AL9901S16-13 [DIODES]
UNIVERSAL HIGH VOLTAGE LED DRIVER;
| 型号： | AL9901S16-13 |
| 厂家： | 
DIODES INCORPORATED |
| 描述： | UNIVERSAL HIGH VOLTAGE LED DRIVER 驱动 高压 |
| 文件： | 总20页 (文件大小：681K) |
| 中文： | 中文翻译 | 下载： | 下载PDF数据表文档文件 |
AL9901
UNIVERSAL HIGH VOLTAGE LED DRIVER
Description
Pin Assignments
The AL9901, high-voltage PWM LED driver provides an efficient
solution for offline, high-brightness LED lamps for rectified line
voltages ranging from 85VAC up to 305VAC. The AL9901 has an
internal MOSFET that allows switching frequencies up to 300kHz,
with the switching frequency determined by an external single
resistor. The AL9901 topology creates a constant current through the
LEDs providing constant light output. The output current is
programmed by one external resistor.
The LED brightness can be varied by both Linear and PWM dimming,
using the AL9901’s LD and PWM pins respectively. The PWM input
operates with a duty ratio of 0-100% and a frequency of up to several
kHz.
U-DFN6040-12
The AL9901 is available in the thermally enhanced U-DFN6040-12
and SO-16 packages. The SO-16 is compliant to high voltage spacing
rules for 230VAC mains applications.
Features
•
•
•
•
•
•
•
•
•
•
•
•
>90% Efficiency
Universal Rectified 85 to 305VAC Input Range
Internal MOSFET Up to 650V, 2A
High Switching Frequency Up to 300kHz
Internal Voltage Regulator Removes Start-Up Resistor
7.5V Regulated Output
SO-16
Tighter Current Sense Tolerance Better Than 5%
LED Brightness Control with Linear and PWM Dimming
Internal Over-Temperature Protection (OTP)
U-DFN6040-12 and SO-16 Packages
Applications
•
•
•
•
•
LED Offline Lamps
High Voltage DC-DC LED Driver
Totally Lead-Free & Fully RoHS Compliant (Notes 1 & 2)
Halogen and Antimony Free. “Green” Device (Note 3)
Signage and Decorative LED Lighting
Back Lighting of Flat Panel Displays
General Purpose Constant Current Source
Notes:
1. No purposely added lead. Fully EU Directive 2002/95/EC (RoHS) & 2011/65/EU (RoHS 2) compliant.
2. See http://www.diodes.com for more information about Diodes Incorporated’s definitions of Halogen- and Antimony-free, "Green" and Lead-free.
3. Halogen- and Antimony-free "Green” products are defined as those which contain <900ppm bromine, <900ppm chlorine (<1500ppm total Br + Cl) and
<1000ppm antimony compounds.
Typical Applications Circuit
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AL9901
Document number: DS37713 Rev. 1 - 2
AL9901
Pin Descriptions
Pin Name U-DFN5040-10
SO-16
Functions
Gate
NC
1
2
3
14
Gate of Internal MOSFET switch.
1, 2, 4, 10,16 No connection
PWM
5
Low Frequency PWM Dimming pin, also Enable input. Internal 200kΩ pull-down to GND
Internally regulated supply voltage, 7.5V nominal.
Can supply up to 1 mA for external circuitry. A sufficient storage capacitor is used to provide
storage when the rectified AC input is near the zero crossing.
4
5
VDD
LD
6
7
8
Linear Dimming input. Changes the current limit threshold at current sense comparator and
changes the average LED current.
Oscillator control.
A resistor connected between this pin and ground puts the AL9901 into fixed frequency mode and
sets the switching frequency. A resistor connected between this pin and Gate pin puts the AL9901
into fixed off-time mode and determines the off-time.
6
ROSC
9
Input voltage
7
8
9
VIN
CS
11
12
13
Senses LED string and internal MOSFET switch current
Device ground
GND
Gate driver output. Connect a resistor between this pin and ROSC pin to put the AL9901 into fixed
off time mode.
DRV
10
SO
SW
EP1
11
12
15
3
Source of the internal MOSFET Switch
Drain of the internal MOSFET switch.
EP1
NA
NA
Exposed Pad 1(bottom). Drain connection of internal power MOSFET.
Exposed Pad 2 (bottom). Substrate connection of control IC. Connect to GND directly underneath
the package and large PCB area to minimise junction to ambient thermal impedance.
