A6210GEUTR-T Allegro Microsystems Inc, A6210GEUTR-T Datasheet - Page 7

• Manufacturer Part Number: A6210GEUTR-T
• Description: IC LED DRIVER HIGH BRIGHT 16-QFN
• Manufacturer: Allegro Microsystems Inc
• Type: HBLED Driverr

Specifications of A6210GEUTR-T

• Topology: PWM, Step-Down (Buck), Switched Capacitor (Charge Pump)
• Number Of Outputs: 1
• Internal Driver: Yes
• Type - Secondary: High Brightness LED (HBLED)
• Frequency: 100kHz ~ 2 MHz
• Voltage - Supply: 9 V ~ 46 V
• Voltage - Output: 46V
• Mounting Type: Surface Mount
• Package / Case: 16-WSQFN Exposed Pad
• Operating Temperature: -40°C ~ 105°C
• Current - Output / Channel: 3A
• Internal Switch(s): Yes
• Efficiency: 90%
• Led Driver Application: Power Supplies And Lamps
• No. Of Outputs: 1
• Output Current: 3A
• Output Voltage: 46V
• Input Voltage: 9V To 46V
• Dimming Control Type: PWM
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant
• Other names: 620-1281-2

A6210
off-time of 350 ns. A minimum off-time is required to ensure the
bootstrap supply operates correctly. It can be shown that:
where t
Therefore:
The t
Choose R1 = 180 kΩ.
The inductor (L1) can now be found using the target LED ripple
current of 60 mA:
Choose L1 = 68 μH.
The inductor current rating should exceed the average current
plus half of the ripple current. In addition, it is recommended that
on
off
resistor (R1) value can be found:
R
is 350 ns maximum.
L
1
1
=
=
=
=
V
12 × 2.051 × 10
(V
60 × 10
LED
IN
(24 – 12) × 0.51
I
RIPPLE
– V
× 2.051 × 10
1.4 × 10
f
f
SW
SW
LED
–3
f
SW
× f
=
=
) × D
× 1.4 × 10
SW
t
350 × 10
1 – 0.51
off
6
1 – D
(min)
10
10
6
–9
=
=
,
176 × 10
=
72 × 10
1.4 MHz
3
–6
.
.
3 A, 2 MHz Buck-Regulating LED Driver
.
(10)
(8)
(9)
a margin of at least 20% be allowed. In this example, the inductor
current rating, I
The valley control current is simply the average LED current
minus half the ripple current. Therefore:
The sense resistor (R3) value can be found:
Choose R3 = 390 mΩ.
The ripple voltage developed across the sense resistor (R2) is
60 mA × 390 mΩ = 23 mV, which is greater than the minimum
required value of 20 mV.
Measured switching waveforms
From figure 3, it can be seen that the average current through
the LED string is 484 mA. This represents an error of 3.2% with
respect to the target current of 500 mA.
I
L
R
≥ 1.2 × (500 × 10
I
VALLEY
3
=
=
L
V
I
183 × 10
470 × 10
VALLEY
, should be:
=
=
SENSE
500 × 10
I
av
–
–3
–3
I
RIPPLE
2
115 Northeast Cutoff
1.508.853.5000; www.allegromicro.com
Allegro MicroSystems, Inc.
Worcester, Massachusetts 01615-0036 U.S.A.
–3
=
–3
+ 60 × 10
–
0.36
60 × 10
2
–3
.
–3
/ 2) = 636 mA .
=
470 mA
.
(12)
(11)
7