AP8800AWT-7 Diodes Inc, AP8800AWT-7 Datasheet - Page 6

• Manufacturer Part Number: AP8800AWT-7
• Description: LED Drivers 28V 1-W LED Driver DC/DC Converter
• Manufacturer: Diodes Inc
• Series: -r

Specifications of AP8800AWT-7

• Constant Current: Yes
• Constant Voltage: -
• Topology: PWM, Step-Down (Buck)
• Number Of Outputs: 1
• Internal Driver: Yes
• Type - Primary: General Purpose
• Type - Secondary: -
• Frequency: 600kHz
• Voltage - Supply: 8 V ~ 28 V
• Voltage - Output: -
• Mounting Type: Surface Mount
• Package / Case: SOT-23-5 Thin, TSOT-23-5
• Operating Temperature: -40°C ~ 105°C
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant

Applications Information
LED Current Control
The LED current is controlled by the resistor R
With the CTRL pin left floating and the external current sense resistor, R
and SET, the nominal average output current in the LEDs is:
If the CTRL pin is driven by an external voltage (lower than 2.5V), the average LED current in this case is:
The graph in figure 2 gives values of nominal average output current for several values of current setting resistor (R
typical application circuit shown on Figure 1, for different voltages applied on the CTRL pin.
AP8800A
Document number: DS35100 Rev. 2 - 2
I
I
LED
LED
=
=
R
V
V
V
400
350
300
250
200
150
100
Vsupply
THD
SET
CTRL
50
REF
0
0
0.15 0.3 0.45 0.6 0.75 0.9 1.05 1.2 1.35 1.5 1.65 1.8 1.95 2.1 2.25 2.4 2.55 2.7 2.85
R
V
THD
SET
where V
0.3
0.3
0.33
D2
D4
0.39
0.39
THD
0.47
0.47
0.56
0.56
0.56
is nominally 1.25V
0.68
0.68
0.68
0.75
(T
0.82
0.82
0.82
Figure 2. LED Current setting Vs R
A
D5
D3
= 25°C unless otherwise stated)
1
1
Figure 1. MR16 Typical configuration
1
LED current Versus RSET and VCTRL
SET
RSET value [Ohms]
1.2
1.2
1.2
C1
in Figure 1.
www.diodes.com
1.5
1.5
1.5
COST EFFECTIVE 28V BUCK 1-W LED DRIVER
C3
D1
6 of 12
U1
AP8800A
R
2
2
2
SET
SET
SET
(greater than 0.3 Ω) is connected between V
and V
CTRL
L1
C2
3
3
3
3
AP8800A
LED current @
VCTRL = 1.25V
LED current @
VCTRL = 2.5V
LED current @
VCTRL = 0.625V
© Diodes Incorporated
January 2011
SET
) in the
IN