AL9910A-5SP-13 [DIODES]
LED Driver,;
| 型号： | AL9910A-5SP-13 |
| 厂家： | 
DIODES INCORPORATED |
| 描述： | LED Driver, 驱动 接口集成电路 |
| 文件： | 总15页 (文件大小：342K) |
| 中文： | 中文翻译 | 下载： | 下载PDF数据表文档文件 |
AL9910/ AL9910A/ AL9910-5/ AL9910A-5
UNIVERSAL HIGH VOLTAGE HIGH BRIGHTNESS LED DRIVER
Description
Pin Assignments
(Top View)
The AL9910/A high voltage PWM LED driver-controller provides an
efficient solution for offline high brightness LED lamps from rectified
line voltages ranging from 85VAC up to 277VAC. The AL9910 drives
external MOSFETs at switching frequencies up to 300kHz, with the
switching frequency determined by a single resistor. The AL9910
topology creates a constant current through the LEDs providing
constant light output. The output current is programmed by one
external resistor and is ultimately determined by the external
MOSFET chosen and therefore allows many low current LEDs to be
driven as well as a few high current LEDs.
ROSC
LD
1
2
8
7
6
5
VIN
CS
AL9910
VDD
GND 3
4
GATE
PWM_D
SO-8
(Top View)
The LED brightness can be varied by both Linear and PWM dimming
using the AL9910’s LD and PWM_D pins respectively. The PWM_D
input operates with duty ratio of 0-100% and frequency of up to
several kHz.
ROSC
LD
1
2
8
7
6
5
VIN
CS
AL9910
VDD
GND 3
The AL9910 can withstand input voltages up to 500V which makes it
very resilient to transients at standard mains voltages. As well as
standard SO-8 package the AL9910 is available in the thermally
enhanced SO-8EP package.
4
GATE
PWM_D
SO-8EP
Applications
Features
•
•
•
•
•
LED Offline Lamps
•
•
•
•
>90% Efficiency
High Voltage DC-DC LED Driver
Signage and Decorative LED Lighting
Back Lighting of Flat Panel Displays
Universal Rectified 85 to 277VAC Input Range
Input Voltage Up to 500V
Internal Voltage Regulator Removes Start-Up Resistor
General Purpose Constant Current Source
7.5V MOSFET Drive – AL9910
10V MOSFET Drive – AL9910A
•
•
•
•
•
•
•
Tighter Current Sense Tolerance: 5% AL9910-5, AL9910A-5
Drives LED Lamps with Both High and Low Current LEDs
LED Brightness Control with Linear and PWM Dimming
Internal Thermal Protection (OTP)
Available in SO-8 and SO-8EP Packages
Totally Lead-Free & Fully RoHS Compliant (Notes 1 & 2)
Halogen and Antimony Free. “Green” Device (Note 3)
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/quality/lead_free.html 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.
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AL9910/ AL9910A/ AL9910-5/ AL9910-5A
Document number: DS35103 Rev. 9 - 2
AL9910/ AL9910A/ AL9910-5/ AL9910A-5
Typical Applications Circuit
C3
D1
VIN
L1
VAC IN
VDD
LD
C1
Q1
AL9910/A
BR1
GATE
C2
CS
PWM_D
ROSC
RSENSE
GND
ROSC
Pin Descriptions
Pin Number
Pin
Name
Function
SO-8
SO-8EP
Input Voltage
1
2
3
4
5
1
2
3
4
5
VIN
CS
Senses LED string and external MOSFET switch current
Device Ground
GND
Gate
Drives the gate of the external MOSFET switch.
PWM_D
Low Frequency PWM Dimming pin, also Enable input. Internal 200kΩ pull-down to GND.
Internally regulated supply voltage.
7.5V nominal for AL9910 and AL9910-5
10V nominal for AL9910A.
6
7
6
7
VDD
LD
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.
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 sets the PWM frequency. The devices
can be switched into constant off time (PFM) mode by connecting the external oscillator resistor between
ROSC pin and the gate of the external MOSFET.
8
8
ROSC
EP PAD
N/A
EP
Exposed Pad (bottom). Connect to GND directly underneath the package.