EP2
EP2
Functional Block Diagram
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AL9901
Document number: DS37713 Rev. 1 - 2
AL9901
Absolute Maximum Ratings (Note 4) (@TA = +25°C, unless otherwise specified.)
Symbol
VIN(MAX)
VCS
Parameter
Maximum Input Voltage, VIN, to GND
Ratings
-0.5 to +520
-0.3 to +0.45
-0.3 to (VDD +0.3)
-0.3 to (VDD +0.3)
-0.5 to +650
-0.5 to (VDD +0.3)
-0.5 to (VDD +0.3)
8.1
Unit
V
Maximum CS Input Pin voltage Relative to GND
V
Maximum LD Input Pin Voltage Relative to GND
Maximum PWM_D input Pin Voltage Relative to GND
Maximum MOSFET Drain Pin Voltage Relative to GND
Maximum MOSFET Source Pin Voltage Relative to GND
Maximum MOSFET GATE pin Voltage Relative to GND
V
VLD
V
VPWM_D
VSW
V
V
VSO
V
VGate
VDD(MAX)
PDIS
V
Maximum VDD Pin Voltage Relative to GND
Continuous Power Dissipation (TA = +25°C)
U-DFN6040-12 (derate 10mW/°C above +25°C)
Junction Temperature Range
-
-
-
1,000
mW
°C
°C
V
+150
TJ
Storage Temperature Range
-65 to +150
2,000
TST
ESD HBM
Human Body Model ESD Protection (Note 5)
Notes:
4. Stresses above those listed under Absolute Maximum Ratings may cause permanent damage to the device. This is a stress rating only; functional
operation of the device at these or any other conditions above those listed in the operational sections of this specification is not implied. Exposure to
absolute maximum rating conditions for extended periods may affect device reliability.
All voltages are with respect to Ground. Currents are positive into, negative out of the specified terminal.
5. Semiconductor devices are ESD sensitive and may be damaged by exposure to ESD events. Suitable ESD precautions should be taken when handling
and transporting these devices
Maximum Ratings of Internal MOSFET (@TA = +25°C, unless otherwise specified.)
Characteristic
Symbol
VDSS
Value
650
30
Units
Drain-Source Voltage
Gate-Source Voltage
V
V
VGSS
TC = +25°C
Steady
State
1.6
1
A
Continuous Drain Current (Note 5) VGS = 10V
Pulsed Drain Current (Note 6)
ID
TC = +100°C
3
0.8
22
5
A
A
IDM
IAR
Avalanche Current (Note 7) VDD = 100V, VGS = 10V, L = 60mH
mJ
V/ns
Repetitive Avalanche Energy (Note 7) VDD = 100V, VGS = 10V, L = 60mH
Peak Diode Recovery
EAR
dv/dt
Recommended Operating Conditions (@TA = +25°C, unless otherwise specified.)
Symbol
VINDC
TA
Parameter
Min
Max
500
+105
+85
0.4
Unit
V
Input DC Supply Voltage Range
15
-40
-40
-
Ambient Temperature Range (U-DFN6040-12)
Ambient Temperature Range (SO-16)
Switch Pin Output Current
°C
-
TA
A
ISW
-
8.1
V
VDD
Maximum Recommended Voltage Applied to VDD Pin (Note 6)
Pin PWM_D Input Low Voltage
0
1
VEN(lo)
VEN(hi)
Note:
V
Pin PWM_D Input High Voltage
2.4
VDD
6. When using the AL9901 in isolated LED lamps, an auxiliary winding might be used.
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AL9901
Document number: DS37713 Rev. 1 - 2
AL9901
Electrical Characteristics (@TA = +25°C, unless otherwise specified.)
Specifications apply to AL9901 unless otherwise specified
Symbol
Parameter
Conditions
Pin PWM_D to GND,
IN = 15V
Min
Typ
Max
Unit
mA
Shut-Down Mode Supply Current
-
0.5
1
IInsd
V
VIN =VIN(MIN)~ 500V, (Note 8) lDD(ext)= 0,
Gate pin open
Internally Regulated Voltage
7.2
7.5
8.1
V
VDD
-
-
1.0
7.2
-
mA
V
IDD(ext)
UVLO
∆UVLO
RPWM_D
VT
VDD Current Available for External Circuitry VIN = 15 to 100V (Note 7)
6.4
6.7
500
200
3
V
DD Under Voltage Lockout Threshold
VDD rising
-
mV
kΩ
V
VDD Under Voltage Lockout Hysteresis
PWM_D Pull-Down Resistance
MOSFET Threshold Voltage
VDD falling
150
250
-
VPWM_D= 5V
-
ISW = 0.5A
MOSFET Diodes Forward Voltage
Drain-Source On-Resistance
-
-
0.85
4.4
250
25
-
V
VFD
ID = 0.5A
-
-
Ω
RDS(ON)
VCS(hi)
Current Sense Threshold Voltage
237.5
20
80
-
262.5
30
mV
TA = -40°C to +125°C
ROSC = 1MΩ
Oscillator Frequency
kHz
fOSC
100
-
120
100
250
440
ROSC = 226kΩ
fPWMhf = 25kHz, at GATE, CS to GND.
