PCA9553D02 查看數據表（PDF） - Philips Electronics
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PCA9553D02 Datasheet PDF : 18 Pages
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Philips Semiconductors
4-bit I2C LED driver with programmable blink rates
Product data sheet
PCA9553
APPLICATION DATA
5V
5V
SDA
SCL
I2C/SMBus MASTER
10 kΩ 10 kΩ
SDA
SCL
VDD
LED0
LED1
LED2
LED3
VSS
PCA9553
Figure 13. Typical application
SW01039
Minimizing IDD when the I/O is used to control LEDs
When the I/Os are used to control LEDs, they are normally connected to VDD through a resistor as shown in Figure 13. Since the LED acts as a
diode, when the LED is off the I/O VIN is about 1.2 V less than VDD. The supply current, IDD, increases as VIN becomes lower than VDD and is
specified as ∆IDD in the DC characteristics table.
Designs needing to minimize current consumption, such as battery power applications, should consider maintaining the I/O pins greater than or
equal to VDD when the LED is off. Figure 14 shows a high value resistor in parallel with the LED. Figure 15 shows VDD less than the LED supply
voltage by at least 1.2 V. Both of these methods maintain the I/O VIN at or above VDD and prevents additional supply current consumption when
the LED is off.
VDD
3.3 V
5V
VDD
LEDx
LED
100 kΩ
SW02086
Figure 14. High value resistor in parallel with the LED
VDD
LEDx
LED
SW02087
Figure 15. Device supplied by a lower voltage
2004 Oct 01
9
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