a boundary
conduction mode (BCM) to achieve high power factor
values. With good control over external MOSFETs, the
device can easily meet exacting LED current and high
power factor requirements.
• Non-isolation buck topology
• Low BOM Cost
• Wide AC input range – from 85VAC to 265VAC
• High Power Factor of >0.9 without additional
circuitry
• Accurate constant current (< ±3%)
The HT7L4811 provides several protection functions,
which include VCC Under Voltage Lockout (UVLO),
Over Current Protection (OCP), Output LED
String Open Protection, Output LED String Short
Protection, VCC Over Voltage Protection (OVP) and
Leading-Edge Blanking (LEB) for current sensing.
Additionally and to ensure system reliability, the
device includes a fully integrated thermal protection
function. To protect the external power MOSFET
from being damaged by a supply over voltage, the
device DRV pin voltage is clamped to about 17V.
• Low start-up current which reduces power
dissipation
• Full protection functions for enhanced safety
♦♦ Gate driver output voltage clamp
♦♦ VCC over voltage protection (VCC OVP)
♦♦ VCC under-voltage lockout with hysteresis
(VCC UVLO)
♦♦ Output LED string over current protection
♦♦ Output LED string short protection
♦♦ Output LED string open protection
♦♦ On-chip over temperature protection (OTP)
The high level of functional integration minimises the
external component count giving major advantages
in terms of cost and circuit board area. The device is
supplied in a SOT23-6 package.
Applications
• General illumination
• E26/27, T5/T8 LED Lamp
• Other LED Lighting Applications
Rev. 1.30
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HT7L4811
Block Diagram
DRV
VCC
Reference
& Bias
UVLO
Driver
Min
Off Time
VCC OVP
ZCD
ZCD
Comparator
Logic
Control
ZCD OVP
OTP
Starter
OCP
CS
PWM
Generator
EA
0.2V
LEB
COMP
GND
Pin Assignment
SOT23-6
COMP CS
ZCD
L4811
VCC
Top View
GND DRV
Pin Description
Pin No.
Symbol
1
VCC
Power supply pin
Description
2
GND
Ground pin
3
DRV
Gate drive output for driving external power MOSFETs
4
ZCD
5
CS
Current sense pin. A resistor is connected to sense the MOSFET current.
6
COMP
Loop compensation pin. A capacitor is placed between COMP and GND.
Rev. 1.30
Zero-current detect pin
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HT7L4811
Absolute Maximum Ratings
Input voltage to CS pin.............................. -0.3V to 6V
Maximum current at ZCD pin.................3mA (source),
3mA (sink)
Output voltage at COMP pin..................... -0.3V to 6V
Maximum operating junction temperature.......... 150°C
VCC supply voltage................................. -0.3V to 33V
Storage temperature range................... -55°C to 150°C
Note: These are stress ratings only. Stresses exceeding the range specified under ″Absolute Maximum Ratings″
may cause substantial damage to the device. Functional operation of this device at other conditions beyond
those listed in the specification is not implied and prolonged exposure to extreme conditions may affect
device reliability.