TA = <125°C, VIN = 15V
VCS = 0.45V, VLD = VDD
Maximum Oscillator PWM Duty Cycle
Linear Dimming Pin Voltage Range
Current Sense Blanking Interval
%
mV
ns
DMAXhf
VLD
0
-
160
250
tBLANK
VIN = 15V, VLD = 0.15,
Delay From CS Trip to GATE lo
-
-
300
ns
°C
tDELAY
VCS = 0 to 0.22V after TBLANK
-
Thermal Shut-Down
-
-
-
-
-
-
+150
+50
65
-
-
-
-
-
-
TSD
TSDH
θJA
Thermal Shut-Down Hysteresis
-
Thermal Resistance Junction-to-Ambient
Thermal Resistance Junction-to-Case
Thermal Resistance Junction-to-Ambient
Thermal Resistance Junction-to-Case
°C/W
°C/W
°C/W
°C/W
U-DFN6040-12 (Note 8)
SOIC-16
5
θJC
100
15
θJA
θJC
Notes:
7. Also limited by package power dissipation capability, whichever is lower.
8. Device mounted on FR-4 PCB (25mm x 25mm 1oz copper, minimum recommended pad layout on top. For better thermal performance, larger
copper pad for heat-sink is needed.
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AL9901
Document number: DS37713 Rev. 1 - 2
AL9901
Internal MOSFET Characteristic
OFF CHARACTERISTICS (Note 9)
Symbol
Min
Typ
Max
Unit
Test Condition
Drain-Source Breakdown Voltage
Zero Gate Voltage Drain Current
Gate-Source Leakage
650
—
—
—
—
—
1
V
BVDSS
IDSS
VGS = 0V, ID = 250µA
µA
nA
VDS = 650V, VGS = 0V
—
100
IGSS
VGS = 30V, VDS = 0V
ON CHARACTERISTICS (Note 9)
Gate Threshold Voltage
Static Drain-Source On-Resistance
Diode Forward Voltage
3
—
4
5
5
1
V
Ω
V
VGS(th)
RDS (ON)
VSD
VDS = VGS, ID = 250µA
VGS = 10V, ID = 1A
VGS = 0V, IS = 1A
—
—
0.7
DYNAMIC CHARACTERISTICS (Note 10)
Input Capacitance
—
—
—
—
—
—
—
—
—
—
—
—
—
—
—
—
—
—
—
—
—
—
—
—
—
—
pF
pF
pF
Ω
Ciss
Coss
Crss
Rg
479
29
V
DS = 25V, VGS = 0V,
Output Capacitance
f = 1MHz
Reverse Transfer Capacitance
Gate Resistance
1.9
2
VDS = 0V, VGS = 0V, f = 1MHz
14
Total Gate Charge
nC
nC
nC
ns
ns
ns
ns
ns
nC
Qg
V
DS = 520V, VGS = 10V,
2.5
7.3
17
Gate-Source Charge
Qgs
Qgd
tD(on)
tr
I
D = 2A
Gate-Drain Charge
Turn-On Delay Time
33
Turn-On Rise Time
VDS = 325V, VGS = 10V,
RG = 25Ω, ID = 2.5A
31
Turn-Off Delay Time
tD(off)
tf
25
Turn-Off Fall Time
174
884
Body Diode Reverse Recovery Time
Body Diode Reverse Recovery Charge
trr
VDS = 100V, IF = 2A,
di/dt = 100A/µs
Qrr
Notes: 9. Short duration pulse test used to minimize self-heating effect.
