74HC161 Datasheet – Synchronous 4-bit Binary Counter ( PDF )

Part Number: 74HC161

Function: Presettable synchronous 4-bit binary counter, asynchronous reset

Package: DIP, SOP 16 Pin Type

Manufacturer: Philips Electronics ( https://www.nxp.com/ )


74HC161 datasheet



The 74HC161 / 74HCT161 are high-speed Si-gate CMOS devices and are pin compatible with low power Schottky TTL (LSTTL). They are specified in compliance with JEDEC standard no. 7A.

The devices are synchronous presettable binary counters which feature an internal look-ahead carry and can be used for high-speed counting. Synchronous operation is provided by having all flip-flops clocked simultaneously on the positive-going edge of the clock (CP).


1. Synchronous counting and loading

2. Two count enable inputs for n-bit cascading

3. Positive-edge triggered clock

4. Asynchronous reset

5. Output capability : standard

6. ICC category : MSI

Other data sheets are available within the file:

74161, 74HC161D, 74HC161DB, 74HC161NB


74HC161 Datasheet PDF Download

74HC161 pdf

PCA9557PW Datasheet – 8-bit I2C-bus and SMBus I/O port

Part Number: PCA9557PW

Function: 8-bit I2C-bus and SMBus I/O port with reset

Package: SO 16, TSSOP 16, HVQFN16 Type

Manufacturer: NXP Semiconductors.


PCA9557PW datasheet


The PCA9557 is a silicon CMOS circuit which provides parallel input/output expansion for
SMBus and I2C-bus applications. The PCA9557 consists of an 8-bit input port register,
8-bit output port register, and an I2C-bus/SMBus interface. It has low current consumption
and a high-impedance open-drain output pin, IO0.

The system master can enable the PCA9557’s I/O as either input or output by writing to
the configuration register. The system master can also invert the PCA9557 inputs by
writing to the active HIGH polarity inversion register. Finally, the system master can reset
the PCA9557 in the event of a time-out by asserting a LOW in the reset input.



1. Lower voltage, higher performance migration path for the PCA9556

2. 8 general purpose input/output expander/collector

3. Input/output configuration register

4. Active HIGH polarity inversion register

5. I2C-bus and SMBus interface logic

6. Internal power-on reset

7. Noise filter on SCL/SDA inputs

8. Active LOW reset input


PCA9557PW Datasheet PDF Download

PCA9557PW pdf

Other data sheets are available within the file: 9557, PCA9557, PCA9557BS, PCA9557D, PCA9557-PW