Recommended Operating Ranges
Operating junction temperature...........−40°C to 125°C
VCC supply voltage....................................17V to 25V
Electrical Characteristics
Symbol
Parameter
VCC=18V, Ta=25°C
Test Condition
Min
Typ
Max
Unit
Power Supply (VCC Pin)
VCCON
UVLOON
—
—
18
—
V
VCCOFF
UVLOOFF
—
—
10
—
V
VCCHYS
UVLO Hysteresis
—
7
—
—
V
VOVP
VCC OVP Trip Point
—
26
29
32
V
—
10
20
μA
ISTART
Start-up Current
Before turn-on,
@ VCC = UVLOON - 1V
IQ
Quiescent Current
No switching
—
0.6
1
mA
ICC
Operating Current
@ 70kHz, Co=1nF
—
1.8
2.5
mA
194
200
206
mV
Error Amplifier
VFB
Feedback Reference Voltage
Ta = 25°C
Current Sense Comparator
tLEB
Leading Edge Blanking Time
—
—
400
—
ns
VCL
Current Limit Threshold
—
—
1.3
—
V
Over Current Trip Point
—
—
0.9
—
V
Over Current Release Point
—
—
0.2
—
V
V
VOCP
Zero Current Detector
VZCDH
Upper Clamp Voltage
IZCD = 300μA
—
3
—
VZCDL
Lower Clamp Voltage
IZCD = -2.5mA
—
-0.2
—
V
VZCDA
Positive-Going Edge
—
—
1.5
—
V
VZCDT
Negative-Going Edge
—
—
1
—
V
IOVP
OVP Current on ZCD pin
—
270
300
330
μA
tB_OVP
Blanking Time for OVP Detection
—
—
1
—
μs
tSTART
Start Timer Period
—
—
40
—
μs
tOFF
Minimum Off Time
—
—
4
—
μs
—
—
150
—
°C
Starter
Over Temperature Protection
OTP
Rev. 1.30
Over Temperature Trip Point
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HT7L4811
Symbol
Parameter
Test Condition
Min
Typ
Max
Unit
85
—
ns
Gate Driver
tR
Rising Time
CLOAD=1nF, 10%~90%
—
tF
Falling Time
CLOAD=1nF, 10%~90%
—
50
—
ns
ISource
Source Current
—
—
220
—
mA
ISink
Sink Current
—
—
250
—
mA
VG_CLAMP
Gate Clamp Voltage
@ VCC = 25V
—
16
19.5
V
Typical Performance Characteristics
start up current (uA)
16
14
12
10
8
6
4
-40
-20
0
20
40
60
80
100
120
temperature (℃)
Figure 1. Start-Up Current vs. Temperature
operating current (mA)
2
1.95
1.9
1.85
1.8
1.75
1.7
1.65
1.6
-40
-20
0
20
40
60
temperature (℃)
80
100
120
Figure 2. Operation Current vs. Temperature
19
UVLO_on(V)
18.6
18.2
17.8
17.4
17
-40
-20
0
20
40
60
80
100
120
temperature (℃)
Figure 3. UVLO_on vs. Temperature
Rev. 1.30
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HT7L4811
11
UVLO_off(V)
10.6
10.2
9.8
9.4
9
-40
-20
0
20
40
60
temperature (℃)
80
100
120
100
120
Figure 4. UVLO_off vs. Temperature
201
VFB (mV)
200.5
200
199.5
199
198.5
198
-40
-20
0
20
40
60
80
temperature (℃)
Figure 5. VFB vs. Temperature
163.00
Iout (mA)
162.50
162.00
161.50
161.00
90Vac
115Vac
180Vac
240Vac
160.50
160.00
9S
10S
11S
AC Input (VAC)
100Vac
135Vac
220Vac
265Vac
12S
13S
Figure 6. Iout vs. LED(s) Regulation in E27 Bulb
Rev. 1.30
5
June 26, 2015
HT7L4811
163.00
Iout (mA)
162.50
162.00
161.50
161.00
9S (162mA)
11S (162mA)
13S (162mA)
160.50
160.00
90
100
115
135
180
10S (162mA)
12S (162mA)
220
240
265
AC Input (VAC)
Figure 7. Iout vs. Wide AC Voltage in E27(8W, 13S / 162mA) Bulb
89.0%
88.0%
Efficiency
87.0%
86.0%
85.0%
84.0%
83.0%
9S (162mA)
11S (162mA)
13S (162mA)
82.0%
81.0%
10S (162mA)
12S (162mA)
80.0%
90
100
115
135
180
AC Input (VAC)
220
240
265
Power Factor (PF)
Figure 8. Efficiency vs. Wide AC Voltage in E27(8W, 13S / 162mA) Bulb
1.000
0.980
0.960
0.940
0.920
0.900
0.880
0.860
0.840
0.820
0.800
9S (162mA)
11S (162mA)
13S (162mA)
90
100
115
10S (162mA)
12S (162mA)
135
180
AC Input (VAC)
220
240
265
Iout(mA)
Figure 9. Power Factor (PF) vs. Wide AC Voltage in E27(8W, 13S / 162mA) Bulb
420
419
418
417
416
415
414
413
412
411
410
90Vac
115Vac
180Vac
240Vac
LED 10S
LED 11S
100Vac
135Vac
220Vac
265Vac
LED 12S
LED 13S
LED 14S
LED(S)
Figure 10. Iout vs. LED(s) Regulation in T8 Tube
Rev. 1.30
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June 26, 2015
HT7L4811
420
419
418
Iout (mA)
417
416
415
414
413
412
LED 10S
LED 11S
411
LED 13S
LED 14S
LED 12S
410
90
100
115
135
180
220
240
265
AC input (Vac)
