PCA9538A 查看數據表（PDF） - NXP Semiconductors.

零件编号

产品描述 (功能)

生产厂家

PCA9538A

Low-voltage 8-bit I2C-bus I/O port with interrupt and reset

NXP Semiconductors. 

NXP Semiconductors

PCA9538A

Low-voltage 8-bit I2C-bus I/O port with interrupt and reset

8.1 Minimizing IDD when the I/Os are 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 VI is about 1.2 V less than VDD. The supply current, IDD, increases as VI becomes

lower than VDD.

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 VI

at or above VDD and prevents additional supply current consumption when the LED is off.

VDD

3.3 V

5V

VDD

Pn

LED

100 kΩ

VDD

LED

Pn

002aag164

Fig 12. High value resistor in parallel with

the LED

002aag165

Fig 13. Device supplied by a lower voltage

8.2 12 V tolerant I/Os

The PCA9538A device SCR group reference diode can go up to 10 V before latch back to

8 V. The ESD gate oxide will protect the device, but not if used continually. Therefore, to

achieve 12 V tolerant I/Os, the external protection circuitry (diode) must be used as shown

in Figure 14.

A0

VDD

A1

SDA

RESET

SCL

P0

INT

PCA9538A

P1

P7

P2

P6

P3

P5

VSS

P4

+5 V +12 V

Fig 14. External protection circuitry

002aah421

PCA9538A

Product data sheet

All information provided in this document is subject to legal disclaimers.

Rev. 1 — 28 September 2012

© NXP B.V. 2012. All rights reserved.

12 of 37

Share Link: