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STFPC311
Front panel controller/driver with standby power management
Features

IC front panel controller/driver Timing power standby management controller IC power supply from 3.3V (VDD) to -30V (VSS) Integrated VFD driver and controller Infrared (IR) Remote Control (RC) Decoder (Philips or NEC format) Drives many display modes (12 segments/16 digits to 20 segments/8 digits) High voltage outputs (VDD - 33.3V max) No external resistors necessary for driver outputs (P-channel open- drain with pull-down resistor outputs) Key scanning (up to 12mm x 2mm matrix) Led ports (4 channels, 20mA, max) Serial interface (STB, CLK, DIN, and DOUT) communication protocol Dimming circuit (adjustable up to 8 steps) Supports auto-increment of display digit, which lightens the load on the MCU Programmable 8 hot keys for the IR remote control command Programmable 8 hot keys for key scan command Low power consumption in standby mode 2 general purpose input ports (SW1, SW2) Available in PQFP-52 package PQFP-52
Description
The STFPC311 is a complete, low-cost, integrated solution for controlling and driving a front panel Vacuum Fluorescent Display (VFD). It is ideal for decreasing power consumption in standby mode by reducing the application standby current to a minimum. It also contains a built-in remote control decoder module. While in the standby mode of operation, a valid key press or signal from infrared decoder will start a proper power-up see Figure 6 on page 12. The STFPC311 integrates a VFD controller with a driver that is run on a 1/8 to 1/16-duty factor. It consists of 12 segments output lines, 8 grid output lines, 8 shared segments/grid output drive lines, a display memory, a control circuit, and a key scan circuit. Serial data is input to the STFPC311 through the SPI Interface of a microcontroller (STB, DIN, DOUT, and CLK). Additionally, this IC can support 2 general purpose input switches (SW1 and SW2).

Features

DVD players VCD players AV equipment like Home Stereo POS Systems
Package PQFP-52
Order Codes
Part number STFPC311
Temperature range -40 to 85C
May 2006
Rev 1
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STFPC311
Contents
1 Functional description . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4
1.1 Block diagram . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4
2
Pin connection . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5
2.1 Pin description . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6
3
Initialization . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7
3.1 3.2 3.3 3.4 3.5 3.6 Normal mode of operation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7 Receive operation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7 Transmit operation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7 Standby or power-down mode . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8 IR Decoding . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8 Watchdog timer . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8
3.6.1 3.6.2 3.6.3 Watchdog timer operation during power-up . . . . . . . . . . . . . . . . . . . . . . . . . . . 9 Watchdog timer operation during power-down . . . . . . . . . . . . . . . . . . . . . . . 10 Watchdog timer operation during standby . . . . . . . . . . . . . . . . . . . . . . . . . . . 11
3.7
Flow charts
. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12
4 5
Display RAM address and display mode . . . . . . . . . . . . . . . . . . . . . . . . . . 15 Data . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 17
5.1 5.2 LED Port . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 17 SW Data . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 17
6
Commands . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 18
6.1 6.2 6.3 6.4 Configuration mode setting command . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 18 Data setting command . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 19 Address setting command . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 20 Display control and hotkey setting command . . . . . . . . . . . . . . . . . . . . . . . . 20
7
Programmable hotkeys . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 22
7.1 7.2 IR Remote control . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 22 Front panel keys . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 22
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STFPC311
8
Default status . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 24
8.1 8.2 Power-up default status . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 24 STANDBY status . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 24
9
Remote control protocols . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 25
9.1 9.2 9.3 RC-5 remote control . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 25 SPI interface IR data transmission . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 26 NEC remote control . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 26
10
Maximum rating . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 28
10.1 Power consumption estimation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 29
11 12 13 14 15 16
Electrical characteristics . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 30 Timing characteristics . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 31 Serial communication format . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 32 Typical application diagram . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 35 Package mechanical data . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 36 Revision history . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 38
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1 Functional description
STFPC311
1
Functional description
The STFPC311 receives serial data from the microcontroller through the SPI interface, latches the data, and then masks the inputs from the MCU. This data consists of commands followed by data. There are 4 types of commands:

configuration, data, address, and display.
