PCA9549 데이터 시트보기 (PDF) - Philips Electronics
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PCA9549 Datasheet PDF : 24 Pages
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Philips Semiconductors
PCA9549
Octal bus switch with individually I2C-bus controlled enables
5.0
Vo(sw)
(V)
4.0
3.0
2.0
002aaa964
(1)
(2)
(3)
1.0
2.0 2.5 3.0 3.5 4.0 4.5 5.0 5.5
VDD (V)
(1) maximum
(2) typical
(3) minimum
Fig 7. Vo(sw) voltage versus VDD
Figure 7 shows the voltage characteristics of the pass gate transistors (note that the
PCA9549 is only tested at the points specified in Section 9 “Static characteristics”). In
order for the PCA9549 to act as a voltage translator, the Vo(sw) voltage should be equal to,
or lower than the lowest bus voltage. For example, if the main bus was running at 5 V, and
the downstream buses were 3.3 V and 2.7 V, then Vo(sw) should be equal to or below 2.7 V
to effectively clamp the downstream bus voltages. Looking at Figure 7, we see that Vo(sw)
(maximum) will be at 2.7 V when the PCA9549 supply voltage is 3.5 V or lower so the
PCA9549 supply voltage could be set to 3.3 V. Pull-up resistors can then be used to bring
the bus voltages to their appropriate levels (see Figure 16).
PCA9549_1
Product data sheet
Rev. 01 — 11 July 2006
© Koninklijke Philips Electronics N.V. 2006. All rights reserved.
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