Data Sheet

HT7L4661
Active PFC Non-isolation Buck LED
Lighting Driver With Dimming Function
Feature
Applications
• Non-isolation buck topology
• General illumination
• Wide AC input range − from 85VAC to 265VAC
• E26/27, T5/T8 LED Lamp
• High Power Factor of >0.9 without additional
circuitry
• Other LED Lighting Applications
• Internal 650V high voltage JFET for quick startup
General Description
• Provides 5V LDO output
The HT7L4661 is a Buck converter controller using
quasi-resonant conversion technology. It can be used
for driving high-brightness LEDs with power factor
correction in off-line applications. The controller is
implemented by driving an external power MOSFET
and measuring and regulating a constant LED current.
• Accurate constant current (< ±3%)
• Includes linear dimming function
• Low operating current to maximise conversion
efficiency
• Under-voltage lockout with hysteresis
Additional features in the device include a rapid high
voltage startup function and a 5V LDO output with a
1mA drive capability for external loads. There is also a
linear dimming function to adjust the LED illumination
level.
• Full protection functions for enhanced safety
–– Maximum gate drive output 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
–– CS, ZCD pins open protection
–– On-chip Vver temperature protection − OTP
The device also includes multiple protection features
to protect it from fault conditions. These include
under-voltage lockout, over-current protection, Vcc
pin over-voltage protection and a ZCD pin overvoltage protection for the output voltage. Additionally,
to ensure device reliability, there is also a fully
integrated thermal protection function.
• Small 10-pin MSOP package
Application Circuits
ACIN
VOUT+
VOUT-
1
2
3
HV N.C DRV
VSS
9
CS
7
COMP
DIM
8
REG5V
6
OUT
VDD
5
GND
HT7L4661
4
VDD
10
ZCD
Controller
Rev. 1.00
1
January 26, 2015
HT7L4661
Block Diagram
VCC
REG5V
VCC
Clamping
LDO
HV
Start-up
Reference
& Bias
OVP1
HV
UVLO
Driver
DRV
Minimum
Off Time
ZCD
Comparator
ZCD
OVP2
Logic
Control
OTP
Starter
OCP
CS
Linear
Dimmimg
PWM
Generator
EA
Vref
DIM
COMP
LEB
GND
Pin Assignment
HV
NC
DRV
VCC
GND
1
10
2
9
3
8
4
7
5
6
ZCD
CS
DIM
COMP
REG5V
HT7L4661
10 MSOP-A
Rev. 1.00
2
January 26, 2015
HT7L4661
Pin Description
Pin No.
Pin Name
Description
1
HV
High-Voltage startup pin. The HV pin is connected to the AC line voltage to provide the
charging current to the VCC capacitor.
2
NC
No Connection
3
DRV
Output to drive the external power MOSFET
4
VCC
Internal circuitry power supply pin. Must be bypassed with a capacitor to GND with value of
at least 10μF.
5
GND
Ground
6
REG5V
5V LDO output. Must be bypassed with capacitor to GND with value of at least 1uF.
7
COMP
Error amplifier output. A capacitor is placed between COMP and GND to provide a stable
frequency response.
8
DIM
Linear dimming input. Sets the current sense threshold as long as the voltage at this pin is
less than 3V.
9
CS
Current sense pin. A resistor is connected here for MOSFET current sensing.
10
ZCD
Zero-current detect pin. Input from auxiliary winding for zero-current detection and output
over-voltage sensing.
