A8518 Datasheet, PDF (10/30 Pages) Allegro MicroSystems – Fully integrated 42 V MOSFET for boost converter

A8518 and A8518-1
Wide Input Voltage Range, High-Efficiency,
Fault-Tolerant LED Driver
CHARACTERISTIC PERFORMANCE
Efficiency Measurement
Efficiency at 120mA/Ch for various LED configurations
Efficiency at 120 mA/Channel for various LED configurations
89.00
88.00
87.00
86.00
E^Ef^fff(%%) _85.00
10X2 LED
9X2 LED
84.00
83.00
82.00
8X2 LED
7X2 LED
81.00
80.00
8
10
12
14
16
V^ViInN ⁽(^VV⁾)
A8518 Evaluation Board Efficiency versus Input Voltage while
Disconnect Switch and Snubber Circuit are Used
Startup Waveforms
V_SW
V_OUT
I_LED(TOTAL)
E^Eff^fi^fc^iciⁱe^enⁿc^cyy ^aa^tt^VVⁱⁿ_IN⁼¹=²1^V2^fV^orf^vo^ar^rv^ioa^ur^sio^Lu^Es^{D c}L^oEⁿD^figc^uo^rn^atfi^iogⁿu^srations
90.00
88.00
E_Efff_f(%%) ^86.00
84.00
82.00
9X2 LED
8X2 LED
7X2 LED
80.00
78.00
0.1
0.2
0.3
0.4
T^To^ot^aa^ll^LL^Ee^Dd C^Cu^ur^reeⁿn^tt⁽(^AA⁾)
A8518 Evaluation Board Efficiency versus Total LED Current while
Disconnect Switch and Snubber Circuit are Used
Higher efficiency can be achieved by:
• Using an inductor with a low DCR.
• Using lower forward voltage drop and a smaller juction
capacitance Schottky diode.
• Removal of snubber circuit; however, this might compromise
the EMI performance.
• Shorting out the disconnect switch and the input current sense
resistor; however, this will eliminate the output short-to-GND
protection feature.
Start up at 100% PWM Dimming, V_IN = 7 V, 2 Channels,
10 LEDs/Channels, 120 mA/Channels; Time base = 10 ms/Div
V_SW
V_OUT
I_LED(TOTAL)
Start up at 0.02% PWM Dimming at 200 Hz, V_IN = 7 V, 2 Channels,
10 LEDs/Channel, 120 mA/Channel; Time base = 10 ms/Div
Allegro MicroSystems, LLC
10
115 Northeast Cutoff
Worcester, Massachusetts 01615-0036 U.S.A.
1.508.853.5000; www.allegromicro.com