10. Guaranteed by design. Not subject to production testing.
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AL9901
Document number: DS37713 Rev. 1 - 2
AL9901
Typical Characteristics
3.0
460
440
2.5
2.0
1.5
V
= 400V
IN
420
400
380
360
340
320
V
= 15V
IN
1.0
0.5
0.0
-0.5
-1.0
-1.5
300
280
-40
-15
10
35
AMBIENT TEMPERATURE (°C)
60
85
-40
-15
10
35
AMBIENT TEMPERATURE (°C)
60
85
Change in Current Sense Threshold vs. Ambient Temperature
1.5
Input Current vs. Ambient Temperature
450
400
I
= 180mA
LED(NOM)
1.0
0.5
350
R
= 226kΩ
OSC
0.0
-0.5
-1.0
300
250
R
= 1MΩ
OSC
200
150
-1.5
-2.0
85 105 125 145 165 185 205 225 245 265
INPUT VOLTAGE (VRMS
180mA LED Driver Short Circuit Output Current vs. Input Voltage
-40
-15
10
35
60
85
)
AMBIENT TEMPERATURE (°C)
Change in Oscillation Frequency vs. Ambient Temperature
100
I
= 281mA
= 264V
LED
90
80
70
60
V
T
IN
= 23.5C
A
50
40
30
20
10
0
0
50
100
150
200
250
300
VLD DIMMING CONTROL (mV)
IOUT MAX vs. VLD Dimming Control
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AL9901
Document number: DS37713 Rev. 1 - 2
AL9901
Typical Characteristics (continued) measured using AL9901EV4
200
95
15 LEDs
14 LEDs
18 LEDs
190
180
170
90
17 LEDs
16 LEDs
14 LEDs
16 LEDs
17 LEDs
160
150
85
80
15 LEDs
18 LEDs
140
85 105 125 145 165 185 205 225 245 265
INPUT VOLTAGE (VRMS
180mA LED Driver Efficiency vs. Input Voltage
85 105 125 145 165 185 205 225 245 265
INPUT VOLTAGE (VRMS
)
)
180mA LED Driver Output Current vs. Input Voltage
0.95
0.9
12
10
17 LEDs
18 LEDs
18 LEDs
16 LEDs
0.85
0.8
16 LEDs
8
15 LEDs
17 LEDs
14 LEDs
15 LEDs
6
4
0.75
0.7
14 LEDs
85 105 125 145 165 185 205 225 245 265
INPUT VOLTAGE (VRMS
180mA LED Driver Power Factor vs. Input Voltage
85 105 125 145 165 185 205 225 245 265
INPUT VOLTAGE (VRMS
180mA LED Driver Input Power Dissipation vs. Input Voltage
)
)
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AL9901
Document number: DS37713 Rev. 1 - 2
AL9901
Typical Characteristics (cont.) measured using internal MOSFET
2.0
1.8
1.6
1.4
1.2
1.0
0.8
0.6
0.4
0.2
0.0
10
V
= 20V
GS
V
= 20V
DS
V
= 10V
GS
V
= 6.0V
GS
V
= 8.0V
GS
1
V
= 5.5V
0.1
GS
T
= 150°C
A
T
= 25°C
A
T
= 125°C
= 85°C
A
0.01
0.001
T
A
T
= -55°C
A
V
= 5.0V
GS
0
1
2
3
4
5
6
VGS, GATE-SOURCE VOLTAGE (V)
7
8
0
1
2
3
4
5
6
7
VDS, DRAIN-SOURCE VOLTAGE (V)
8
9
10
Typical Transfer Characteristics
Typical Output Characteristics
5
20
18
16
14
12
10
8
4.8
4.6
4.4
4.2
4
I
= 1.0A
D
V
= 10V
GS
3.8
3.6
3.4
3.2
3
6
4
2
0
4
6
8
10
12
14
16
18
20
0
0.2 0.4 0.6 0.8
1
1.2 1.4 1.6 1.8
2
ID, DRAIN-SOURCE CURRENT (A)
VGS, GATE-SOURCE VOLTAGE (V)
Typical On-Resistance vs. Drain Current and
Gate Voltage
Typical Transfer Characteristics
15
3
2.5
2
V
= 10V
GS
V
= 20V
GS
I
= 2A
12
9
T = 150°C
A
D
T
= 125°C
A
V
= 10V
GS
I
T
T
= 85°C
A
= 1A
D
1.5
1
6
= 25°C
A
3
T
= -55°C
A
0.5
0
0
0
0.2 0.4 0.6 0.8
1
ID, DRAIN CURRENT (A)
1.2 1.4 1.6 1.8
2
-50 -25
0
25
50
TJ, JUNCTION TEMPERATURE (
75 100 125 150
C)
°
Typical On-Resistance vs. Drain Current and
Temperature
On-Resistance Variation with Temperature
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AL9901
