AL9910ASP-13 Diodes Inc, AL9910ASP-13 Datasheet - Page 6

• Manufacturer Part Number: AL9910ASP-13
• Description: LED Drivers 300kHz 85 to 277Vac 7.5V Mosfet LED
• Manufacturer: Diodes Inc
• Series: -r

Specifications of AL9910ASP-13

• Constant Current: Yes
• Constant Voltage: -
• Topology: AC DC Offline Switcher, PWM
• Number Of Outputs: 1
• Internal Driver: No
• Type - Primary: Backlight, General Purpose
• Type - Secondary: High Brightness LED (HBLED)
• Frequency: 25kHz ~ 300kHz
• Voltage - Supply: 85 V ~ 277 VAC
• Voltage - Output: 10V
• Mounting Type: Surface Mount
• Package / Case: 8-SOIC (0.154", 3.90mm Width) Exposed Pad
• Operating Temperature: -40°C ~ 85°C
• Lead Free Status / Rohs Status: Details

Applications 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.
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 V
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 (R
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:
AL9910/AL9910A
Document number: DS 35103 Rev. 2 - 2
V
V
R
DD
DD
SENSE
=
V
V
IN
IN
(
I
LED
PWM_D
PWM_D
+
0 (
250
V
V
5 .
V
V
LD
LD
DD
DD
IN
IN
mV
I *
RIPPLE
250mV
250mV
GND
GND
))
LDO
LDO
100k
100k
)
Figure 1. Functional block diagram
.
OTP
OTP
UNIVERSAL HIGH VOLTAGE HIGH BRIGHTNESS LED
AL9910/AL9910A
AL9910/AL9910A
www.diodes.com
7.5/10V
7.5/10V
6 of 14
S
S
R
R
SENSE
O
O
OSC
OSC
). When the voltage across R
R
R
GATE
GATE
CS
CS
AL9910/AL9910A
OSC
OSC
R
R
SENSE
SENSE
SENSE
© Diodes Incorporated
March 2011
exceeds the
DRIVER
IN
pin.