The STFPC311 integrates the supply standby power management functionality, remote control decoder, and a 28-bit VFD driver. Microcontrollers usually run the first two tasks. This device reduces the stand-by power consumption of the whole Front Panel application as well as the hardware by integrating the infrared (IR) remote control decoder. A dedicated supply voltage powers the STFPC311 directly from the main supply board. When power is plugged in, control of the power supply management is done using the following pins: 1. 2. 3. STBY, IR_DATA_IN, and READY.
1.1
Figure 1.
Block diagram
Block diagram
IR_DATA_IN READY/STBY_n Remote Control Decoder & Stand By Function STBY MUTE Watchdog Timer
DIN DOUT CLK STB VDD
Command Decoder SPI Serial I/F 20-bit Output Latch
20
12
Segment Drivers
SEG1/KS1 SEG12/KS2
Display Memory (20 x 16)
8 8 Multiplexed Drivers SEG13/GRID16
OSC ROSC SW1 SW2 KEY1 KEY2 2-bit Latch
Timing Generator Key Scan and Dimming Circuit
Data Selector
SEG20/GRID9
8 Grid Drivers Key Data Memory (2 x 12) 16-bit Shift Register LED1 LED2 LED3 LED4 GRID8 GRID1
16
8
2 2 4-bit Latch
VDD GND VSS (+3.3V) (0V) (-30V)
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STFPC311
2 Pin connection
2
Figure 2.
Pin connection
Connection diagram (top view PQFP-52)
STFPC311
Note:
For a description of the behavior of each pin, refer to the Table 1: Pin description on page 6.
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2 Pin connection
STFPC311
2.1
Table 1.
Pin N 1 2, 3 4
Pin description
Pin description
Symbol OSC SW1, SW2 MUTE Type I I O Name and function This is the oscillator input pin. Connect this pin to an external resistor. General purpose switch input ports. High level indicates mute status for audio. Low level indicates normal working.Note 1 there is a typo. Pin5 and name is STBY. Standby output to put the MCU in low power mode. It is a command to the main power board. High level indicates stand-by status. Low level indicates normal working. Note 1 Connect this pin to system GND. Input data to these pins from external keyboard are latched at end of the display cycle (maximum keyboard size is 12 x 2). High level on this pin means that main board chip has been working normally.Note 1 This pin should never float. It is recommended have a pull-down resistor on this input. Remote control input. Feeds the IR data from photodiode to this pin. Segment output pins (dual function as key source). VFD outputs high voltage pull-down level. VDD--33.3V max. These pins are selectable for segment or grid driving. Grid output pins. 3.3V 0.3V Core main supply voltage. Not used. Left unconnected. Grid output pins. Initializes the serial interface at the rising or falling edge to make the STFPC31 wait for reception of command. The data input after the falling edge of STB is processed as a command. While the command data is processed, current processing is stopped, and the serial interface is initialized. While STB is high, CLK is ignored and any instruction from the MCU is neglected. Reads serial data at the rising edge, and outputs data at the falling edge. Inputs serial data at the rising edge of the shift clock, starting from the lower bit. Outputs serial data at the faling edge of the shift clock, starting from the lower bit. This is the N-channel opendrain output pin. CMOS outputs (20mA, max).
5S
TBY
O
7 8, 9
GND KEY1, KEY2
POWER I
10 1 14 to 25 12, 26 27 to 34 35 to 37 6, 13,38 39 40 to 44
READY IR_DATA_IN SEG1/KS1 to SEG12/KS12
VSS
I I O POWER O O POWER O O
SEG13/GRID16 to SEG20/GRID9 GRID8 to GRID6
VDD
NC GRID5 to GRID1
45
STB
I
46 47 48 49-52
CLK
DIN DOUT
I I O O
LED1, LED2, LED3, LED4
Note: 1 For a detailed behavioral description of these pins, refer to the "STFPC311 Timing Power Stand-by Sequencer Flow-Chart". See Table 6 on page 12
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STFPC311
3 Initialization
3
Initialization
After the power is plugged in, the device will supply power to all of the components (including the host processor) by setting STBY to logic low in order to allow the host processor to program the STFPC311. Once the STBY is set to low, the watchdog timer starts to count up to 10s (10s is the default value of the watchdog timer upon power-up). When the READY is asserted within this time, it indicates that the system has booted up well. If the READY pin is not asserted (logic high) within this time (10s), the STFPC311 will put the system into standby mode again by setting STBY to logic high. If READY is detected as logic high, the watchdog timer will be turned OFF. The main processor should program the remote control hot key and initialize the other parameters of the STFPC311 in preparation for normal operation before the system goes into standby mode. After all of the STFPC311 configuration is finished, the host processor may set the READY to low so that the STFPC311 enters standby mode. The STFPC311 then sets the MUTE pin to logic high to mute the audio output as well as the STBY pin to logic high. As a consequence of this action, the main supply voltage is turned off.