Figure 11. Iout vs. Wide AC Voltage in T8 (18W, 12S / 425mA*) Tube
89
Efficiency (%)
88
87
86
85
84
83
82
10S,414mA
12S,414mA
14S,414mA
81
11S,414mA
13S,414mA
80
90
100
115
135
180
220
240
265
AC input (Vac)
Figure 12. Efficiency vs. Wide AC Voltage in T8(18W, 12S / 425mA) Tube
1.000
0.980
0.960
PF
0.940
0.920
0.900
10S,414mA
12S,414mA
14S,414mA
0.880
0.860
11S,414mA
13S,414mA
0.840
90
100
115
135
180
220
AC input (Vac)
240
265
Figure 13. Power Factor (PF) vs. Wide AC Voltage in T8(18W, 12S / 425mA) Tube
Rev. 1.30
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June 26, 2015
HT7L4811
25
THD(%)
20
15
10
5
E27 8W (13S, 162mA)
T8 18W (12S, 425mA)
0
90
100
115
135
180
220
240
264
AC Input (VAC)
Figure 14. E27/T8 THD vs. Wide AC Voltage
Note: * 425mA is typical current limit. Actual LED current will be variable due to sense resistor tolerance.
Typical Application Circuit
LED+
90Vac ~ 265Vac
LED -
DRV
GND
VCC
HT7L4811
ZCD
CS
COMP
Application Information
Start-up Current
The HT7L4811 is a universal AC/DC LED driver
designed for LED lighting applications. The device
can achieve high Power Factor values without
resorting to additional circuits and can also generate
high accuracy LED drive currents with very few
external components. Separate grounds are provided;
one is a floating ground for the HT7L4811 while the
other one is the earth. Users should be aware that the
two grounds cannot be directly connected together to
avoid IC damage and system malfunction.
A very low start-up current, ISTART, allows the users
to select a larger value of start-up resistor which
reduces power dissipation.
Rev. 1.30
VCC Under Voltage Lockout – UVLO
The device includes a UVLO feature which has 8V
hysteresis. The PWM controller turns on when VCC
is higher than 18V and turns off when VCC is lower
than 10V. The hysteresis characteristics guarantee
that the device can be powered by an input capacitor
during start-up. When the output voltage increases
to a certain value after start-up, VCC will be charged
by an output through an auxiliary winding or a Zener
Diode. VZ=VLED - VCC.
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June 26, 2015
HT7L4811
Boundary Conduction Mode – BCM
OVP on VCC – Over Voltage Protection
The power MOSFET is turned on by inductor current
zero-crossing detection. The current zero-crossing
can be detected by a ZCD voltage. When the inductor
current is at the zero crossing point, the voltage
on the ZCD pin will drop rapidly. The HT7L4811
then detects the falling edge and turns on the Power
MOSFET. The boundary conduction mode provides
low turn-on switching losses and high conversion
efficiency.
In order to prevent PWM controller damage, the
device includes an OVP function on VCC. Should
the VCC voltage be higher than the OVP threshold
voltage of 29V, the PWM controller will stop
operating immediately. When the VCC voltage
decreases below the UVLO off level, the controller
will reset.
Zero Current Detection – ZCD
The LED voltage is reflected on the ZCD pin
through a resistor RZCD. When the current on the
resistor RZCD is higher than 300μA, then ZCD OVP
protection will take place. Here the PWM controller
will stop operating immediately. When the VCC
voltage decreases below the UVLO off level, the
controller will reset.
LED Open Protection – ZCD OVP
The ZCD voltage is designed to operate between 0V
and 3V for normal operation. If the voltage on the
ZCD pin goes higher than 1.5V, the ZCD comparator
waits until the voltage goes below 1V. When the
inductor current is at the zero crossing point, the
voltage on the ZCD pin will drop rapidly. The device
will then detect the 1V falling edge and turn on the
Power MOSFET. The 0.5V hysteresis avoids any false
triggering actions due to noise.