Functional Block Diagram
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AL9910/ AL9910A/ AL9910-5/ AL9910-5A
Document number: DS35103 Rev. 9 - 2
AL9910/ AL9910A/ AL9910-5/ AL9910A-5
Absolute Maximum Ratings (Note 4) (@TA = +25°C, unless otherwise specified.)
Symbol
VIN(MAX)
VCS
Parameter
Ratings
-0.5 to +520
-0.3 to +0.45
-0.3 to (VDD +0.3)
-0.3 to (VDD +0.3)
-0.3 to (VDD +0.3)
12
Unit
V
Maximum Input Voltage, VIN, to GND
Maximum CS Input Pin Voltage Relative to GND
Maximum LD Input Pin Voltage Relative to GND
Maximum PWM_D Input Pin Voltage Relative to GND
Maximum GATE Pin Voltage Relative to GND
V
V
VLD
V
VPWM_D
VGATE
VDD(MAX)
V
V
Maximum VDD Pin Voltage Relative to GND
Continuous Power Dissipation (TA = +25°C)
SO-8 (derate 6.3mW/°C above +25°C)
SO-8EP (derate at 22mW/°C above 25°C)
Junction Temperature Range
630
2200
+150
mW
mW
°C
TJ
Storage Temperature Range
-65 to +150
1500
°C
V
TST
ESD HBM
ESD MM
Human Body Model ESD Protection (Note 5)
Machine Model ESD Protection (Note 5)
300
V
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
Recommended Operating Conditions (@TA = +25°C, unless otherwise specified.)
Symbol
Parameter
Min
Max
Unit
AL9910
AL9910-5
15.0
500
Input DC Supply Voltage Range
V
VINDC
AL9910A
Al9910A-5
20.0
500
AL9910_S
-40
-40
+85
Ambient Temperature Range (Note 6)
°C
V
TA
AL9910_SP
+105
AL9910
AL9910-5
10
12
VDD
Maximum Recommended Voltage Applied to VDD Pin (Note 7)
AL9910A
AL9910A-5
Pin PWM_D Input Low Voltage
Pin PWM_D Input High Voltage
0
1
VEN(LO)
VEN(HI)
Notes:
V
2.4
VDD
6. Maximum ambient temperature range is limited by allowable power dissipation. The Exposed pad SO-8EP with its lower thermal impedance allows
the variants using this package to extend the allowable maximum ambient temperature range.
7. When using the AL9910 in isolated LED lamps an auxiliary winding might be used.
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AL9910/ AL9910A/ AL9910-5/ AL9910-5A
Document number: DS35103 Rev. 9 - 2
AL9910/ AL9910A/ AL9910-5/ AL9910A-5
Electrical Characteristics (@TA = +25°C, unless otherwise specified.)
Symbol
Parameter
Conditions
Pin PWM_D to GND,
VIN = VIN(MIN) (Note 6)
Min
Typ
0.50
0.65
7.5
Max
1
Unit
AL9910
AL9910-5
Shut-Down Mode Supply Current
mA
IINSD
AL9910A
1.2
8.0
11
AL9910
AL9910-5
7.0
9
VIN = VIN(MIN) ~500V, (Note 8)
Internally Regulated Voltage
V
mA
V
VDD
lDD(ext) = 0, Gate pin open
AL9910A
10
VDD Current Available for External
Circuitry
1.0
IDD(ext)
UVLO
VIN = VIN(MIN) to 100V (Notes 8 & 9)
AL9910
AL9910-5
6.4
8
6.7
9
7
V
DD Under Voltage Lockout Threshold VDD rising
AL9910A
10
AL9910
AL9910-5
500
∆UVLO
mV
VDD Under Voltage Lockout Hysteresis VDD falling
AL9910A
750
200
250
PWM_D Pull-Down Resistance
150
225
250
275
kΩ
RPWM_D
VPWM_D = 5V
AL9910
230
242
255
280
267
AL9910A
Full ambient temperature range
(Note 10)
Current Sense Threshold Voltage
mV
VCS(HI)
255
250
AL9910A-5
AL9910-5
237.5
VDD -0.3
0
262.5
VDD
0.3
GATE High Output Voltage
GATE Low Output Voltage
V
V
VGATE(HI)
VGATE(LO)
IOUT = 10mA
IOUT = -10mA
ROSC = 1MΩ
ROSC = 226kΩ
20
25
30
Oscillator Frequency
kHz
%
fOSC
80
100
120
fPWMhf = 25kHz, at GATE,
CS to GND.