Document number: DS37713 Rev. 1 - 2
AL9901
15
12
5
4.5
4
I
= 1mA
D
I
= 250µA
V
= 20V
= 2A
D
GS
I
D
9
3.5
3
V
= 10V
= 1A
GS
I
D
6
3
0
2.5
2
-50 -25
0
25
50
75 100 125 150
C)
-50 -25
0
25
50
TJ, JUNCTION TEMPERATURE (°C)
75 100 125 150
TJ, JUNCTION TEMPERATURE (
°
On-Resistance Variation with Temperature
Gate Threshold Variation vs. Ambient Temperature
2
1.8
1.6
1.4
1000
C
iss
100
T
= 150°C
= 125°C
A
1.2
1
T
= 25°C
A
C
oss
T
A
0.8
0.6
0.4
0.2
0
T
= -55°C
A
10
T
= 85°C
A
C
rss
f = 1MHz
1
0
0.3
0.6
0.9
1.2
1.5
0
5
10
15
20
25
30
35
40
VSD, SOURCE-DRAIN VOLTAGE (V)
VDS, DRAIN-SOURCE VOLTAGE (V)
Diode Forward Voltage vs. Current
Typical Junction Capacitance
10
8
10
1
R
DS(on)
Limited
6
DC
V
I
= 520V
P
= 10s
DS
W
0.1
0.01
= 2A
D
P
= 1s
W
P
4
= 100ms
W
P
= 10ms
W
P
= 1ms
W
T
= 150°C
J(max)
2
T
= 25°C
P
= 100µs
A
W
V
= 10V
GS
Single Pulse
DUT on 1 * MRP Board
0.001
0
1
10 100
VDS, DRAIN-SOURCE VOLTAGE (V)
1000
0
2
4
6
8
10
12
14
16
Qg, TOTAL GATE CHARGE (nC)
Gate Charge
SOA, Safe Operation Area
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AL9901
Document number: DS37713 Rev. 1 - 2
AL9901
LED Current vs. Duty Cycle by PWM Dimming when VIN is
120Vac
LED Current vs. Duty Cycle by PWM Dimming when VIN is
230Vac
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AL9901
Document number: DS37713 Rev. 1 - 2
AL9901
Applications Information
The AL9901 is capable of operating in isolated or non-isolated topologies. It can also be made to operate in continuous as well as discontinuous
conduction mode.
Figure 1 Functional Block Diagram
The AL9901 contains a high voltage LDO (see figure 1) the output of the LDO provides a power rail to the internal circuitry including the gate
driver. A UVLO on the output of the LDO prevents incorrect operation at low input voltage to the VIN pin.
In a non-isolated Buck LED driver, when the gate pin goes high, the internal power MOSFET (Q1) is turned on causing current to flow through the
LEDs inductor (L1), and current sense resistor (RSENSE). When the voltage across RSENSE exceeds the current sense pin threshold, the internal
MOSFET Q1 is turned off. The energy stored in the inductor causes the current to continue to flow through the LEDs via diode D1.
The AL9901’s LDO provides all power to the rest of the IC including Gate drive, and this removes the need for large, high-power start-up resistors.
This means that during normal operation the AL9901 requires around 0.5mA from the high voltage power rail. The LDO can also be used to
supply up to 1mA to external circuits.
The AL9901 operates and regulates by limiting the peak current of the internal MOSFET; the peak current sense threshold is nominally set at
250mV. The AL9901 is capable of operating in a fixed frequency (PWM) mode and also variable frequency (fixed off-time) mode to regulate the
LED current.
The same basic operation is true for isolated topologies; however in these the energy stored in the transformer delivers energy to LEDs during the
off-cycle of the internal MOSFET.
The on-resistance of the AL9901’s internal power MOSFET means that it can drive up to 2A.