VOVP-ZCD can be set using the following equation:
VOVP−ZCD = VZCDH + IOVP × RZCD
The VZCDH is the upper clamp voltage 3V on the ZCD
pin. The IOVP represents the OVP current level on the
ZCD pin which is 300μA. The RZCD stands for the
resistor connected between the ZCD pin and the LED
positive terminal.
Constant Current Control
The HT7L4811 will sense the overall inductor
current and form a closed-loop with an internal error
amplifier to obtain high constant current accuracy.
The CS voltage and the 0.2V reference voltage are the
inputs of a Gm amplifier whose output is integrated
via an external COMP capacitor. The ON time of the
MOSFET is controlled by the COMP voltage to adjust
the output current.
OCP – Over Current Protection
The HT7L4811 includes an over current protection
function on the CS pin. An internal circuit detects the
current level and when the current is larger than the
over current protection threshold level, VOCP/RCS, the
gate output will remain at a low level.
LEB on CS – Leading-Edge Blanking
LED Short Protection – SCP
Each time the external power MOSFET is switched
on, a turn-on spike will inevitably occur at the sense
resistor. To avoid faulty triggering, a 400ns leadingedge blank time is generated. As this function is
provided conventional RC filtering is therefore
unnecessary. During this blanking period, the currentlimit comparator is disabled and can therefore not
switch off the gate driver.
The output voltage drops when a number of LEDs
in a string are shorted resulting in a voltage drop at
VCC. Once the VCC drops below 10V, the device
will stop operating. Under such situations, the start-up
operation will recharge the VCC pin through the startup resistor and the device will enter the UVLO hiccup
mode.
Gate Driver Clamp
Thermal Protection
The DRV pin is connected to the gate of external
MOSFET to control its ON/OFF function. To protect
the external power MOSFET from being overstressed, the gate driver output is clamped to 17V.
Rev. 1.30
A thermal protection feature is included to protect
the device from excessive heat damage. When the
junction temperature exceeds a threshold of 150°C,
the thermal protection function will turn off the DRV
terminal immediately. When the VCC decreases
below the UVLO off level, the controller will reset.
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June 26, 2015
HT7L4811
Package Information
Note that the package information provided here is for consultation purposes only. As this information may be
updated at regular intervals users are reminded to consult the Holtek website for the latest version of the Package/
Carton Information.
Additional supplementary information with regard to packaging is listed below. Click on the relevant section to be
transferred to the relevant website page.
• Package Information (include Outline Dimensions, Product Tape and Reel Specifications)
• The Operation Instruction of Packing Materials
• Carton information
Rev. 1.30
10
June 26, 2015
HT7L4811
6-pin SOT23-6 Outline Dimensions
Symbol
Nom.
Max.
A
—
—
0.057
A1
—
—
0.006
A2
0.035
0.045
0.051
b
0.012
—
0.020
0.009
C
0.003
—
D
—
0.114 BSC
—
E
—
0.063 BSC
—
—
e
—
0.037 BSC
e1
—
0.075 BSC
—
H
—
0.110 BSC
—
L1
—
0.024 BSC
—
θ
0°
—
8°
Symbol
Rev. 1.30
Dimensions in inch
Min.
Dimensions in mm
Min.
Nom.
Max.
A
—
—
1.45
A1
—
—
0.15
A2
0.90
1.15
1.30
b
0.30
—
0.50
C
0.08
—
0.22
D
—
2.90 BSC
—
E
—
1.60 BSC
—
e
—
0.95 BSC
—
e1
—
1.90 BSC
—
H
—
2.80 BSC
—
L1
—
0.60 BSC
—
θ
0°
—
8°
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June 26, 2015
HT7L4811
Copyright© 2015 by HOLTEK SEMICONDUCTOR INC.
The information appearing in this Data Sheet is believed to be accurate at the time
of publication. However, Holtek assumes no responsibility arising from the use of
the specifications described. The applications mentioned herein are used solely
for the purpose of illustration and Holtek makes no warranty or representation that
such applications will be suitable without further modification, nor recommends
the use of its products for application that may present a risk to human life due to
malfunction or otherwise. Holtek's products are not authorized for use as critical
components in life support devices or systems. Holtek reserves the right to alter
its products without prior notification. For the most up-to-date information, please
visit our web site at http://www.holtek.com.tw.
Rev. 1.30
12
June 26, 2015