Maximum Oscillator PWM Duty Cycle
100
DMAXhf
Full ambient temperature range (Note 10),
VIN = 20V
Linear Dimming Pin Voltage Range
Current Sense Blanking Interval
Delay From CS Trip to GATE lo
0
-
250
440
300
mV
ns
VLD
160
250
tBLANK
tDELAY
VCS = 0.45V, VLD = VDD
V
IN = 20V, VLD = 0.15,
ns
VCS = 0 to 0.22V after TBLANK
CGATE = 500pF
GATE Output Rise Time
GATE Output Fall Time
Thermal Shut Down
30
50
50
ns
ns
tRISE
tFALL
TSD
30
150
50
CGATE = 500pF
°C
Thermal Shut Down Hysteresis
TSDH
SO-8 (Note 11)
SO-8EP (Note 12)
SO-8 (Note 11)
SO-8EP (Note 12)
110
66
Thermal Resistance Junction-to-
Ambient
θJA
θJC
°C/W
°C/W
22
Thermal Resistance Junction-to-Case
9
Notes:
8. VIN(MIN) for the AL9910 is 15V and for the AL9910A it is 20V.
9. Also limited by package power dissipation limit, whichever is lower.
10. Full ambient temperature range for AL9910-5S, AL9910AS and AL9910S is -40 to +85°C; for AL9910-5SP, AL9910ASP and AL9910SP is
-40°C to +105°C.
11. 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.
12. Device mounted on FR-4 PCB (51mm x 51mm 2oz copper, minimum recommended pad layout on top layer and thermal vias to bottom layer ground
plane. For better thermal performance, larger copper pad for heat-sink is needed.
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AL9910/ AL9910A/ AL9910-5/ AL9910-5A
Document number: DS35103 Rev. 9 - 2
AL9910/ AL9910A/ AL9910-5/ AL9910A-5
Typical Characteristics
3.0
2.5
2.0
1.5
460
440
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
60
85
-40
-15
10
35
60
85
AMBIENT TEMPERATURE (°C)
AMBIENT TEMPERATURE (°C)
Change in Current Sense Threshold vs. Ambient Temperature
100
Input Current vs. Ambient Temperature
450
400
I
= 281mA
I
= 180mA
LED
LED(NOM)
90
80
70
60
V
T
= 264V
IN
= 23.5C
A
350
300
250
50
40
30
20
200
150
10
0
0
50
100
150
200
250
300
85 105 125 145 165 185 205 225 245 265
INPUT VOLTAGE (VRMS
180mA LED Driver Short Circuit Output Current vs. Input Voltage
VLD DIMMING CONTROL (mV)
IOUT MAX vs. VLD Dimming Control
)
1.5
1.0
0.5
0.0
R
= 226kΩ
OSC
-0.5
-1.0
R
= 1MΩ
OSC
-1.5
-2.0
-40
-15
10
35
60
85
AMBIENT TEMPERATURE (°C)
Change in Oscillation Frequency vs. Ambient Temperature
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AL9910/ AL9910A/ AL9910-5/ AL9910-5A
Document number: DS35103 Rev. 9 - 2
AL9910/ AL9910A/ AL9910-5/ AL9910A-5
Typical Characteristics (cont.) measured using AL9910EV4
200
95
15 LEDs
14 LEDs
190
180
18 LEDs
90
17 LEDs
16 LEDs
170
14 LEDs
17 LEDs
16 LEDs
160
150
85
15 LEDs
18 LEDs
140
80
85 105 125 145 165 185 205 225 245 265
INPUT VOLTAGE (VRMS
180mA LED Driver Output Current vs. Input Voltage
85 105 125 145 165 185 205 225 245 265
)
INPUT VOLTAGE (VRMS
)
180mA LED Driver Efficiency 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
85 105 125 145 165 185 205 225 245 265
INPUT VOLTAGE (VRMS
180mA LED Driver Input Power Dissipation vs. Input Voltage
)
)
180mA LED Driver Power Factor vs. Input Voltage
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AL9910/ AL9910A/ AL9910-5/ AL9910-5A
Document number: DS35103 Rev. 9 - 2
AL9910/ AL9910A/ AL9910-5/ AL9910A-5
Application Information
The AL9910 is very versatile and 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.
