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Número de pieza | PCF8883 | |
Descripción | Capacitive proximity switch | |
Fabricantes | NXP Semiconductors | |
Logotipo | ||
Hay una vista previa y un enlace de descarga de PCF8883 (archivo pdf) en la parte inferior de esta página. Total 24 Páginas | ||
No Preview Available ! PCF8883
www.DataSheet4U.com
Capacitive proximity switch with auto-calibration, large
voltage operating range and very low power consumption
Rev. 01 — 16 October 2009
Product data sheet
1. General description
The integrated circuit PCF8883 is a capacitive proximity switch that uses a patented
(EDISEN) digital method to detect a change in capacitance on a remote sensing plate.
Changes in the static capacitance (as opposed to dynamic capacitance changes) are
automatically compensated using continuous auto-calibration. Remote sensing plates
(e.g. conductive foil) can be connected directly to the IC1 or remotely using a coaxial
cable.
2. Features
I Dynamic proximity switch
I Digital processing method
I Adjustable sensitivity, can be made very high
I Adjustable response time
I Wide input capacitance range (10 pF to 60 pF)
I Automatic calibration
I A large distance (several meters) between the sensing plate and the IC is possible
I Open-drain output (P-type MOSFET, external load between pin and ground)
I Designed for battery powered applications (IDD = 3 µA, typical)
I Output configurable as push-button, toggle, or pulse
I Wide voltage operating range (VDD = 3 V to 9 V)
I Large temperature operating range (Tamb = −40 °C to +85 °C)
I Internal voltage regulator
I Available in SOIC8 (other packages available on request for larger quantities)
1. The definition of the abbreviations and acronyms used in this data sheet can be found in Section 16.
1 page NXP Semiconductors
PCF8883www.DataSheet4U.com
Capacitive proximity switch with auto-calibration
8. Functional description
Figure 3 and Figure 4 show the functional principle of the PCF8883. The discharge time
(tdch) of a chip-internal RC timing circuit, to which the external sensing plate is connected
via pin IN, is compared to the discharge time (tdch(ref)) of a second chip-internal reference
RC timing circuit. Both RC timing circuits are periodically charged from VDD(INTREGD) via
identical switches and then discharged via a resistor to ground (VSS). Both switches are
synchronized.
VDD(INTREGD)
Vref
fs
VDD(INTREGD)
&
CUP
CDN
&
IN
COUNTER
LOGIC
Isink
VSS CPC
013aaa093
Fig 3. Functional diagram of the sensor logic
The charge-discharge cycle is governed by the sampling rate (fs). If the voltage of one of
the RC timing circuits falls below the internal reference voltage Vref, the respective
comparator output will become LOW. The logic following the comparators determines
which comparator switches first. If the upper (reference) comparator switches then a pulse
is given on CUP. If the lower (input) comparator switches first then a pulse is given on
CDN (see Figure 3).
The pulses control the charge on the external capacitor CCPC on pin CPC. Every time a
pulse is given on CUP, capacitor CCPC is charged from VDD(INTREGD) for a fixed time
causing the voltage on CCPC to rise. Likewise when a pulse occurs on CDN, capacitor
CCPC is connected to a current sink to ground for a fixed time causing the voltage on CCPC
to fall.
PCF8883_1
Product data sheet
Rev. 01 — 16 October 2009
© NXP B.V. 2009. All rights reserved.
5 of 24
5 Page NXP Semiconductors
PCF8883www.DataSheet4U.com
Capacitive proximity switch with auto-calibration
11. Dynamic characteristics
Table 6. Dynamic characteristics
VDD = 5 V, CCLIN = 22 pF, CCPC = 470 nF, Tamb = +25 °C; unless otherwise specified.
Symbol Parameter
Conditions
CCLIN
CCPC
Nres(dig)eq
CTYPE
Ci
capacitance on pin CLIN
capacitance on pin CPC
equivalent digital resolution
capacitance on pin TYPE
input capacitance
RDSon
tch
tdch
tstartup
tp
fs
drain-source on-state resistance
charge time
discharge time
start-up time
pulse duration
sampling frequency
tsw switching time
X7R ceramic chip capacitor
sensing plate and connecting cable
sensing plate and connecting cable;
Tamb = −40 °C to +85 °C;
VDD = 3.0 V
internal pull-up on input
per sample
per sample
until normal operation is established
on pin OUT; in pulse mode;
CTYPE ≥ 10 nF
CCLIN = 0 pF
CCLIN = 22 pF (typical value)
CCLIN = 100 pF
at fs = 1 kHz
Min Typ Max Unit
0 22 100 pF
90 470 2500 nF
- 14 - bit
0.1 -
470 nF
10 -
60 pF
10 -
40 pF
- - 500 Ω
1.4 2.5 3.5 µs
- 1.0 - µs
- 0.5 - s
- 2.5 - ms/nF
- 3.3 - kHz
- 1 - kHz
- 275 - Hz
- 64 - ms
PCF8883_1
Product data sheet
Rev. 01 — 16 October 2009
© NXP B.V. 2009. All rights reserved.
11 of 24
11 Page |
Páginas | Total 24 Páginas | |
PDF Descargar | [ Datasheet PCF8883.PDF ] |
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