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参数资料
| 型号： | SP7122BEB |
| 厂商： | Exar Corporation |
| 文件页数： | 4/18页 |
| 文件大小： | 0K |
| 描述： | EVAL BOARD FOR SP7122B |
| 标准包装： | 1 |
| 电流 - 输出 / 通道： | 15mA |
| 输出及类型： | 2，非隔离 |
| 特点： | PWM 亮度控制 |
| 输入电压： | 2.7 ~ 5.5 V |
| 已供物品： | 板 |
| 已用 IC / 零件： | SP7120A |
OUTPUT CURRENT SELECTION TABLE
Part Number
SP7120A
SP7120B
SP7120C
SP7122A
SP7122B
SP7122C
Output
Current per
channel
15mA
20mA
25mA
15mA
20mA
25mA
Number
of
Channels
2
2
2
3
3
3
Comments
Channels can be combined for higher output current
Channels can be combined for higher output current
Channels can be combined for higher output current
Channels can be combined for higher output current
Channels can be combined for higher output current
Channels can be combined for higher output current
CIRCUIT DESCRIPTION
The SP712X drivers are regulated current
sources with an enable input. The SP7120
and SP7122 have factory preset LED
current at three programmed levels: 15mA,
20mA or 25mA (versions A, B, and C
respectively). The SP712X circuit consists
of enable, bandgap reference, and current
amplifier circuit blocks. Enable circuit block
provides the enable and PWM function for
the SP712x. The bandgap reference
provides a stable voltage source from which
the output current is derived.
ENABLE
The SP712X drivers have a low current
shutdown function. In shutdown mode, the
part draws less than 1 μ A current maximum.
The part can be set into shutdown mode
using the EN pin (EN = LOW). The enable
pin cannot be left floating. There are no
predefined internal states, so leaving this
pin open will cause the part to operate
incorrectly.
PWM Dimming
The SP712X drivers allow LED-dimming
control by applying PWM signaling to EN
pin. The acceptable frequency range of this
signal is 100Hz to 20 kHz. The minimum
ON time that is required for the Enable pin
is 15 μ s. Thus for a 2kHz PWM signal, the
acceptable duty cycle range is 3% to 100%.
To find the minimum PWM duty cycle the
following steps are needed:
Step 1: Determine the time period of the
PWM frequency
?
Where PWM f is the PWM frequency
Step 2: take the minimum enable ON time;
this is 15 μ S for the SP712x parts
Example
For a 2kHz signal the minimum duty
cycle for the PWM signal is
%Minimum Duty cycle = 3%
Fault Operation
If one of LEDs is shorted, the voltage across
The Sp712X for that LED pin will be Vcc,
but that channel will still provide the nominal
current value thus increasing power
dissipation. If all channels are shorted,
excessive power dissipation may damage
the device. If an LED is open, the LED pin
voltage will be pulled up to Vcc, and LED
Jan 7 ‘08 RevE
SP7120/22 Low Dropout LED Driver
page 4
? 2007 Sipex Corporation
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相关代理商/技术参数 |
参数描述 |
|---|---|
| SP7122BEK-L | 功能描述:LED照明驱动器 Common Cathode Linear LED Driver RoHS:否 制造商:STMicroelectronics 输入电压:11.5 V to 23 V 工作频率: 最大电源电流:1.7 mA 输出电流: 最大工作温度: 安装风格:SMD/SMT 封装 / 箱体:SO-16N |
| SP7122BEK-L/TR | 功能描述:LED照明驱动器 COMMON CATHODE RoHS:否 制造商:STMicroelectronics 输入电压:11.5 V to 23 V 工作频率: 最大电源电流:1.7 mA 输出电流: 最大工作温度: 安装风格:SMD/SMT 封装 / 箱体:SO-16N |
| SP7122CEB | 功能描述:LED照明驱动器 Common Cathode Linear LED Driver RoHS:否 制造商:STMicroelectronics 输入电压:11.5 V to 23 V 工作频率: 最大电源电流:1.7 mA 输出电流: 最大工作温度: 安装风格:SMD/SMT 封装 / 箱体:SO-16N |
| SP7122CEK-L/TR | 制造商:SIPEX 制造商全称:Sipex Corporation 功能描述:2 or 3 Channel Low Dropout High Side Linear LED Driver |
| SP7125 | 制造商:SIPAT 制造商全称:SIPAT 功能描述:SAW Filter Electrical Characteristic |
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