PCA9509D(2009) Просмотр технического описания (PDF) - NXP Semiconductors.
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PCA9509D Datasheet PDF : 19 Pages
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NXP Semiconductors
PCA9509
Level translating I2C-bus/SMBus repeater
[2] If the PCA9509 is not being enabled or disabled, the VCC(A) minimum is 0.95 V with a corresponding decrease in the IIL, which will drop
below the minimum specification of −450 µA at cold temperature (see Figure 8 and Figure 9). This will not significantly change the rise
and fall times of the signals on port A since the IIL value represents the current source pull-up current, so a lower current into the same
capacitance will result in a slower rise time and a longer transition time in general, however since the lower current is also associated
with a lower voltage swing the delay is somewhat compensated. The key point of the graphs is that the current has a temperature
dependence, and the output driver will also have the same temperature dependency so that the output offset of ~200 mV on port A is
nearly temperature independent. Even though the IIL parameter indicates that at VCC(A) of 0.95 V the PCA9509 can only sink up to
400 µA instead of 450 µA at cold temperature, the output is designed to be somewhat resistive such that under nominal conditions
(1.1 V) the current source pull-up will source 1 mA and the output pull-down will sink the 1 mA at ~200 mV, so as the current source
current decreases the output pull-down resistance increases in order to maintain the offset.
[3] VIL specification is for the falling edge seen by the port A input. VILc is for the static LOW levels seen by the port A input resulting in
port B output staying LOW.
[4] The port A current source has a typical value of about 1 mA, but varies with both VCC(A) and VCC(B). Below VCC(A) of about 0.7 V the
port A current source current drops to 0 mA. The current source current dropping across the internal pull-down driver resistance of
about 200 Ω defines the VOL.
[5] As long as the chip ground is common with the input ground reference the driver resistance may be as large as 120 Ω. However, ground
offset will rapidly decrease the maximum allowed driver resistance.
[6] Guaranteed by design.
0
IIL
(mA)
−0.4 (1)
−0.8
(2)
(3)
(4)
002aae733
−1.2
(5)
−1.6
−40
25
85
Tamb (°C)
Pins under test = An pins
(1) High limit
(2) Maximum
(3) Mean
(4) Minimum
(5) Low limit
Fig 8. LOW-level input current as a function of
temperature; VCC(A) = 1.0 V
0
IIL
(mA)
−0.4
−0.8
002aae734
(2)
(1)
(3)
(4)
−1.2
−1.6
−40
(5)
25
85
Tamb (°C)
Pins under test = An pins
(1) High limit
(2) Maximum
(3) Mean
(4) Minimum
(5) Low limit
Fig 9. LOW-level input current as a function of
temperature; VCC(A) = 0.95 V
PCA9509_5
Product data sheet
Rev. 05 — 10 July 2009
© NXP B.V. 2009. All rights reserved.
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