3.1
Normal mode of operation
After the power is plugged in, the device will supply power to all of the components (including the host processor) by setting STBY to logic low in order to allow the host processor to program the STFPC311. Once the STBY is set to low, the watchdog timer starts to count up to 10s (10s is the default value of the watchdog timer upon power-up). When the READY is asserted within this time, it indicates that the system has booted up well. If the READY pin is not asserted (logic high) within this time (10s), the STFPC311 will put the system into standby mode again by setting STBY to logic high. If READY is detected as logic high, the watchdog timer will be turned OFF. The main processor should program the remote control hot key and initialize the other parameters of the STFPC311 in preparation for normal operation before the system goes into standby mode. After all of the STFPC311 configuration is finished, the host processor may set the READY to low so that the STFPC311 enters standby mode. The STFPC311 then sets the MUTE pin to logic high to mute the audio output as well as the STBY pin to logic high. As a consequence of this action, the main supply voltage is turned off.
3.2
Receive operation
In receive condition, the STFPC311 waits for a valid command from the MCU. The receive circuit of STFPC311 receives 8 bit serial data, latches the data and then masks the inputs from the MCU. Refer to Figure 28 on page 32 for receive timing.
3.3
Transmit operation
In transmit condition, the STFPC311 sends the 8-bit serial data (LSB transmitted first) whenever a key is pressed or IR data is received. STFPC311 transmits data on the falling edge of CLK. Refer to Figure 29 on page 32 for transmit timing.
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3 Initialization
STFPC311
3.4
Standby or power-down mode
Once the STFPC311 detects the status change of the READY to a logic low or after the preset waiting time (1s to 15s) has elapsed, the STFPC311 sets the STBY pin to a logic high to turn off the power. The MUTE signal is set to high before the power is turned off. The STFPC311 always senses the level on the READY pin during normal operation.
3.5
IR Decoding
Encoded IR data from photodiode is supplied to the IR_DATA_IN input pin. The data is decoded by the internal remote control decoder module of STFPC311. In standby mode, the remote control decoder recognizes a set of predefined commands (such as STANDBY, PLAY, and OPEN/CLOSE), and takes appropriate action to manage the power supply. These predefined commands are known as "hot keys" and are programmable. The decoded IR commands are passed on to the main processor through the SPI interface by sending 3 bytes of data on the DOUT pin.
3.6
Watchdog timer
The watchdog timer is used to detect an out-of-control microprocessor. The watch dog timer is implemented in the STFPC311 to detect the abnormal processor behavior or processor-hung condition. The default state of the watchdog timer is 10s when the device powers-up. It is initialized by writing to the watchdog register and can be programmed to up to 15s (4-bit watchdog timer, present in the configuration mode setting command). If the processor does not reset the timer within the specified period, the STFPC311 will put the entire system into standby mode to reset the appliance that has stopped abnormally. The action to take when the watchdog timer has reached its count is to set the Watchdog Action register. The watchdog timer can be reset by the host processor by sending a command to reset the watchdog timer. The time-out period then starts over again. If the processor needs to be reset as a result of a hung condition (signalled using the STBY output of the STFPC311), the watchdog timer uses the amount of the time-out programmed into the Watchdog Register by the user to generate an interrupt.
Note:
The accuracy of the timer is within 10% the selected resolution. This depends on the value of the external bias resistor, as it determines the internal clock frequency. The watchdog function is automatically set to 10s upon power-up and the Watchdog Interrupt is cleared. This boot-up watchdog timer is used to make sure that if the host processor hangs during the first boot-up, the STFPC311 will put the system to standby mode. During the first boot-up, the watchdog timer is disabled after the first READY signal is received.
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STFPC311
3 Initialization
3.6.1
Figure 3.