Design Parameters
Setting the LED Current
In the non-isolated buck converter topology, figure 1, the average LED current is not the peak current divided by two - however, there is a certain
error due to the difference between the peak and the average current in the inductor. The following equation accounts for this error:
250mV
RSENSE
=
ILED + (0.5* IRIPPLE
)
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AL9901
Document number: DS37713 Rev. 1 - 2
AL9901
Applications Information (continued)
Setting Operating Frequency
The AL9901 is capable of operating between 25 and 450 kHz switching frequency range. The switching frequency is programmed by connecting
an external resistor between ROSC pin and ground. The corresponding oscillator period is:
Rosc + 22
tOSC
=
µs
with ROSC in kΩ
25
The switching frequency is the reciprocal of the oscillator period. Typical values for ROSC vary from 75kΩ to 1MΩ
VLEDs
In buck mode the duty cycle, D, is
; so when driving small numbers of LEDs from high input voltages the duty cycle will be reduced and
VIN
care should be taken to ensure that tON > tBLANK. The simplest way to do this is to reduce/limit the switching frequency by increasing the ROSC
value. Reducing the switching frequency will also improve the efficiency.
When operating in buck mode the designer must keep in mind that the input voltage must be maintained higher than two times the forward voltage
drop across the LEDs. This limitation is related to the output current instability that may develop when the AL9901 operates at a duty cycle greater
than 0.5. This instability reveals itself as an oscillation of the output current at a sub-harmonic (SBO) of the switching frequency.
Inductor Selection
The non-isolated buck circuit, Figure 1, is usually selected and it has two operation modes: continuous and discontinuous conduction modes. A
buck power stage can be designed to operate in continuous mode for load current above a certain level, usually 15% to 30% of full load. Usually,
the input voltage range, the output voltage and load current are defined by the power stage specification. This leaves the inductor value as the
only design parameter to maintain continuous conduction mode. The minimum value of inductor to maintain continuous conduction mode can be
determined by the following example.
The required inductor value is determined from the desired peak-to-peak LED ripple current in the inductor; typically around 30% of the nominal
LED current.
(
VIN −VLEDs )× D
× fOSC
L =
Where, D is duty cycle
(0.3× ILED
)
The next step is determining the total voltage drop across the LED string. For example, when the string consists of 10 High-Brightness LEDs and
each diode has a forward voltage drop of 3.0V at its nominal current; the total LED voltage VLEDS is 30V.
Dimming
The LED brightness can be dimmed either linearly (using the LD pin) or via pulse width modulation (using the PWM-D pin); or a combination of
both - depending on the application. Pulling the PWM_Dpin to ground will turn off the AL9901. When disabled, the AL9901’s quiescent current is
typically 0.5mA (0.65 for AL9901A). Reducing the LD voltage will reduce the LED current but it will not entirely turn off the external power
transistor and hence the LED current – this is due to the finite blanking period. Only the PWM_Dpin will turn off the power transistor.
Linear dimming is accomplished by applying a 45 to 250mV analog signal to the LD pin. This overrides the default 250mV threshold level of the
CS pin and reduces the output current. If an input voltage greater than 250mV is applied to the LD then the output current will not change.
The LD pin also provides a simple cost effective solution to soft start. By connecting a capacitor to the LD pin down to ground at initial power up,
the LD pin will be held low, causing the sense threshold to be low. As the capacitor charges up the current sense threshold will increase, thereby
causing the average LED current to increase.
PWM dimming is achieved by applying an external PWM signal to the PWM_D pin. The LED current is proportional to the PWM duty cycle and the
light output can be adjusted between 0 and 100%.The PWM signal enables and disables the AL9901 - modulating the LED current. The ultimate
accuracy of the PWM dimming method is limited only by the minimum gate pulse width, which is a fraction of a percentage of the low frequency
duty cycle. PWM dimming of the LED light can be achieved by turning on and off the converter with a low frequency 50Hz to 1000Hz TTL logic
level signal.
With both modes of dimming it is not possible to achieve average brightness levels higher than the one set by the current sense threshold level of
the AL9901. If a greater LED current is required, then a smaller sense resistor should be used.
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AL9901
Applications Information (cont.)
Output Open Circuit Protection
The non-isolated buck LED driver topology provides inherent protection against an open circuit condition in the LED string due to the LEDs being
connected in series with the inductor. Should the LED string become open circuit then no switching occurs and the circuit can be permanently left
in this state with damage to the rest of the circuit.
AC/DC Off-Line LED Driver
The AL9901 is a cost-effective off-line buck LED driver-converter specifically designed for driving LED strings. It is suitable for being used with
either a rectified AC line or any DC voltage between 15-500V. See figure 3 for typical circuit.