Absolute Maximum Ratings
VCC Supply Voltage����������������������������������������������������������������������������������������������������������������������������������� -0.3V~33V
HV Voltage������������������������������������������������������������������������������������������������������������������������������������������������ -0.3V~650V
DIM, CS,COMP, LDO Pins�������������������������������������������������������������������������������������������������������������������������� -0.3V~6V
ZCD pin Maximum current������������������������������������������������������������������������������������������������ 3mA (source), 3mA (sink)
Maximum Junction Temperature������������������������������������������������������������������������������������������������������������������������ 150°C
Storage Temperature Range�������������������������������������������������������������������������������������������������������������������� -55°C~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
VCC Supply Voltage������������������������������������������������������������������������������������������������������������������������������������� 17V~25V
Operating Junction Temperature������������������������������������������������������������������������������������������������������������� -40°C~125°C
Rev. 1.00
3
January 26, 2015
HT7L4661
Electrical Characteristics
Symbol
VCC=18V, Ta=25°C
Parameter
Test Condition
Min.
Typ.
Max.
Unit
Power Supply (VCC Pin)
VCCON
Turn-on Threshold
—
—
16
—
V
VCCOFF
Turn-off Threshold
—
—
8.4
—
V
Hys
Hysteresis
—
6.8
—
—
V
VOVP
OVP level on VCC pin
—
26
29
32
V
ISTART
Start-up Current
Before turn-on, VCC=11V
—
45
60
μA
IQ
Quiescent Current
No switching
—
—
700
μA
ICC
Operating Current
70kHz, CO=1nF
—
—
3
mA
High Voltage Start-up
VCCST(ON)
High V section Turn-on Threshold
—
—
17
—
V
VCCST(OFF)
High V section Turn-off Threshold
—
—
10
—
V
Hys
Hysteresis
—
—
7
—
V
V
Linear Regulator
VCC
LDO Input Voltage
—
8
—
30
Reg5V
Regulated Output Voltage
—
4.5
5
5.5
V
IOUT(STD)
Output Current at Standby Mode
VDIM < 0.4V
1
—
—
mA
IOUT(OP)
Output Current at Operating Mode
VDIM > 0.4V
5
—
—
mA
Voltage Feedback Input Threshold
Tj=25°C
194
200
206
mV
Error Amplifier
VFB
Current Sense Comparator
tLEB
VOCP
VCL
Leading Edge Blanking Time
—
—
400
—
ns
Over Current Protection Threshold
—
—
0.9
—
V
Over Current Release Threshold
—
—
0.2
—
V
Current Limit Threshold
—
—
1.3
—
V
—
3
—
V
Zero Current Detector
VZCDH
Upper Clamp Voltage
IZCD=300μA
VZCDL
Lower Clamp Voltage
IZCD=-2.5mA
—
-0.2
—
V
VZCDA
Positive-Going Edge
—
—
1.5
—
V
VZCDT
Negative-Going Edge
—
—
1
—
V
IOVP
ZCD pin OVP current level
—
285
300
315
μA
tB_OVP
OVP Detection Blanking Time
—
tSTART
Start Timer Period
—
—
40
—
μs
tOFF
Minimum Off Time
—
—
4
—
μs
Over Temperature Lockout
—
—
150
—
°C
Over Temperature Resume
—
—
110
—
°C
1
μs
Starter
Over Temperature Protection
OTP
Gater Driver
tR
Rise Time
Co=1nF, 10%~90%
—
100
—
ns
tF
Fall Time
Co=1nF, 10%~90%
—
70
—
ns
VCLAMP
Gate Clamp Voltage
VCC=25V
—
—
19.5
V
Dimming
VDIM
Linear Dimming Range
—
0.4
—
3
V
Vsat
Saturation Threshold Voltage
—
—
3
—
V
Vled(off)
LED Current off Threshold Voltage
—
—
0.4
—
V
Note: These Parameters, although guaranteed, are not 100% tested in production.
"*" Suggest to limit switching frequency under 75kHz for Green Mode operation.