Watchdog timer operation during power-up
Power-up condition
Note:
Watchdog timer is turned off by default upon READY assertion. If Watchdog is to be kept on during READY high condition, the WDG registers must be set accordingly by proper commands through SPI bus. In this power-up condition, the watchdog timer is triggered by internal POR pulse. During power-up, the watchdog timer value is 10s.
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3 Initialization
STFPC311
3.6.2
Figure 4.
Watchdog timer operation during power-down
Power-down condition
Note:
The watchdog timer can be kept on during normal conditions when READY is high (depending on the user's settings). In this condition, the watchdog timer can be disabled or enabled. If the watchdog timer is enabled, the timer needs to be cleared before the programmed count of the timer is reached. If the programmed count is reached, the STBY will be asserted.
Caution: It is advisable not to enable the watchdog timer during normal operation.
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STFPC311
3 Initialization
3.6.3
Watchdog timer operation during standby

When a hot-key signal is detected either from the front panel or remote control during standby, the STBY de-asserts. The de-assertion of the STBY triggers the watchdog timer. The timer value is the programmed value that is set by the user (1s-15s). If the user did not change the value before entering standby, then it remains 10s. Also note: that The watchdog timer is off when the STFPC311 is in the standby mode to save power. Standby condition
3 a ) S ta n d b y C o n d itio n (N o rm a l b e h a vio r )
H o t ke y co m m a n d fro m IR o r K e y p a d fo r w a ke u p W D G tim e r trig g e rs
Figure 5.
STBY
READY R E A D Y a sse rts w ith in p ro g ra m m e d tim e r va lu e (1 s-1 5 s) MUTE
3b ) S ta n d b y C o n d itio n ( A b n o rm a l b e h a vio r, p ro c e s s o r is n o t re s p o n d in g)
H o t ke y co m m a n d fro m IR o r K e y p a d fo r w a ke u p W D G tim e r trig g e rs S ig n a ls S T B Y a fte r W D G co u n t is o ve r
STBY
READY MUTE
R E A D Y co n tin u e s to re m a in lo w
The watchdog timer is triggered by a de-assertion of the STBY signal or by the internal Power-on Reset signal. It is not affected by the STB pin.
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3 Initialization
STFPC311
3.7
Figure 6.
Flow charts
Timing power standby sequencer flow chart
* Programmable from 1 to 15s. FPK = Front Panel Keys
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STFPC311
Figure 7. IR RC command and front panel key operation flowchart.
3 Initialization
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3 Initialization
STFPC311
Figure 8.
Watchdog timer first power-up operation
Figure 9.
Watchdog timer operation
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STFPC311
4 Display RAM address and display mode
4
Display RAM address and display mode
The display RAM stores the data transmitted from an external device to the STFPC311 through the serial interface and is assigned addresses, in units of 8-bits see :Table 2. Only the lower 4 bits of the addresses assigned to Seg17 through Seg20 are valid, the higher 4 bits are ignored.
Note:
The common grid/segment outputs are grid-based. The grid has to be enabled before any segments can be turned on. If data is written for a segment before enabling its grid, there is nothing on the display. Table 2.
