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| 型号： | A6281EESTR-T |
| 厂商： | Allegro Microsystems Inc |
| 文件页数： | 6/11页 |
| 文件大小： | 0K |
| 描述： | IC LED DRIVER PWM CONTROL 16-QFN |
| 产品培训模块： | A6281 Three-channel LED Driver |
| 标准包装： | 1,500 |
| 恒定电流： | 是 |
| 拓扑： | 线性，PWM |
| 输出数： | 3 |
| 内部驱动器： | 是 |
| 类型 - 次要： | RGB |
| 频率： | 5MHz |
| 电源电压： | 4.75 V ~ 17 V |
| 输出电压： | 1 V ~ 3 V |
| 安装类型： | 表面贴装 |
| 封装/外壳： | 16-WFQFN 裸露焊盘 |
| 供应商设备封装： | 16-QFN/MLP 裸露焊盘（3x3） |
| 包装： | 带卷 (TR) |
| 工作温度： | -40°C ~ 85°C |
| 产品目录页面： | 1141 (CN2011-ZH PDF) |
| 其它名称： | 620-1218-2 |
A6281
3-Channel Constant Current LED Driver
with Programmable PWM Control
Functional Description
Shift Register
The A6281 has a 32-bit shift register that loads data through the
SDI (serial data in) pin. The shift register operates by a first-in
first-out (FIFO) method. The most significant bit (MSB, bit 31)
is the first bit shifted in and the least significant bit (LSB, bit 0)
is shifted in last. The serial data is clocked by a rising edge of the
CI (clock in) pin. The SDO (serial data out) pin is updated to the
state of bit 31 on the falling edge of the CI pin. This will prevent
any race conditions and erroneous data that might occur while
propagating information through multiple A6281s that are daisy
chained together. The contents of the shift register will continue
to propagate on every rising edge of the CI pin. The information
in the shift register is latched on a low-to-high transition of the LI
(Latch In) pin. The LI pin must be brought low before the rising
edge of the next clock pulse, to avoid latching erroneous data.
The latched data remains latched on a rising signal on the OEI
(output enable in) pin.
Output Buffers
The A6281 is designed to allow daisy chaining many A6281s
together. It can pass the clock, data, latch, and output enable
signals from one A6821 to the next without any loss of data due
to duty cycle skewing or signal degradation.
The A6821 is equipped with output buffers that allow the data
signals to travel over long distances through strings of A6281s
without the need for extra driving hardware. The A6281 drives
these signals to TTL levels. Each of the A6281 inputs has a cor-
responding buffered output:
? CI (clock in) pin to CO (clock out) pin
? LI (latch in) pin to LO (latch out) pin
? OEI (output enable in) pin to OEO (output enable out) pin
? SDI (serial data in) pin to SDO (serial data out) pin
The CO (clock out) pin is driven by an internal one-shot circuit.
When the CI pin detects an edge rising through the input thresh-
old, the one-shot circuitry drives the CO pin high for 100 ns. The
CI pin input threshold has hysteresis to prevent false triggering
of the CO signal. The implementation of the one-shot solution
allows many A6281s to be daisy chained together with a consis-
tent clock signal throughout the entire chain without degradation
or loss of synchronicity to the data line.
PWM Brightness Control
The A6281 controls the intensity of each LED by pulse width
modulating the current of each output. The A6281 has three
10-bit brightness registers, one for each output. These brightness
registers set the PWM count value at which the outputs switch
off during each PWM cycle. Each 10-bit brightness register gives
1023 levels of light intensity. The duty cycle, DC, can be deter-
mined by the following equation:
DC = [(PWM n + 1) / 1024] ×100 (%) ,
where PWM n is the PWM value greater than zero that is stored in
the brightness register.
SDI
Shift Register
0 to 6
7 to 8
9
10 to 16
17 to 19
20 to 26
27
28 to 29
30
31
SDO
CI
LI
Latched Registers
100 ns
One-Shot
CO
LO
Current Clock
Scalar 0 Mode
7 Bits 2 Bits
Unused
1 Bit
Current
Scalar 1
7 Bits
Unused
3 Bits
Current
Scalar 2 Unused
7 Bits 1 Bit
Test
Bits
‘’00”
Address
Bit
“1”
Unused
1 Bit
800 kHz
PWM Counter 0
10 Bits
PWM Counter 1
10 Bits
PWM Counter 2
10 Bits
Address
Bit
“0”
Unused
1 Bit
OEI
OEO
R EXT
REXT
VIN
+5V
Regulator
Current
Regulator 0
Current
Regulator 1
Current
Regulator 2
VREG
OUT0
OUT1
OUT2
PGND
LGND
Figure 4. Functional Diagram
Allegro MicroSystems, LLC
115 Northeast Cutoff
Worcester, Massachusetts 01615-0036 U.S.A.
1.508.853.5000; www.allegromicro.com
6
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相关代理商/技术参数 |
参数描述 |
|---|---|
| A6281KIT | 制造商:Allegro MicroSystems 功能描述:EVALIATION KIT |
| A6282 | 制造商:ALLEGRO 制造商全称:Allegro MicroSystems 功能描述:16-Channel Constant-Current LED Driver |
| A6282AEESTR-T | 制造商:Allegro MicroSystems LLC 功能描述: |
| A6282AELPTR-T | 制造商:Allegro MicroSystems LLC 功能描述: |
| A6282EES-T | 制造商:Allegro MicroSystems 功能描述:LED DRIVER 16 CH CONST-CURRENT 制造商:Allegro MicroSystems 功能描述:LED DRIVER, 16 CH, CONST-CURRENT 制造商:Allegro MicroSystems 功能描述:LED DRIVER, 16 CH, CONST-CURRENT; Topology:Constant Current; No. of Outputs:16; Output Current:51.1mA; Output Voltage:12V; Driver Case Style:QFN; Input Voltage Min:3V; Input Voltage Max:5.5V; Switching Frequency:30MHz; Operating ;RoHS Compliant: Yes |
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