|
|
PDF PCA9901 Data sheet ( Hoja de datos )
| Número de pieza | PCA9901 | |
| Descripción | One Wire Single LED Driver | |
| Fabricantes | NXP Semiconductors | |
| Logotipo |  |
|
Hay una vista previa y un enlace de descarga de PCA9901 (archivo pdf) en la parte inferior de esta página. Total 27 Páginas | ||
|
No Preview Available !
PCA9901
One wire single LED driver
Rev. 01 — 3 December 2009
Product data sheet
1. General description
The PCA9901 is a 20 mA current source for a single LED that allows stand-alone blinking
of a predefined pattern to off-load the microcontroller and save battery power.
Programming of the device is done through a training sequence: the host controller sends
the LED lighting sequence and the PCA9901 memorizes it. Once the sequence has been
memorized, the PCA9901 can be programmed to send it once or in a loop until the host
controller requests the sequence to be stopped.
Commands and blinking sequence are sent through a uni-directional one-wire interface.
Commands include: Training Start, Training End, Execute Sequence (once or in loop until
a Stop Command is requested) and Reset. A blinking sequence includes up to 3 different
blinking patterns, each defined by its ON and OFF timings.
A bypass mode allows the training sequence to be ignored and the LED output to follow
the one-wire interface Logic state to directly control the LED from the microcontroller.
An external resistor sets the maximum current that flows in the LED, which can be set
between 1 mA and 20 mA.
The PCA9901 operates from a 2.7 V to 5.5 V power supply.
2. Features
www.DataSheet4U.com
1 wire interface to control the device
Stand-alone blinking capability while training the sequence to blink
Sequence includes up to 3 blinking elements
12-bit (4096 steps) LED ON and OFF timings for each blinking element:
ON timing is captured between 1 ms and 255 ms
OFF timing is captured between 20 ms and 5.1 s
1.8 V compliant one-wire logic interface
Training Start, Training End, Run-Once, Run, Stop and Reset commands
High side current controlled LED driver with 1 mA to 20 mA max current in the LED set
by an external resistor. 5 mA drive capability when no external resistor is connected
110 mV max dropout voltage driver at 20 mA
Fully internal oscillator for sequence training, LED timing, Command and Sequencing
Controls
Short circuit and thermal protection
2.7 V to 5.5 V power supply
Very low quiescent current: < 0.75 μA
1 page  
NXP Semiconductors
PCA9901
One wire single LED driver
8. Functional description
Refer to Figure 2 “Block diagram of PCA9901”.
8.1 Digital interface overview - CTRL pin
The digital interface is a simple one-wire uni-directional interface allowing the host
controller device to:
• send the lighting sequence to the LEDOUT pin and request the PCA9901 to capture
and memorize it at the same time
• send the specific commands to execute the captured and memorized sequence later
• reset the PCA9901 to a known state at any time.
The lighting sequence to be captured by the PCA9901 contains the actual LED ON
(CTRL = 1) and LED OFF (CTRL = 0) timings. A sequence includes up to 3 different
patterns, each one containing one ON and one OFF value. Up to 3 LED ON and
3 LED OFF times can then be memorized by the PCA9901.
Commands are specific events that tell the PCA9901 what action needs to be performed.
The different commands are:
www.DataSheet4U.com
TRAINING START: Beginning of the training sequence. Upon reception of this
command, the PCA9901 starts capturing the lighting sequence.
TRAINING END: End of the training sequence. Upon reception of this command, the
capture stops, and the sequence is stored in the corresponding registers. The PCA9901
goes to Shutdown mode.
RUN ONCE: The sequence that has been memorized is executed once and then the
PCA9901 goes to Shutdown mode. If no sequence has been previously captured, the
PCA9901 goes to Shutdown mode.
RUN: The sequence that has been memorized is executed until a STOP Command
occurs.
STOP: The LED output is switched off at the end of the current LED ON time and the
PCA9901 goes to Shutdown mode.
RESET: The PCA9901 is reset and all the internal registers default to zeroes. The
PCA9901 goes to Shutdown mode.