Rev. 1.00
4
January 26, 2015
HT7L4661
Typical Performance Characteristics
60
Operating Current (μA)
Start-up Current (μA)
55
50
45
40
35
30
25
-40
-20
0
20
40
60
Temperature (℃)
80
100
120
-40
0
20
40
60
Temperature (℃)
80
100
120
Figure 2. Operation current vs. temperature
17.0
8.5
16.9
8.4
16.8
8.3
16.7
8.2
16.6
16.5
16.4
16.3
8.1
8.0
7.9
7.8
16.2
7.7
16.1
7.6
16.0
-40
-20
0
20
40
60
Temperature (℃)
80
100
7.5
120
-40
Figure 3. UVLO_on vs. temperature
18.0
11.0
17.9
10.8
17.8
10.6
17.7
10.4
17.6
17.5
17.4
17.3
20
40
60
Temperature (℃)
80
100
9.0
120
Figure 5. UVLO(st)_on vs. temperature
Rev. 1.00
100
120
9.6
9.2
0
80
9.8
9.4
-20
20
40
60
Temperature (℃)
10.0
17.1
-40
0
10.2
17.2
17.0
-20
Figure 4. UVLO_off vs. temperature
UVLO(st)_off (V)
UVLO(st)_on (V)
-20
Figure 1. Start-Up current vs. temperature
UVLO_off (V)
UVLO_on (V)
20
800
775
750
725
700
675
650
625
600
575
550
525
500
-40
-20
0
20
40
60
Temperature (℃)
80
100
120
Figure 6. UVLO(st)_off vs. temperature
5
January 26, 2015
VFB (mV)
5.20
Operating Mode LDO Voltage (V)
Standby Mode LDO Voltage (V)
HT7L4661
5.15
5.10
5.05
5.00
4.95
4.90
4.85
4.80
206
205
204
203
202
201
200
199
198
197
196
195
194
-40
-20
0
20
40
60
Temperature (℃)
80
100
120
5.20
5.15
5.10
5.05
5.00
4.95
4.90
4.85
4.80
-40
-20
0
20
40
60
Temperature (℃)
80
100
120
Figure 7. LDO Voltage
Figure 8. LDO Voltage (Operating Mode) vs.
(Standby Mode) vs. Temperature
Temperature
-40
-20
0
20
40
60
Temperature (℃)
80
100
120
Figure 9. VFB vs. Temperature
Rev. 1.00
6
January 26, 2015
HT7L4661
Functional Description
The HT7L4661 is a universal AC/DC LED driver designed for LED lighting applications. The device can
achieve high Power Factor values without resorting
to additional external circuity 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 HT7L4661 while the
other one is for ground. It is important to note that the
two grounds cannot be directly connected together to
avoid IC damage and system malfunction.
Zero Current Detection − ZCD
The ZCD voltage is designed to operate between 0V
and 3V for normal operation. If the voltage on the
ZCD pin ����������������������������������������
increases�������������������������������
higher than 1.5V, the ZCD comparator waits until the voltage falls 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 of hysteresis avoids any
false triggering actions due to noise.
High Voltage Start-up
Constant Current Control
Due to its internal high-voltage startup circuit, when
an AC voltage is applied to the power system, the
device provides a high current to charge the external
Vcc capacitor to speed up the system startup time.
To save power consumption, after the Vcc voltage
has exceeded the turn-on voltage and enters normal
operation, the high-voltage startup circuit is shutdown.
The device 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 form the inputs to a Gm
amplifier whose output is integrated using an external
C������������������������������������������������
OMP���������������������������������������������
capacitor. The �����������������������������
ON���������������������������
time of ������������������
the ��������������
MOSFET is controlled by the COMP voltage to adjust the LED current.
VCC Under Voltage Lockout − UVLO
Leading-Edge Blanking − LEB on CS
The device includes a UVLO feature which includes
a 6.8V hysteresis value. The PWM controller turns
on when VCC is higher than 16V and turns off when
VCC is lower than 8.4V. 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.
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 c��������������������������������������������
onventional RC filtering �������������������
is therefore ������
unnecessary. During this blanking period, the current-limit
comparator is disabled and can therefore not switch
off the gate driver.