Seg1 00 HL 03 HL 06 HL 09 HL 0C HL 0F HL 12 HL 15 HL 18 HL 1B HL 1E HL 21 HL 24 HL 27 HL 2A HL 2D HL b0 XX HL Lower 4 bits b3 b4 XX HU Higher 4 bits
Assigned addresses
Seg4 00 HU 03 HU 06 HU 09 HU 0C HU 0F HU 12 HU 15 HU 18 HU 1B HU 1E HU 21 HU 24 HU 27 HU 2A HU 2D HU b7 Seg8 01 HL 04 HL 07 HL 0A HL 0D HL 10 HL 13 HL 16 HL 19 HL 1C HL 1F HL 22 HL 25 HL 28 HL 2B HL 2E HL Seg12 01 HU 04 HU 07 HU 0A HU 0D HU 10 HU 13 HU 16 HU 19 HU 1C HU 1F HU 22 HU 25 HU 28 HU 2B HU 2E HU Seg16 02 HL 05 HL 08 HL 0B HL 0E HL 11 HL 14 HL 17 HL 1A HL 1D HL 20 HL 23 HL 26 HL 29 HL 2C HL 2F HL Seg20 DIG1 DIG2 DIG3 DIG4 DIG5 DIG6 DIG7 DIG8 DIG9 DIG10 DIG11 DIG12 DIG13 DIG14 DIG15 DIG16
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4 Display RAM address and display mode
STFPC311
The data of each key is stored READ by a read command, starting from the least significant bit. see Figure 11.. When the most significant bit of data (Seg12b7) has been read, the least significant bit of the next data (Seg1b0) is read. Figure 10. Key matrix (12 x 2 configuration) and key-input data storage RAM
Figure 11. Key storage and READ access
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STFPC311
5 Data
5
5.1
Data
LED Port
Data is written to the LED port by a WRITE command, starting from the least significant bit of the port see Figure 12. When a bit of this port is set to 0, the corresponding LED lights up; when the bit is set to a 1, the LED turns off. The data of Bits 5 through 8 are ignored. Upon first power-up, all of the LEDs are turned off. Figure 12. LED port data WRITE command order
5.2
SW Data
The SW data are read by the appropriate READ command, starting from the least significant bit see Figure 13. Bits 3 through 8 of the SW data are 0. Figure 13. SW data READ Command order
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6 Commands
STFPC311
6
Commands
A command sets the display mode and status of the VFD driver. The first 1-byte input to the STFPC311 through the DIN pin after the STB pin goes low is regarded as a command. If STB is set to high while commands/data are transmitted, the serial communication is initialized and the commands/data being transmitted are invalid (however, the commands/data already transmitted remain valid).
6.1
Configuration mode setting command
This command initializes the STFPC311 and performs any one of the following functions see Figure 14. a) Selects the number of segments and number of grids (1/8 to 1/16 duty, 12 segments to 20 segments). When this command is executed, the display is turned off. To resume display, the Display ON command must be executed. If the same mode is selected, nothing is performed. Selects the remote control protocol to use. Sets the watchdog timer. The watchdog timer is configurable from 1s to 15s or turned off completely. Sets the watchdog action to perform when the watchdog timer counts. Two actions are allowed: no action, and set STBY to (logic) high level.
b) c) d)
Figure 14. STFPC311 Configuration mode setting command order
Table 3.
STFPC311 Configuration mode bit 3 through bit 0 settings
Note:
Based on Bit 5 through Bit 4 settings.
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STFPC311
Upon power application, the following modes are selected:

6 Commands
Display Mode Setting: the 16-digit, 12-segment mode is selected (default: display off and key-scan on). Remote Control Protocol Setting: RC-5. Watchdog Timer Setting: Turned on with 10s. After the first command is processed by STFPC311, the watchdog timer is turned off until it is turned on by the host. Watchdog action: Issue Standby.
6.2
Data setting command
This command sets the data WRITE and READ modes see Figure 15.
Figure 15. STFPC311 Data setting command order
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6 Commands
STFPC311
When the application is powered-up, the normal operation mode and address increment mode is set with the default display memory address set to 00H. In the auto-increment address mode, the address command is sent once, followed by the data bytes. Alternatively, the data command can be sent, followed by the data bytes. In this case, when new display data is to be written, the last value of the address will be used and then incremented. Upon reaching the last display memory address, the address jumps to 00H. For fixed address mode, the address command has to be sent, followed by the display data. When next byte of data is to be written, the address command has to be sent again before the new display data byte. For RC-5 data reception (after the photodiode), a binary 1 is represented by a high-to-low transition, and a binary 0 is represented by a low-to-high transition. For RC-6 (Mode 0) data reception, a binary 1 is represented by a low-to-high transition, and a binary 0 is represented by a high-to-low transition. Whenever Bit 5 is a `1', the watchdog timer is reset.
6.3
Address setting command
This command sets an address of the display memory. If address 30H or higher is set, the data is ignored until a correct address is set. Figure 16. STFPC311 Address Setting Command Order
6.4
Display control and hotkey setting command
When the application is powered-up, the 1/16-pulse width is set and the display is turned OFF. See Figure 17 and Figure 4. All hot keys are disabled.