The PCA9901 decodes the commands using a 1.5 ms window from the first LOW to HIGH
transition that occurs on the CTRL pin. The following command or the data following a
command must then be issued at least 1.5 ms after.
At the end of the 1.5 ms window:
• The PCA9901 is fully operational (in the case the command is issued while the
PCA9901 was in Shutdown mode)
• The command has been successfully decoded and the PCA9901 is ready for the next
message from the host controller (which will start at the next LOW to HIGH transition
on the CTRL pin), or is ready to execute the required command.
PCA9901_1
Product data sheet
Rev. 01 — 3 December 2009
© NXP B.V. 2009. All rights reserved.
5 of 27
5 Page 
NXP Semiconductors
PCA9901
One wire single LED driver
8.8.4 ‘Synchronization’ signal not generated after RUN ONCE command
The PCA9901 is waiting for the ‘Synchronization’ signal (rising edge of CTRL) after a
RUN ONCE command has been issued.
1. Once the RUN ONCE command has been decoded (end of the 1.5 ms window), a
time-out counter starts counting as long as CTRL stays LOW.
2. The time-out counter counts until it reaches the maximum allowed ON value. The
maximum allowed ON time is greater than or equal to 255 ms.
Remark: If CTRL goes HIGH before reaching the maximum counter value, the
time-out counter is reset and the PCA9901 runs the sequence once.
3. If the maximum time-out value is reached, the RUN ONCE command is automatically
aborted and the PCA9901 goes to Shutdown mode.
8.9 Current source generation
The LED output contains a constant current driver that will source a current that is
determined by an external resistor connected between ISET pin and GND. The current
can be set using the following formula:
IO
=
-(--1---.-2---3-----×-----4---0---0---)-
Rext
(1)
Rext can be chosen so that a maximum LED current value between 1 mA and 20 mA can
be programmed.
www.DataSheet4U.com
Remark: LED current accuracy is proportional to the accuracy and temperature
coefficient tolerance of Rext.
When no external resistor is connected between the ISET pin and GND, the LED output is
able to source 5 mA through a fully internal current source. It is automatically shut down
when an external resistor is connected to ISET.
Remark: The LED current accuracy is proportional to the tolerance and temperature
coefficient of the resistor.
Remark: To save power, the current source generator is only enabled when the LED
needs to be turned on.
8.10 Short-circuit and thermal protection
A short-circuit and thermal protection circuitry disables the LED output driver and the
current generator when a short occurs or when a high temperature condition has been
detected.
The circuitry is active during normal mode operation (Programing, RUN ONCE, RUN or
Bypass modes). When a fault condition is detected, the reference current circuitry (ISET)
and the LED output stage (LEDOUT) are automatically shut down. This will cause
LEDOUT to be OFF as long as the fault condition is present. The other analog blocks
(oscillator, voltage reference) are kept enabled as long as the PCA9901 is in normal mode
operation.
PCA9901_1
Product data sheet
The PCA9901 goes automatically to Power-down mode when it exits the programming,
RUN ONCE, RUN or Bypass modes.
Rev. 01 — 3 December 2009
© NXP B.V. 2009. All rights reserved.
11 of 27
11 Page | ||
| Páginas | Total 27 Páginas | |
| PDF Descargar | [ Datasheet PCA9901.PDF ] | |
Hoja de datos destacado
| Número de pieza | Descripción | Fabricantes |
| PCA9901 | One Wire Single LED Driver | NXP Semiconductors |
| Número de pieza | Descripción | Fabricantes |
| SLA6805M | High Voltage 3 phase Motor Driver IC. |
 Sanken |
| SDC1742 | 12- and 14-Bit Hybrid Synchro / Resolver-to-Digital Converters. |
 Analog Devices |
|
DataSheet.es es una pagina web que funciona como un repositorio de manuales o hoja de datos de muchos de los productos más populares, |
| DataSheet.es | 2020 | Privacy Policy | Contacto | Buscar |