VIN
VIN
VDD
7.5/10V
ROSC
LDO
OSC
VDD
250mV
S
R
GATE
CS
O
LD
OTP
RSENSE
PWM_D
100k
GND
AL9910/AL9910A
Figure 1 Functional Block Diagram
The AL9910 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 external 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 external
MOSFET Q1 is turned off. The stored energy in the inductor causes the current to continue to flow through the LEDs via diode D1.
The AL9910’s LDO provides all power to the rest of the IC including Gate drive this removes the need for large high power start-up resistors. This
means that operate correctly it 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 AL9910 operates and regulates by limiting the peak current of the external MOSFET; the peak current sense threshold is nominally set at
250mV.
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 external MOSFET.
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 2 - 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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AL9910/ AL9910A/ AL9910-5/ AL9910-5A
Document number: DS35103 Rev. 9 - 2
AL9910/ AL9910A/ AL9910-5/ AL9910A-5
Applications Information (cont.)
Setting Operating Frequency
The AL9910 is capable of operating over a 25 and 300 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
When driving smaller numbers of LEDs, 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 2 times the forward voltage
drop across the LEDs. This limitation is related to the output current instability that may develop when the AL9910 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.
The best solution is to adopt the so-called constant off-time operation as shown in Figure 2. The resistor (ROSC) is, connected to ground by
default, to set operating frequency. To force the AL9910 to enter constant OFF time mode ROSC is connected to the gate of the external MOSFET.
This will decrease the duty cycle from 50% by increasing the total period, tOFF + tON
.
VIN
VDD
LD
VIN
Q1
AL9910/A GATE
CS
PWM_D
ROSC
GND
ROSC
Figure 2. Constant Off-Time Configuration
The oscillator period equation above now defines the AL9910 off time, tOFF
.
When using this mode the nominal switching frequency is chosen and from the nominal input and output voltages the off-time can be calculated:
⎛
⎞
⎟
VOUT(nom)
1
⎜
tOFF = 1−
∗
⎜
⎝
⎟
⎠
V
fOSC
IN(nom)
From this the timing resistor, ROSC, can be calculated: ROSC
=
tOFF(µs)∗25 − 22(kΩ)
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.
(
V
− VLEDs
)
× D
IN
L =
Where D is duty cycle
(
0.3 ×ILED
)
× fOSC
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.
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AL9910/ AL9910A/ AL9910-5/ AL9910-5A
Document number: DS35103 Rev. 9 - 2
AL9910/ AL9910A/ AL9910-5/ AL9910A-5
Applications Information (cont.)
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_D pin to ground will turn off the AL9910. When disabled, the AL9910’s quiescent current is
typically 0.5mA (0.65 for AL9910A). 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_D pin will turn off the power transistor.
Linear dimming is accomplished by applying a 45mV 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 zero and 100%. The PWM signal enables and disables the AL9910 - 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 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 AL9910. If a greater LED current is required then a smaller sense resistor should be used
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 AL9910 is a cost-effective off-line buck LED driver-controller specifically designed for driving LED strings. It is suitable for being used with
either rectified AC line or any DC voltage between 15V to 500V. See Figure 3 for typical circuit.
LED +
C3
D1
VIN
L1
VAC IN
VDD
LD
C1
LED -
C2
Q1
AL9910/A GATE
BR1
CS
PWM_D
ROSC
GND
RSENSE
ROSC
Figure 3. Typical Application Circuit (without PFC)
Buck Design Equations:
VLEDs
D =
tON
L ≥
V
IN
D
=
fosc
(VIN − VLEDs)× tON
0.3×ILED
0.25
ILED + (0.5×(ILED × 0.3))
RSENSE
=
where ILED x 0.3 = IRIPPLE
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AL9910/ AL9910A/ AL9910-5/ AL9910-5A
Document number: DS35103 Rev. 9 - 2
AL9910/ AL9910A/ AL9910-5/ AL9910A-5
Applications Information (cont.)