Figure 2 Typical Application Circuit (without PFC)
Buck Design Equations:
VLEDs
D =
VIN
D
tON =
fosc
(VIN − VLEDs )× tON
L ≥
0.3×ILED
0.25
RSENSE
=
Where ILED x 0.3 = IRIPPLE
ILED + (0.5×(ILED ×0.3))
Design Example
For an AC line voltage of 120V the nominal rectified input voltage is VIN = 120V x 1.41 = 169V. From this and the LED chain voltage, the duty
cycle can be determined:
D = VLEDs /VIN = 30/169 = 0.177
From the switching frequency, for example fOSC = 50 kHz, the required on-time of the internal MOSFET can be calculated:
tON = D/fOSC = 3.5 µs
The value of the inductor is determined as follows:
L = (VIN - VLEDs) x tON / (0.3 x ILED) = 4.6mH
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Applications Information (cont.)
Input Bulk Capacitor
For offline lamps, an input bulk capacitor is required to ensure that the rectified AC voltage is held above twice the LED string voltage throughout
the AC line cycle. The value can be calculated from:
P × (1− Dch
)
in
CIN
≥
2 × VLine _min × 2fL × ∆VDC _ max
Where:
Dch : Capacity charge work period, generally about 0.2~0.25
fL : Input frequency for full range (85~265VRMS
Should be set 10~15% of 2VLine _ min
)
∆VDC _ max
If the capacitor has a 15% voltage ripple, then a simplified formula for the minimum value of the bulk input capacitor approximates to:
I
LED × VLEDs × 0.06
2
CMIN
=
V
IN
Power Factor Correction
If power factor improvement is required, then for the input power less than 25W, a simple method for improving the power factor can be
implemented by potential dividing down the rectified mains voltage (resistors R1 and R2 in Figure 4) and feeding it into the LD pin. The current
drawn from the supply voltage will follow an approximate half sine wave. A filter across the LEDs reduces the potential for flicker. This circuit also
significantly reduces the size of input capacitors.
Figure 3 Typical Application Circuit with Simple PFC
Passive power factor correction using three high voltage diodes and two identical capacitors can be implemented. For further design information,
please see AN75 from the Diodes website.
DC-DC Buck LED Driver
The design procedure for an AC input buck LED driver outlined in the previous chapters equally applies to DC input LED drivers.
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AL9901
Applications Information (cont.)
DC-DC Boost LED Driver
Due to the topology of the AL9901 LED driver-converter, it is capable of being used in boost configurations – at reduced accuracy. The accuracy
can be improved by measuring the LED current with an op amp and use the op amp’s output to drive the LD pin.
A Boost LED driver is used when the forward voltage drop of the LED string is higher than the input supply voltage. For example, the Boost
topology can be appropriate when input voltage is supplied by a 48V power supply and the LED string consists of twenty HB LEDs, as the case
may be for a street light.
Figure 4 Boost LED driver
In a Boost converter, when the internal MOSFET is ON the energy is stored in the inductor which is then delivered to the output when the internal
MOSFET switches OFF. If the energy stored in the inductor is not fully depleted by the next switching cycle (continuous conduction mode), the DC
conversion between input and output voltage is given by:
VIN
VOUT − VIN
VOUT
=
ꢀ
D =
1− D
VOUT
From the switching frequency, fOSC, the on-time of the MOSFET can be calculated:
D
tON
=
fOSC
From this the required inductor value can be determined by:
VIN ∗ tON
L =
0.3 ∗ILED
The Boost topology LED driver requires an output capacitor to deliver current to the LED string during the time that the internal MOSFET is on.
In boost LED driver topologies, if the LEDs should become open circuit, damage may occur to the power switch and so some form of detection
should be present to provide overvoltage detection/protection.
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AL9901
Ordering Information
13” Tape and Reel
Part Number
Package Code
Packaging
VCS Tolerance
Quantity
Part Number Suffix
AL9901FDF-13
AL9901S16-13
5%
5%
FDF
S16
U-DFN6040-12
SO-16
3,000/Tape & Reel
2,500/Tape & Reel
-13
-13
Marking Information
PKG
P/N
Marking Code
SOIC-16L
AL9901S16-13
AL9901FDF-13
AL9901
AL9901
DFN6040-12
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AL9901
Package Outline Dimensions (All dimensions in mm.)
Please see AP02002 at http://www.diodes.com/datasheets/ap02002.pdf for the latest version.
