NXP Semiconductors
PCA9551
8-bit I 2 C-bus LED driver with programmable blink rates
8. Application design-in information
5V
5V
I 2 C-BUS/SMBus
MASTER
10 k ?
10 k ?
10 k ?
V DD
PCA9551
SDA
SCL
SDA
SCL
RESET
LED0
LED1
LED2
LED3
LED4
LED5
A2
LED6
LED7
GPIOs
A1
A0
V SS
002aac510
LED0 to LED5 are used as LED drivers.
LED6 and LED7 are used as regular GPIOs.
Fig 14. Typical application
8.1 Minimizing I DD when the I/Os are used to control LEDs
When the I/Os are used to control LEDs, they are normally connected to V DD through a
resistor as shown in Figure 14 . Since the LED acts as a diode, when the LED is off the
I/O V I is about 1.2 V less than V DD . The supply current, I DD , increases as V I becomes
lower than V DD and is speci?ed as ? I DD in Table 12 “Static characteristics” .
Designs needing to minimize current consumption, such as battery power applications,
should consider maintaining the I/O pins greater than or equal to V DD when the LED is off.
Figure 15 shows a high value resistor in parallel with the LED. Figure 16 shows V DD less
than the LED supply voltage by at least 1.2 V. Both of these methods maintain the I/O V I
at or above V DD and prevents additional supply current consumption when the LED is off.
V DD
3.3 V
5V
V DD
LED
100 k ?
V DD
LED
PCA9551_8
LEDn
002aac189
Fig 15. High value resistor in parallel with
the LED
LEDn
002aac190
Fig 16. Device supplied by a lower voltage
? NXP B.V. 2008. All rights reserved.
Product data sheet
Rev. 08 — 31 July 2008
11 of 26
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相关代理商/技术参数
PCA9551BS118 制造商:Rochester Electronics LLC 功能描述: 制造商:NXP 功能描述: 制造商:NXP Semiconductors 功能描述:
PCA9551BSHP 功能描述:LED照明驱动器 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
PCA9551BS-T 功能描述:LED照明驱动器 8-BIT I2C FM OD LED BLK RST 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
PCA9551D 制造商:PHILIPS 制造商全称:NXP Semiconductors 功能描述:8-bit I2C LED driver with programmable blink rates
PCA9551D,112 功能描述:LED照明驱动器 I2C LED BLINKER 8BIT 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
PCA9551D,118 功能描述:LED照明驱动器 8-BIT I2C FM OD LED BLK RST 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
PCA9551D-T 制造商:PHILIPS 制造商全称:NXP Semiconductors 功能描述:8-bit I2C-bus LED driver with programmable blink rates
PCA9551PW 功能描述:LED照明驱动器 I2C LED BLINKER 8BIT 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