Low Dropout Regulator − LDO
Gate Driver Clamp
A low dropout regulator (LDO) is included in the
device and provides a stable 5V output voltage for
other devices. When the dim voltage is lower than
0.4V, the LDO obtains its power from the high voltage
start-up circuit and the drive current of LDO is 1mA.
During normal operation, VCC will be charged by an
output��������������������������������������������
�������������������������������������������
through �����������������������������������
an ��������������������������������
auxiliary winding or �����������
a ���������
Zener Diode. Thus, the driving current of LDO can increase to
5mA.
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.
Over Voltage Protection − OVP on VCC
In order to prevent PWM controller damage, the
device includes an OVP function for VCC. Should the
VCC voltage ��������������������������������������
be������������������������������������
higher than the OVP threshold voltage of 29V, the PWM controller will stop operation
immediately. When the VCC voltage decreases below
the UVLO off level, the controller will reset.
Boundary Conduction Mode − BCM
The power MOSFET is turned on by inductor current
zero-crossing detector. 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 device 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.
Rev. 1.00
7
January 26, 2015
HT7L4661
LED Open Protection − ZCD OVP
Thermal Protection
The LED voltage is reflected on the ZCD pin through
a resistor RZCD. When the current through the
RZCD resistor is higher than 300μA, then ZCD OVP
protection will take place���������������������
and ����������������
the PWM controller will stop operation immediately. When the VCC
voltage ��������������������������������������������
decreases below ����������������������������
the ������������������������
UVLO off level, the controller will reset.
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.
Dimming Function
VOVP-ZCD can be set using the following equation:
On the DIM pin, when the voltage on this pin is lower
than 0.4V, the device output driving operation will
be shut down and the LED current will reduce to
zero for this condition. When the voltage is between
0.4V and 3V, the device will be operating in its linear
dimming range and the LED current will be controlled
according to the pin voltage. While the pin voltage is
higher than 3V, the device will operate in its normal
operating condition.
VOVP − ZCD = VZCDH + IOVP × R ZCD
The VZCDH is the upper clamp voltage of 3V on the
ZCD pin. The IOVP represents the OVP current level
on the ZCD pin which is 300μA. RZCD stands for the
resistor connected between the ZCD pin and the LED
positive terminal.
Over Current Protection − OCP
The ������������������������������������������������
device������������������������������������������
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.
Standby Mode Range
Iout(%)
100
LED Short Protection − SCP
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 8.4V, 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.
Rev. 1.00
Saturation
Range
13.3
0.4
8
Linear Dimming
Range
Vdim(V)
Iout
3
January 26, 2015
HT7L4661
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
information.
Additional supplementary information with regard to packaging is listed below. Click on the relevant section to be
transferred to the relevant website page.
• Further Package Information (include Outline Dimensions, Product Tape and Reel Specifications)
• Packing Meterials Information
• Carton information
Rev. 1.00
9
January 26, 2015
HT7L4661
10-pin MSOP Outline Dimensions
Symbol
Nom.
Max.
A
—
—
0.043
A1
0.000
—
0.006
A2
0.030
0.033
0.037
B
0.007
—
0.013
C
0.003
—
0.009
D
—
0.118 BSC
—
E
—
0.193 BSC
—
E1
—
0.118 BSC
—
e
—
0.020 BSC
—
L
0.016
0.024
0.031
L1
—
0.037 BSC
—
y
—
0.004
—
θ
0°
—
8°
Symbol
Rev. 1.00
Dimensions in inch
Min.
Dimensions in mm
Min.
Nom.
Max.
A
—
—
1.10
A1
0.00
—
0.15
A2
0.75
0.85Q
0.95
B
0.17
—
0.33
C
0.08
—
0.23
D
—
3.00 BSC
—
E
—
4.90 BSC
—
E1
—
3.00 BSC
—
e
—
0.50 BSC
—
L
0.40
0.60
0.80
L1
—
0.95 BSC
—
y
—
0.10
—
θ
0°
—
8°
10
January 26, 2015
HT7L4661
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.
Rev. 1.00
11
January 26, 2015