pcf85132 NXP Semiconductors, pcf85132 Datasheet - Page 37
pcf85132
Manufacturer Part Number
pcf85132
Description
Pcf85132 Lcd Driver For Low Multiplex Rates
Manufacturer
NXP Semiconductors
Datasheet
1.PCF85132.pdf
(54 pages)
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NXP Semiconductors
12. Application information
PCF85132
Product data sheet
12.1.1 Max value of pull-up resistor
12.1.2 Min value of pull-up resistor
12.1 Pull-up resistor sizing on I
The bus capacitance (C
capacitance on pin SDA limits the maximum value of the pull-up resistor (R
specified rise time.
According to the I
input threshold of V
t
whereas t1 and t2 are the time since the charging started. The values for t1 and t2 are
derivatives of the functions V(t1) and V(t2):
with the results of
R
calculated with
The supply voltage limits the minimum value of resistor R
sink current (see value of I
calculated with
The designer now has the minimum and maximum value of R
and R
V t1
V t2
R
R
r
t2
t
t
t1
r
PU(max)
( )
( )
PU max
PU min
will be calculated with
r
=
=
=
=
(
(
–
t2 t1
PU(min)
–
–
=
=
R
R
R
)
)
–
PU
0.3V
0.7V
PU
is a function of the rise time (t
PU
=
=
C
C
C
V
------------------------- -
---------------------- -
0.8473C
b
are shown in
b
b
DD
DD
DD
×
×
×
Equation
Equation
I
All information provided in this document is subject to legal disclaimers.
ln 0.3
t
OL
ln 0.3
ln 0.7
–
r
=
=
2
(
(
(
V
C-bus specification the rise time (t
IL
V
V
OL
b
DD
DD
)
=
= 0.3V
Rev. 1 — 23 November 2010
)
)
+
(
(
300
------------------------- -
b
Equation
0.8473C
R
1 e
1 e
) is the total capacitance of wire, connections, and pins. This
14:
15:
PU
OL
–
–
Figure 26
×
DD
C
-t1 R
-t2 R
on pin SDAACK in
10
b
and V
×
⁄
⁄
9 –
b
ln 0.7
PU
PU
8:
2
(
C-bus
C
C
b
b
and
IH
)
)
)
r
) and the bus capacitance (C
= 0.7V
Figure
DD
27.
Table
. The value for t
r
) is defined between the V
LCD driver for low multiplex rates
18). R
PU
due to the specified minimum
PU(min)
PU
. The values for R
r(max)
as a function of V
PCF85132
b
) and will be
is 300 ns.
© NXP B.V. 2010. All rights reserved.
PU
) due to the
DD
PU(max)
related
37 of 54
DD
(10)
(12)
(13)
(14)
(15)
(11)
(8)
(9)
is