Figure 17. STFPC311 Display control and hot key setting command order
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STFPC311
Table 4. STFPC311 Address setting mode bit 3 through bit 0 settings
6 Commands
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7 Programmable hotkeys
STFPC311
7
7.1
Programmable hotkeys
IR Remote control
Eight (8) commands are user programmable for hot key functions. The address of the appliance (8-bit) is stored first into the internal RAM. Then, the command for the hot keys are programmed into the internal RAM. Each hot key memory address could accommodate one byte (8-bits). Usually one byte is reserved for one command. The RC data is only cleared when the READY is pulled low (system goes into STANDBY state).
7.2
Front panel keys
Eight out of 24 keys are user programmable for hot key functions. Only keys from KS1 to KS4 can be programmed. Figure 18. Programmable hot keys (only KS1 to KS4, Box FPK1)
8 hot keys are to be placed in each address location as indicated by the hotkey setting command. Figure 19. HOTKEY setting command address locations (8 hot keys)
For example, to store (Seg2/Key2) at the first location of the hot key RAM, the following commands are sent:

10110000 (command+address), and 00010000 (hot key mask). 10110000 (command+address), and 00110010 (hot key mask).
To store (Seg2/Key1), (Seg2/Key2), and (Seg4/Key1), the following commands are sent:

The same commands apply to FPK2 and FPK3 programming. Note: Note: Reading the hot key values immediately upon STBY de-assertion is recommended. If they are not read within the watchdog preset timer value, the hot key data is cleared.
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STFPC311
Figure 20. Recommended software flow
7 Programmable hotkeys
Note:
Resetting the front panel controller at 3/4 of the set watchdog time is recommended.
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8 Default status
STFPC311
8
8.1
Default status
Power-up default status
Table 5.
S. N 1 2 3 4 5 6 7 8 9 10 Display Key-scan IR Display mode Display address RC Protocol LED Dimming Hot Kets (IR and FP) Watchdog timer
Default States
Functions OFF ON ON 12 Seg/16Bit 00H DC-5 OFF 1/16 Duty factor Disabled 10s Default Status
8.2
STANDBY status
The display remains ON during STANDBY only if the -20V is present. If the -20V is absent, the display turns OFF. When the display wakes up from STANDBY and -20V is applied, the display turns ON with previous value. Switching off the display before entering the STANDBY state is recommended. When the same display configuration command is sent, the display remains ON. When the display configuration command is changed, the display is OFF. Only hot key detection can wake the system up from STANDBY condition.
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STFPC311
9 Remote control protocols
9
9.1
Remote control protocols
RC-5 remote control
RC-5 remote control protocol is based on Bi-phase (also known as Manchester) encoding as shown in Figure 21.
Note:
The encoding is set with reference to the IR_DATA_IN signal (after the photo diode). The MSB is transmitted first see Figure 22.
The first two Start bits (S1 and S2) are synchronization bits. For normal operation, they are always set to '11' on the transmission side. After the photo diode, there is one inversion. The data at the IR_DATA_IN of the STFPC311 is shown in Figure 23 on page 25 The next bit is the Toggle bit. This bit is inverted each time a key on the remote control is pressed. Bits A1and A5 are the Address bits. The address bits indicate the intended application that the remote control protocol is used for. Bits C1..C6 are the Command bits. The command bits instruct the STFPC311 as to what action is to be taken. The data representing the RC-5 protocol is sent as a byte of data which consists of a Toggle bit and a `0' bit followed by 6 bits of Command data.

Figure 21. Bi-phase encoding
Figure 22. RC-5 protocol frame
Figure 23. RC-5 reception example
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9 Remote control protocols
STFPC311
9.2
SPI interface IR data transmission
The IR data is sent on the DOUT pin of the SPI interface when the micro controller issues a IR data read command. The data is sent in 3 bytes with LSB transmitted first as shown in the Figure below: The RC data consists of RC address, start bit, toggle bit and the RC command received. The extra bits are stuffed with 1's to make it a 3-byte packet. These extra bits at the end of the packet should be ignored. Figure 24. RC-6 protocol frame
The RC data consists of RC address, start bit, toggle bit and the RC command received. The extra bits are stuffed with 1's to make it a 3-byte packet. These extra bits at the end of the packet should be ignored.
9.3
NEC remote control
This remote control protocol uses pulse distance modulation. Each bit consists of a high level of fixed time "t", followed by a low level that varies in width. A space that is "t" represents a logic '0' and a space that is "3t" represents a logic '1'. t = 0.56ms. The LSB is transmitted first as shown in Figure 25 Figure 25. Pulse distance modulation.