Design Example
For an AC line voltage of 120V the nominal rectified input voltage VIN = 120V*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 = 50kHz, the required on-time of the external MOSFET can be calculated:
t
ON = D/fOSC = 3.5 µs
The value of the inductor for an LED current of 350mA is determined as follows:
L = (VIN - VLEDs) * tON /(0.3 * ILED) = 4.6mH
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 ×ΔVDC_MAX
Where
Dch : Capacity charge work period, generally about 0.2 to 0.25
fL : Input frequency for full range (85 to 265VRMS
Should be set 10 to15% of 2VLINE _ MIN
)
ΔVDC _ MAX
If the capacitor has a 15% voltage ripple then a simplified formula for the minimum value of the bulk input capacitor approximates to:
ILED × VLEDs × 0.06
CMIN
=
2
V
IN
Power Factor Correction
If power factor improvement is required then for the input power less than 25W, a simple passive power factor correction circuit can be added to
the AL9910 typical application circuit. Figure 4 shows that passive PFC circuitry (3 current steering diodes and 2 identical capacitors) does not
significantly affect the rest of the circuit. Simple passive PFC improves the line current harmonic distortion and achieves a power factor greater
than 0.85.
Passive PFC
LED +
C4
C1
D1
VIN
VAC IN
VDD
LD
LED -
Q1
L1
AL9910/A GATE
BR1
CS
PWM_D
ROSC
GND
C2
C3
RSENSE
ROSC
Figure 4. Typical Application Circuit with Passive PFC
Each of these identical capacitors should be rated for half of the input voltage and have twice as much capacitance as the calculated CMIN of the
buck converter circuit without passive PFC (see above section on bulk capacitor calculation).
For further design information please see AN75 from the Diodes website.
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AL9910/ AL9910A/ AL9910-5/ AL9910-5A
Document number: DS35103 Rev. 9 - 2
AL9910/ AL9910A/ AL9910-5/ AL9910A-5
Applications Information (cont.)
DC-DC Buck LED Driver
The design procedure for an ac input buck LED driver outlined in the previous chapters equally applies DC input LED drivers.
When driving long LED chains care should be taken not to induce SBO – maximum LED chain voltage should be less half of VIN. So either
maximum duty cycle should be kept below 50% or use of constant off-time removes this issue.
DC-DC Boost LED Driver
Due to the topology of the AL9910 LED driver-controller 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.
L1
VIN
D1
VDD
C1
Q1
AL9910/A
VIN
PWM_D
GATE
C2
C3
LD
CS
ROSC
GND
ROSC
RSENSE
Figure 5. Boost LED Driver
In a Boost converter, when the external MOSFET is ON the energy is stored in the inductor which is then delivered to the output when the external
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:
VOUT − V
VIN
IN
D =
Î
VOUT
=
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:
V
IN ∗ 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 external 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 Over-voltage detection/protection.
