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LPC11CX2_CX4 All information provided in this document is subject to legal disclaimers. © NXP B.V. 2013. All rights reserved.
Product data sheet Rev. 3.1 — 15 May 2013 47 of 62
NXP Semiconductors
LPC11Cx2/Cx4
32-bit ARM Cortex-M0 microcontroller
[6] The maximum t
f
for the SDA and SCL bus lines is specified at 300 ns. The maximum fall time for the SDA
output stage t
f
is specified at 250 ns. This allows series protection resistors to be connected in between the
SDA and the SCL pins and the SDA/SCL bus lines without exceeding the maximum specified t
f
.
[7] In Fast-mode Plus, fall time is specified the same for both output stage and bus timing. If series resistors
are used, designers should allow for this when considering bus timing.
[8] The maximum t
HD;DAT
could be 3.45 s and 0.9 s for Standard-mode and Fast-mode but must be less than
the maximum of t
VD;DAT
or t
VD;ACK
by a transition time (see UM10204). This maximum must only be met if
the device does not stretch the LOW period (t
LOW
) of the SCL signal. If the clock stretches the SCL, the
data must be valid by the set-up time before it releases the clock.
[9] tSU;DAT is the data set-up time that is measured with respect to the rising edge of SCL; applies to data in
transmission and the acknowledge.
[10] A Fast-mode I
2
C-bus device can be used in a Standard-mode I
2
C-bus system but the requirement t
SU;DAT
=
250 ns must then be met. This will automatically be the case if the device does not stretch the LOW period
of the SCL signal. If such a device does stretch the LOW period of the SCL signal, it must output the next
data bit to the SDA line t
r(max)
+ t
SU;DAT
= 1000 + 250 = 1250 ns (according to the Standard-mode I
2
C-bus
specification) before the SCL line is released. Also the acknowledge timing must meet this set-up time.
10.6 SPI interfaces
Fig 20. I
2
C-bus pins clock timing
002aaf425
t
f
70 %
30 %
SDA
t
f
70 %
30 %
S
70 %
30 %
70 %
30 %
t
HD;DAT
SCL
1 / f
SCL
70 %
30 %
70 %
30 %
t
VD;DAT
t
HIGH
t
LOW
t
SU;DAT
Table 18. Dynamic characteristics of SPI pins in SPI mode
Symbol Parameter Conditions Min Typ Max Unit
SPI master (in SPI mode)
T
cy(clk)
clock cycle time full-duplex mode
[1]
50 - - ns
when only transmitting
[1]
40 ns
t
DS
data set-up time in SPI mode
2.4 V V
DD
3.6 V
[2]
15 - - ns
2.0 V V
DD
< 2.4 V
[2]
20 ns
1.8 V V
DD
< 2.0 V
[2]
24 - - ns
t
DH
data hold time in SPI mode
[2]
0-- ns
t
v(Q)
data output valid time in SPI mode
[2]
--10 ns
t
h(Q)
data output hold time in SPI mode
[2]
0-- ns
SPI slave (in SPI mode)
T
cy(PCLK)
PCLK cycle time 20 - - ns