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| 型号： | A8502KLPTR-T |
| 厂商： | Allegro Microsystems Inc |
| 文件页数： | 11/35页 |
| 文件大小： | 0K |
| 描述： | IC LED DVR WHITE MULTI 16-TSSOP |
| 标准包装： | 8,000 |
| 拓扑： | PWM，升压（升压） |
| 输出数： | 2 |
| 内部驱动器： | 是 |
| 类型 - 主要： | 车载，背光 |
| 类型 - 次要： | 白色 LED |
| 频率： | 580kHz ~ 2MHz |
| 电源电压： | 5 V ~ 40 V |
| 安装类型： | 表面贴装 |
| 封装/外壳： | 16-TSSOP（0.173"，4.40mm）裸露焊盘 |
| 供应商设备封装： | 16-TSSOP-EP |
| 包装： | 带卷 (TR) |
| 工作温度： | -40°C ~ 125°C |
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A8502
Wide Input Voltage Range, High Efficiency
Fault Tolerant LED Driver
Functional Description
The A8502 incorporates a current-mode boost controller with
internal DMOS switch, and two LED current sinks. It can be
used to drive two LED strings of up to 12 white LEDs in series,
with current up to 120 mA per string. For optimal efficiency, the
output of the boost stage is adaptively adjusted to the minimum
voltage required to power both LED strings. This is expressed by
C1
VDD
FSET/SYNC
the following equation:
V OUT = max ( V LED1 , V LED2 ) + V REG
where
(1)
C2
C3
ISET
V LEDx is the voltage drop across LED strings 1 and 2, and
V REG is the regulation voltage of the LED current sinks (typi-
cally 0.72 V at the maximum LED current).
Enabling the IC
The IC turns on when a logic high signal is applied on the
PWM/EN pin with a minimum duration of t PWMH for the first
clock cycle, and the input voltage present on the VIN pin is
greater than the 4.35 V necessary to clear the UVLO (V UVLOrise )
threshold. The power-up sequence is shown in figure 2. Before
the LEDs are enabled, the A8502 driver goes through a system
check to determine if there are any possible fault conditions that
might prevent the system from functioning correctly. Also, if the
FSET/SYNC pin is pulled low, the IC will not power-up. More
information on the FSET/SYNC pin can be found in the Sync
section of this datasheet.
PWM/EN
C4
t
Figure 2. Power-up diagram; shows VDD (ch1, 2 V/div.), FSET/SYNC (ch2,
1 V/div.), ISET (ch3, 1 V/div.), and PWM/EN (ch4, 2 V/div.) pins,
time = 200 μ s/div.
GATE = V IN – 4.5 V
GATE
C1
LEDx
Powering up: LED pin short-to-ground check
The VIN pin has a UVLO function that prevents the A8502
from powering-up until the UVLO threshold is reached. After
the VIN pin goes above UVLO, and a high signal is present on
C2
C3
ISET
LED detection period
the PWM/EN pin, the IC proceeds to power-up. As shown in
figure 3, at this point the A8502 enables the disconnect switch
and checks if any LEDx pins are shorted to ground and/or are not
C4
PWM/EN
used.
The LED detect phase starts when the GATE voltage of the
disconnect switch is equal to V IN – 4.5 V. After the voltage
threshold on the LEDx pins exceeds 120 mV, a delay of between
3000 and 4000 clock cycles is used to determine the status of the
pins. Thus, the LED detection duration varies with the switching
t
Figure 3. Power-up diagram; shows the relationship of an LEDx pin with
respect to the gate voltage of the disconnect switch (if used) during the
LED detect phase, as well as the duration of the LED detect phase for a
switching frequency of 2 MHz; shows GATE (ch1, 5 V/div.), LED (ch2,
500 mV/div.), ISET (ch3, 1 V/div.), and PWM/EN (ch4, 5 V/div.) pins,
time = 500 μ s/div.
Allegro MicroSystems, LLC
115 Northeast Cutoff
Worcester, Massachusetts 01615-0036 U.S.A.
1.508.853.5000; www.allegromicro.com
11
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| A8503 | 制造商:ALLEGRO 制造商全称:Allegro MicroSystems 功能描述:High Efficiency 6-Channel, 2 MHz, WLED/RGB Driver |
| A8503EECTR-T | 功能描述:IC LED DRVR WHT/RGB BCKLGT 26QFN RoHS:是 类别:集成电路 (IC) >> PMIC - LED 驱动器 系列:- 标准包装:1 系列:- 恒定电流:- 恒定电压:- 拓扑:PWM，切换式电容器（充电泵） 输出数:1 内部驱动器:是 类型 - 主要:背光 类型 - 次要:白色 LED 频率:642kHz 电源电压:2.7 V ~ 5.5 V 输出电压:5V 安装类型:表面贴装 封装/外壳:10-VFDFN 裸露焊盘 供应商设备封装:10-VSON 包装:剪切带 (CT) 工作温度:-30°C ~ 85°C 产品目录页面:1371 (CN2011-ZH PDF) 其它名称:BD1603NUV-E2CT |
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| A8504 | 制造商:ALLEGRO 制造商全称:Allegro MicroSystems 功能描述:WLED/RGB Backlight Driver for Medium Size LCDs |
| A8504910100N | 功能描述:环形MIL规格后盖 Backshell, Envrn, EMI/RFI, Strt, Nickel, Size 48 RoHS:否 制造商:Amphenol PCD MIL 类型:MIL-DTL-38999 III, IV 系列:AS85049 产品类型:Environmental EMI/RFI Backshells 外壳类型:Straight 外壳大小:18 外壳材质:Aluminum Alloy |
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