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STFPC311
Figure 26. NEC protocol transmission waveforms
9 Remote control protocols
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10 Maximum rating
STFPC311
10
Maximum rating
Stressing the device above the rating listed in the "Absolute Maximum Ratings" table may cause permanent damage to the device. These are stress ratings only and operation of the device at these or any other conditions above those indicated in the Operating sections of this specification is not implied. Exposure to Absolute Maximum Rating conditions for extended periods may affect device reliability. Refer also to the STMicroelectronics SURE Program and other relevant quality documents. Table 6.
Symbol VDD VSS VI1 VO2 IO1 IO2 PD TA TSTG
Absolute maximum rating ( TA = 25 C, VSS = 0V )
Parameter Logic Supply Voltage Driver Supply Voltage Logic Input Voltage VFP Driver Output Voltage LED Driver Output Current VFP Driver Output Current Power Dissipation Operating Ambient Temperature Storage Temperature Value -0.5 to +7.0 VDD + 0.5 to VDD - 40 -0.4 to VDD + 0.5 VSS - 0.5 to VDD+ 0.5 +25 -40 (grid) -15 (segment) 1200 (1) -40 to +85 -65 to +150 Unit V V V V mA mA mA C C
1. Derate at -9.6 mW/C at TA = 25 C or higher
Table 7.
Symbol VDD VIH VIL VSS
Recommended operating conditions (TA = -20 to +70 C, VSS = 0V)
Parameter Logic Supply Voltage High-Level Input Voltage Low-Level Input Voltage Driver Supply Voltage Min 3.0 0.7VDD 0 0 Typ 3.3 Max 3.6 VDD 0.3 VDD VDD-33.3 Unit V V V V
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STFPC311
10 Maximum rating
10.1
Power consumption estimation
The maximum power consumption is comprised of the Vacuum Florescent Display (VFD) driver dissipation, Load Resistance (RL), LED driver dissipation, and dynamic power consumption. PMAX = VFD + RL + LED + PDYN Where,

PMAX = maximum power consumption, VFD = Vacuum Florescent Display driver dissipation, RL = load resistance, LED = LED driver dissipation, and PDYN = dynamic power consumption.
If the segment current (ISEG) = 3mA, grid current (IGRID) = 15mA, and the LED current = 20mA, then: FIP = (#segments x 6) + [#grids/(#grids +1)] x 30mW, RL dissipation = (VDD - VSS)2 / 50(segment + 1mW), LED driver dissipation = #LEDs x 20mW, and PDYN = VDD x 5mW. To finish this example: FIP driver dissipation = 16 x 6 + 12/13 x 30 = 124mW RL dissipation = 33.32/50 x 17 = 377mW LED driver dissipation = 2 x 20 = 40 PDYN = 3.3 x 5 = 16.5mW The maximum power consumption (Total) = 557.5mW Where, VSS = -30V, VDD = 3.3V, and the application is in 16-segment, 12-digit mode.
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11 Electrical characteristics
STFPC311
11
Electrical characteristics
Table 8.
Symbol VOH1 VOL1 VOL2 IOH21 IOH22 IOLEAK RL I VIH VIL VH IDD(DYN)
Electrical specifications (TA = -20 to +70C, VDD = 3.3V, VSS = 0V, VSS = VDD - 33.3V)
Parameter High-Level Output Voltage Low-Level Output Voltage Low-Level Output Voltage High-Level Output Current High-Level Output Current Driver Leakage Current Test conditions LED1 - LED4, IOH1 = -1mA LED1 - LED4, IOH2 = 20mA DOUT, IOL2 = 4mA VO = VDD - 2V, Seg1to Seg12 VO = VDD - 2 V, Grid1to Grid8, Se13g/Grid16to Seg20/Grid9 VO = VDD - 33.3 V, driver off 50 100 -3 -15 -10 150 1 0.7VDD 0.3VDD CLK, DIN, STB Under no load, display off 0.35 5 Min. 0.9VDD 1 0.4 Typ. Max. Unit V V V mA mA A k A V V V mA
Output Pull-Down Resistor Driver output Input Current High-Level Input Voltage Low-Level Input Voltage Hysteresis Voltage Dynamic Current Consumption VI= VDD or VSS
Table 9.
