The HT7L2102 is an advanced, highly integrated LED
Lighting driver using an AC-DC isolation topology.
The device provides many protection functions and
uses ultra low power circuit design, and is optimized
to restrict EMI. By integrating a Non-Audible Noise
Green Mode Control Structure, users can implement
a single circuit for different LED load levels for
various series/parallel configurations but still maintain
high efficiency for different load conditions. This
device also integrates various protection functions for
LED Lighting requirements such as Cycle-by-Cycle
Current Limiting, Short-Circuit Protection (SCP),
Over-Voltage Protection (OVP), Over-Temperature
Protection (OTP) for external thermistor sensing, and
a Soft-Start function to reduce inrush currents during
LED power system initialization for the prevention of
device burn-out.
The HT7L2102 provides a 1~99% PWM Dimming
Range with duty-cycle scale precision lower than 1%.
Applications
• Isolation AC-DC LED Lighting
• AC-DC Switching Power Supply/Adapter
Application Circuits
L
Vac=85V~265V
BD1
C2
R7
R3
C14
R4
8
T1
1
7
D1
Vout
C4
N
D4
U1
C15
Vref
VCC
C12
5
D3
3
4
GD
RT
R11
ISENSE
TS
Rts
COMP/FB
GND
C19
Q1
R19
R20
U2
R28
Q3
Rev. 1.00
1
November 4, 2011
HT7L2102
Block Diagram
VREF
8
Pin Assignment
F B /P D M
VCC
Soft-Start
Driver
Stage
S Q
R
5
6
VCC
7
UVLO
OVP
32V
14V / 8V
T S
IS E N S E
R T
4
GD
1
8
2
7
3
6
5
H T 7 L 2 1 0 2
8 S O P -A
V R E F
V C C
G D
G N D
Internal Bias
& Vref
RT
4
Green Mode
OSC
GND
107uA
TS
2
Temperature
Sense
Frequency
Jitter
Slope
Compensation
FB/PDM
ISENSE
1
3
LEB
350ns
Constant
Current
Controller
OTP
SCP
OCP
OCP Level = 1V
FB Compare Level = 2.5V
Pin Description
Pin No.
1
2
3
4
5
6
7
8
Pin Name
FB/PDM
TS
ISENSE
RT
GND
GD
VCC
VREF
Description
Voltage Feedback Pin. Connected to a Photo-Coupler for closed-loop control. This pin also
can be used as a PWM Dimming Pin.
Temperature Sense Pin. Connected to an external thermistor as a sense system hot point.
This pin also can be used for an external System-Latch.
A voltage proportional to the inductor current is connected to this input. The Constant
Current Controller uses this voltage information to keep the system output current within a
narrow range.
The oscillator frequency is programmed by connecting a resistor RT between this pin and
ground. A maximum frequency of 500KHz is possible.
Combined control circuitry and power ground.
Power MOSFET gate driver output.
Positive Supply.
A Temperature-Independent Voltage Reference output.
Absolute Maximum Ratings
Supply Voltage VCC ................................................................................................................................ -0.3V~30.0V
Junction Temperature .......................................................................................................................................... 150°C
Operating Ambient Temperature .............................................................................................................. -40°C~85°C
.
Storage Temperature Range .................................................................................................................... -65°C~150°C
Human Body Model .....................................................................................................................................3kV
.
Machine Model ...........................................................................................................................................200V
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.
Rev. 1.00
2
November 4, 2011
HT7L2102
Electrical Characteristics
Symbol
I
ST
I
CC
V
TL
V
TH
V
CC
V
D-OVP
V
REF
∆V
REF
∆V
REF
V
IS(OFF)
t
LEB
Parameter
Startup Current
Operating Current
UVLO (Off)
UVLO (On)
OVP Trip Level
OVP Strobe Time
Output Voltage
Line Regulation
Load Regulation
Maximum Input Voltage, Vcs(off)
Leading Edge Blanking Time
Delay to Output
Oscillator (RT pin)
f
OSC
∆f
OSC
∆T
A
∆f
OSC
∆V
REF
D
MAX
Oscillator Frequency
Temperature Stability
Voltage Stability
Maximum Duty
Frequency Jitter
Gate Drive Output (GD Pin)
V
OL
V
OH
t
r
t
f
I
SINK
V
FB/PDM
V
FB/PDM
Soft-Start
t
START
V
OTP-On
V
OTP-Reset
I
TS
Soft-Start Time
OTP Enable Trigger Level
OTP Disable Trigger Level
Pull up Current Source
RT=10kW
—
0.95
—
96
10
1.00
1.2
107
—
1.05
—
118
ms
V
V
mA
External OTP(Over Temperature Protection, TS Pin)
Output Low Level
Output High Level
Rising Time
Falling Time
Short Circuit Current
Open Loop Voltage
SCP Trip Level
SCP Delay Time (See Note)
V
CC
=15V, Isink=20mA
V
CC
=15V, Isource=20mA
Tj=25°C, Load Capacitance=1nF
Tj=25°C, Load Capacitance=1nF
V
FB/PDM
=0V
FB/PDM pin open
V
FB/PDM
(SCP)
f
S
=52kHz
—
9
—
—
—
—
—
—
—
—
50
50
1.5
5.5
4.7
75
1
—
150
150
2.2
—
—
—
V
V
ns
ns
mA
V
V
ms
Tj=25°C, RT=10kW
to GND
-40°C ~105°C
V
CC
=10V~25V
—
—
49
—
—
—
—
52
5
0.2
75
±4
55
—
1.0
—
—
kHz
%
%/V
%
%
Supply Voltage (VCC Pin)
V
CC
=12.9V
V
FB/PDM
=0V
V
FB/PDM
=3V
—
—
V
CC
(Over Voltage Protection)
—
Tj=25°C, I
O
=1mA
12V ≤ V
CC
≤ 25V
1mA ≤ I
O
≤ 10mA
—
—
—
—
—
—
7
13
26.5
—
—
—
—
0.9
—
—
12
2.0
2.5
8
14
28.0
100
5.5
3
4
1.0
350
100
30
3.0
—
9
15
29.5
—
—
20
25
1.1
—
—
mA
mA
mA
V
V
V
ms
V
mV
mV
V
ns
ns
Unless otherwise stated, this specifications apply for 0°C ≤ Ta ≤ 70°C, V
CC
=15V, RT=10kW
Test Condition
Min.
