pca9646 NXP Semiconductors, pca9646 Datasheet - Page 13

• Manufacturer Part Number: pca9646
• Description: Pca9646 Buffered 4-channel 2-wire Bus Switch
• Manufacturer: NXP Semiconductors

NXP Semiconductors
PCA9646
Product data sheet
Fig 17. PCA9646 series implementation for large I/O fan-out
U1
MASTER
BUS
V
DD
SDA
SCL
SCL
dashed box
structure in
repeated
etc.
R1
180 Ω
The PCA9646 may also be driven in series.
scenario, each of the four outputs of the first device (U2) has six more PCA9646’s
connected to it. Each of those six devices has four outputs, thus giving
4  7  4 = 112 outputs. If the RESET pin on U2 was also driven from the master, it would
be possible to reproduce this entire structure multiple times, giving a truly massive
address space capability. Such a configuration may be applied to situations such as
display drivers.
000b
R2
180 Ω
3
U2
SCL
SDA
RESET
A[2:0]
PCA9646
V
All information provided in this document is subject to legal disclaimers.
DD
(address: 001b to 111b)
up to seven PCA9646s
on each output pair
SC0
SC1
SC2
SC3
SD0
SD1
SD2
SD3
Rev. 1 — 1 March 2011
180 Ω
R3
001b
010b
R4
180 Ω
3
3
Figure 17
(address: 001b to 111b)
up to seven devices
U3
U4
SCL
SDA
RESET
A[2:0]
SCL
SDA
RESET
A[2:0]
PCA9646
PCA9646
Buffered 4-channel 2-wire bus switch
V
V
5 V
5 V
DD
DD
shows this configuration. In this
SC0
SC1
SC2
SC3
SD0
SD1
SD2
SD3
SC0
SC1
SC2
SC3
SD0
SD1
SD2
SD3
connect, for example,
8 LED driver ICs,
each with 8 LED
outputs = 7168 LEDs
total output of
4 × 7 × 4 = 112
individually enabled
fully isolated buses,
each with full
capacitance load
(e.g., 400 pF at 1 MHz)
PCA9646
© NXP B.V. 2011. All rights reserved.
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