(1) U-DFN6040-12
A1
A3
U-DFN6040-12
Dim Min Max Typ
A
Seating Plane
A
A1
A3
b
0.55 0.65 0.60
0
-
0.05 0.02
0.15
D
-
e
0.35 0.45 0.40
5.95 6.05 6.00
D
D1 1.95 2.15 2.05
D2 2.35 2.55 2.45
D2
e
E
-
-
1.00
3.95 4.05 4.00
D1
E2
E
E1
E1 2.10 2.30 2.20
E2 1.80 2.00 1.90
L
L
Z
0.35 0.45 0.40
0.30
-
-
All Dimensions in mm
b
Z
(2) SO-16
SO-16
Dim
A
A1
A2
B
C
D
E
Min
1.40
0.10
1.30
0.33
0.19
9.80
3.80
Max
1.75
0.25
1.50
0.51
0.25
10.00
4.00
H
E
Gauge Plane
θ
L
Detail ‘A’
e
H
L
1.27 Typ
D
A
5.80
0.38
0°
6.20
1.27
8°
A2
θ
All Dimensions in mm
C
e
B
A1
Detail ‘A’
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AL9901
Suggested Pad Layout
Please see AP02001 at http://www.diodes.com/datasheets/ap02001.pdf for the latest version.
(1) U-DFN6040-12
X3
Value
(in mm)
0.500
0.650
0.350
0.250
1.075
1.275
2.750
0.400
1.150
1.000
2.300
Dimensions
Y
C
C
G
G
G1
X
X1
X2
X3
Y
Y3
Y1
Y2
G1
X1
X2
Y1
Y2
Y3
Pin1
X
(2) SO-16
X1
Value
(in mm)
1.270
Dimensions
C
X
0.670
9.560
X1
Y
Y1
1.450
6.400
Y1
Y
Pin 1
C
X
Taping Orientation
The taping orientation of the other package type can be found on our website at http://www.diodes.com/datasheets/ap02007.pdf.
(1) U-DFN6040-12
(2) SOIC-16
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IMPORTANT NOTICE
DIODE INCORPORATED MAKES NO WARRANTY OF ANY KIND, EXPRESS OR IMPLIED, WITH REGARDS TO THIS DOCUMENT,
INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
(AND THEIR EQUIVALENTS UNDER THE LAWS OF ANY JURISDICTION).
Diodes Incorporated and its subsidiaries reserve the right to make modifications, enhancements, improvements, corrections or other changes
without further notice to this document and any product described herein. Diodes Incorporated does not assume any liability arising out of the
application or use of this document or any product described herein; neither does Diodes Incorporated convey any license under its patent or
trademark rights, nor the rights of others. Any Customer or user of this document or products described herein in such applications shall assume
all risks of such use and will agree to hold Diodes Incorporated and all the companies whose products are represented on Diodes Incorporated
website, harmless against all damages.
Diodes Incorporated does not warrant or accept any liability whatsoever in respect of any products purchased through unauthorized sales channel.
Should Customers purchase or use Diodes Incorporated products for any unintended or unauthorized application, Customers shall indemnify and
hold Diodes Incorporated and its representatives harmless against all claims, damages, expenses, and attorney fees arising out of, directly or
indirectly, any claim of personal injury or death associated with such unintended or unauthorized application.
Products described herein may be covered by one or more United States, international or foreign patents pending. Product names and markings
noted herein may also be covered by one or more United States, international or foreign trademarks.
This document is written in English but may be translated into multiple languages for reference. Only the English version of this document is the
final and determinative format released by Diodes Incorporated.
LIFE SUPPORT
Diodes Incorporated products are specifically not authorized for use as critical components in life support devices or systems without the express
written approval of the Chief Executive Officer of Diodes Incorporated. As used herein:
A. Life support devices or systems are devices or systems which:
1. are intended to implant into the body, or
2. support or sustain life and whose failure to perform when properly used in accordance with instructions for use provided in the
labeling can be reasonably expected to result in significant injury to the user.
B. A critical component is any component in a life support device or system whose failure to perform can be reasonably expected to cause the
failure of the life support device or to affect its safety or effectiveness.
Customers represent that they have all necessary expertise in the safety and regulatory ramifications of their life support devices or systems, and
acknowledge and agree that they are solely responsible for all legal, regulatory and safety-related requirements concerning their products and any
use of Diodes Incorporated products in such safety-critical, life support devices or systems, notwithstanding any devices- or systems-related
information or support that may be provided by Diodes Incorporated. Further, Customers must fully indemnify Diodes Incorporated and its
representatives against any damages arising out of the use of Diodes Incorporated products in such safety-critical, life support devices or systems.
Copyright © 2015, Diodes Incorporated
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