Typ.
Max.
Unit
Reference Section (VREF Pin)
Current Sensing (ISE NSE Pin)
Voltage Feedback (FB/PDM Pin)
SCP (Short Circuit Protection)
Note: These Parameters, although guaranteed, are not 100% tested in production.
Rev. 1.00
3
November 4, 2011
HT7L2102
Typical Performance Characteristics
15.5
15
14.5
14
13.5
13
12.5
12
11.5
-40
-20
0
20
40
60
80
100
120
UVLO (off)(V)
10
9.5
9
8.5
8
7.5
7
6.5
6
-40
10
60
Temperature (degree C)
110
UVLO (on)(V)
Temperature (degree C)
Figure 1. UVLO (on) (V) vs. Temperature
Figure 2. UVLO (off) (V) vs. Temperature
57
56
55
54
53
52
51
50
49
48
47
-40
-20
0
20
40
60
80
100
120
57
56
55
54
53
52
51
50
49
48
47
11
Frequency (KHz)
Frequency (KHz)
13
15
17
Vcc (V)
19
21
23
25
Temperature (degree C)
Figure 3. Frequency vs. Temperature
Figure 4. Frequency vs. V
CC
4.9
4.85
4.8
4.75
4.7
4.65
4.6
4.55
4.5
4.45
4.4
-40
Green Mode Frequency (KHz)
31
29
27
25
23
21
19
17
15
11
13
15
17
19
Vcc (V)
21
23
25
Vcomp (V)
-20
0
20
40
60
80
100
120
Temperature (degree C)
Figure 5. V
FB/PDM
for SCP vs. Temperature
Figure 6. Green Mode Frequency vs. V
CC
Rev. 1.00
4
November 4, 2011
HT7L2102
Application Information
Operation Overview
The HT7L2012 is a highly functionally integrated
PWM controller for LED lighting and is optimized to
restrict EMI. The device offer a dimming precision of
less than 1% and has a dimming range of 1% to 99%.
Its integrated features include Green mode (Non-
Acoustic-Noise), internal slope compensation, high
efficiency under different load conditions within a
wide operating temperature range of -40°C to 85°C.
The devices also includes a range of protection
functions, SCP, OVP, UVLO, current limit, LEB,
soft start, OTP for external thermistor sensing. These
features not only enhance system performance,
but also ensure high stability of the whole circuit
application even under extreme environmental
conditions such as high temperature or high EMI
levels.
Advanced Precision Oscillator for
Green-Mode Switching and Non-Acoustic
Noise Requirement
A Trimmed Precision Green Mode Oscillator is
implemented in the device to enhance the conversion
efficiency under light load conditions. As Fig. 7
shows, the efficiency difference between light loads
and heavy loads is less than 1%, while the average
efficiency is only 89.5%, the peak efficiency is 90%.
Figure 8. Oscillator Behavior Compared with
HT7L2102 and Other Green Mode PWM Controller
Frequency Jitter for EMI Restriction
EMI restriction is accomplished using a Frequency
Jitter function, which spreads the energy over a wider
frequency range than the bandwidth measured by
the EMI test equipment. An internal Frequency Jitter
circuit changes the switching frequency between +4%
and -4% of the central frequency with a period of
4ms.
Figure 7 HT7L2102 Efficiency Performance
between Light-Load and Heavy-Load
The Green Mode Oscillator types supplied by other
PWM Controller providers are plagued by Acoustic-
Noise problems. This is because, under light load
conditions, the frequency will keep decreasing
through the Human Acoustic Range (from 20Hz
to 20kHz), and these audio frequencies may create
audible noise in the transformer. Holtek’s HT7L2102
patented Green Mode Oscillator designed using an
advanced Non-Acoustic Noise structure prevents
the generation of frequencies in the audio frequency
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