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AL9910/ AL9910A/ AL9910-5/ AL9910-5A
Document number: DS35103 Rev. 9 - 2
AL9910/ AL9910A/ AL9910-5/ AL9910A-5
Ordering Information
XX
AL9910
XX - 13
X
VCS Tolerance
Variant
Package
Packing
Blank : 10%
-5 : 5%
Blank : 7.5V VDD
A : 10V VDD
S : SO-8
SP : SO-8EP
13 : 13” Tape & Reel
13” Tape and Reel
Package
Code
Part Number
Packaging
VCS Tolerance
Quantity
Part Number Suffix
AL9910-5S-13
AL9910-5SP-13
AL9910A-5S-13
AL9910A-5SP-13
AL9910AS-13
AL9910ASP-13
AL9910S-13
±5%
±5%
S
SO-8
SO-8EP
SO-8
2500/Tape & Reel
2500/Tape & Reel
2500/Tape & Reel
2500/Tape & Reel
2500/Tape & Reel
2500/Tape & Reel
2500/Tape & Reel
2500/Tape & Reel
-13
-13
-13
-13
-13
-13
-13
-13
SP
S
±5%
±5%
SP
S
SO-8EP
SO-8
±10%
±10%
±10%
±10%
SP
S
SO-8EP
SO-8
AL9910SP-13
SP
SO-8EP
Marking Information
(1) SO-8
(Top View)
8
7
6
5
4
Logo
Part Number
9910 for 7.5V, 10%
9910-5 for 7.5V, 5%
9910A for 10V, 10%
9910A5 for 10V, 5%
YY : Year : 08, 09,10~
WW : Week : 01~52; 52
represents 52 and 53 week
X X : Internal Code
9910 XX
YY WW X X
2
3
1
(2) SO8-EP
(Top View)
8
7
6
5
Logo
YY : Year : 08, 09,10~
WW : Week : 01~52; 52
Part Number
9910 X X
YY WW X X E
represents 52 and 53 week
9910 for 7.5V, 10%
9910-5 for 7.5V, 5%
9910A for 10V, 10%
9910A5 for 10V, 5%
X X : Internal Code
E : SO-8EP
2
3
4
1
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AL9910/ AL9910A/ AL9910-5/ AL9910-5A
Document number: DS35103 Rev. 9 - 2
AL9910/ AL9910A/ AL9910-5/ AL9910A-5
Package Outline Dimensions (All dimensions in mm.)
Please see AP02002 at http://www.diodes.com/datasheets/ap02002.pdf for latest version.
(1) SO-8
SO-8
Min
-
0.10
1.30
0.15
0.3
Dim
A
A1
A2
A3
b
Max
1.75
0.20
1.50
0.25
0.5
E1
E
Gauge Plane
Seating Plane
A1
L
D
E
E1
e
h
L
θ
4.85
5.90
3.85
1.27 Typ
-
0.62
0°
4.95
6.10
3.95
Detail ‘A’
7°~9°
h
°
45
0.35
0.82
8°
Detail ‘A’
A2
A3
A
b
e
All Dimensions in mm
D
(2) SO-8EP
Exposed Pad
SO-8EP (SOP-8L-EP)
Dim Min Max Typ
8
1
5
4
A
1.40 1.50 1.45
E1
A1 0.00 0.13
-
H
b
C
D
E
0.30 0.50 0.40
0.15 0.25 0.20
4.85 4.95 4.90
3.80 3.90 3.85
F
E0 3.85 3.95 3.90
E1 5.90 6.10 6.00
b
Bottom View
E
e
F
H
L
-
-
1.27
9° (All sides)
N
2.75 3.35 3.05
2.11 2.71 2.41
0.62 0.82 0.72
45°
7°
Q
C
4° ± 3°
A
Gauge Plane
Seating Plane
N
Q
-
-
0.35
e
E0
A1
0.60 0.70 0.65
L
D
All Dimensions in mm
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AL9910/ AL9910A/ AL9910-5/ AL9910-5A
Document number: DS35103 Rev. 9 - 2
AL9910/ AL9910A/ AL9910-5/ AL9910A-5
Suggested Pad Layout
Please see AP02001 at http://www.diodes.com/datasheets/ap02001.pdf for the latest version.
(1) SO-8
X
Dimensions Value (in mm)
X
Y
C1
C2
0.60
1.55
5.4
C1
1.27
C2
Y
(2) SO-8EP
X2
Value
Dimensions
(in mm)
1.270
0.802
3.502
4.612
1.505
2.613
6.500
C
X
X1
X2
Y
Y1
Y2
X1
Y1
Y2
Y
C
X
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AL9910/ AL9910A/ AL9910-5/ AL9910-5A
Document number: DS35103 Rev. 9 - 2
AL9910/ AL9910A/ AL9910-5/ AL9910A-5
IMPORTANT NOTICE
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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).
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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
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Customers represent that they have all necessary expertise in the safety and regulatory ramifications of their life support devices or systems, and
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Copyright © 2014, Diodes Incorporated
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Document number: DS35103 Rev. 9 - 2
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