PCA9539 查看數據表（PDF） - Philips Electronics
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PCA9539 Datasheet PDF : 21 Pages
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Philips Semiconductors
16-bit I2C and SMBus, low power I/O port with interrupt
Product data sheet
PCA9539
TYPICAL APPLICATION
VDD
(5 V)
VDD
10 kΩ 10 kΩ 10 kΩ 10 kΩ
SCL
MASTER
CONTROLLER
SDA
INT
RESET
GND
VDD
SCL
SDA
INT
RESET
2 kΩ
I/O0.0
I/O0.1
I/O0.2
I/O0.3
I/O0.4
I/O0.5
PCA9539
I/O0.6
I/O0.7
I/O1.0
I/O1.1
A1
I/O1.2
I/O1.3
A0
I/O1.4
I/O1.5
I/O1.6
VSS I/O1.7
100 kΩ
(×3)
SUBSYSTEM 1
(e.g. temp sensor)
INT
SUBSYSTEM 2
(e.g. counter)
RESET
A
ALARM
SUBSYSTEM 3
(e.g. alarm system)
ENABLE
B
VDD
Controlled Switch
(e.g. CBT device)
10 DIGIT
NUMERIC
KEYPAD
NOTE: Device address configured as 1110100 for this example
I/O0.0, I/O0.2, I/O0.3, configured as outputs
I/O0.1, I/O0.4, I/O0.5, configured as inputs
I/O0.6, I/O0.7, and I/O1.0 to I/O1.7 configured as inputs
Figure 11. Typical application
SW02094
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 11. 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 12 shows a high value resistor in parallel with the LED. Figure 13 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 12. High value resistor in parallel with the LED
2004 Sep 30
11
VDD
LEDx
LED
SW02087
Figure 13. Device supplied by a lower voltage
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