Symbol tOSC tPLZ tPZL tTZH1
Switching characteristics (TA = -20 to +70 C, VDD = 3.3 V, VSS = -30 V)
Parameter Oscillation Frequency Propagation Delay Time Test conditions R = 33K 5% CLK DOUT CL = 15pF, RL = 10K Seg1 to Seg12 Rise Time CL = 300pF Grid1 to Grid8, Seg13/Seg16 to Seg20/Grid9 Min. 350 Typ. 500 Max. 650 300 100 2 Unit kHz ns ns s s s MHz pF
tTZH2 tTHZ fMAX CI Fall Time Maximum Clock Frequency Input Capacitance
0.5
CL = 300pF, Segn, Gridn Duty = 50%
120 1 15
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STFPC311
12 Timing characteristics
12
Timing characteristics
Table 10. Timing characteristics ( VDD= 3.3V, TA= -20 to 70C, unless otherwise noted. Typical values are at TA= 25C )
Values Symbol PWCLK PWSTB tSETUP tHOLD tCLK-STB tWAIT Parameter Clock Pulse Width Strobe Pulse Width Data Setup Time Data Hold Time Clock-Strobe Time Wait Time (1) CLK CLK STB CLK Test conditions Min. 400 1 100 100 1 1 Typ. Max. ns s ns ns s s Unit
1. Refer to page on Serial Communication Format.
The pulse width of the segment signal is derived from the oscillator frequency. The value can be modified by trimming ROSC. One cycle of key scanning consists of one frame and data of 12 x 2 matrices are stored in RAM. Note: The key scan is only at the end of the frame when the display is ON. When the display is OFF, the key scan takes place continuously. The grid is turned off during the key scan. Figure 27. Key scanning and display timing
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13 Serial communication format
STFPC311
13
Serial communication format
When data is read, a wait time (tWAIT) of 1s is necessary within the rising edge of the eighth clock that has set the command, and the falling edge of the first clock that has read the data. This is required by the STFPC311 to process its internal commands/data (See Figure 28)
Caution: Care must be taken to connect an external pull-up resistor to this pin (1k to 10k) because the
DOUT pin is an N-channel, open drain output pin (see Figure 29). Figure 28. Recption (Command/data WRITE)
Figure 29. Data transmission (data READ)
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STFPC311
Figure 30. Switching characteristic waveforms
13 Serial communication format
fO SC
O SC 50%
P W STB
STB P W CLK P W C LK t C L K -S T B
CLK tSETUP D IN tPZL tPLZ t H O LD
D OUT tTHZ
90% 10%
tTZH
S n/ G n
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13 Serial communication format

STFPC311
Command 1: sets display mode Command 2: sets data Command 3: sets address Data 1 to n: transfers display data (22 bytes max.) Command 4: controls display
Figure 31. Updating display memory by incrementing address

Command 1: sets data Command 2: sets address Data: display area
Figure 32. Updating specific address
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STFPC311
14 Typical application diagram
14
Typical application diagram
Figure 33. Typical application circuit
R5 R6
12 x 2 KEY B O AR D
D1
D 12
V DD
KEY 1 V DD
KEY 2
SEG 1/K1
SEG 12/K12
V FD + C1 C2
1 2 3 4 5 6 7 8 9
Ef
8 G rids/Segments
R OSC
O SC STB C LK D IN D OUT IR _D AT A_IN R EAD Y /STBY _n NC M U TE STBY
S13/G 16 ~ S20/G 9
ST FPC 311
8 G rids G1 ~ G8
< < < < < < < < < < < <
R1
LED 1 LED 2 LED 3 LED 4 V SS V SS
R2 R3 R4
10 11 12
V DD 3.3V0.3V V SS * -30V GND GND
V DD C3 C4 +

ROSC = 33k 1% for oscillator resistor; R1 ~ R4 = 0.75 ~ 1.2k; R5, R6 = 10k for external keyboard pull-down resistor; C1 = 33F-25V electrolytic; C2 = 0.01 ~ 0.1F-25V ceramic; C3 = 0.01 ~ 0.1F-63V ceramic; C4 = 33F-63V electrolytic; D1 ~ D12 = 1N4148; Ef = filament voltage according with the VFD specs; VDD = 3.3V 10%;
* VSS = down to VDD - 33.3V.
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15 Package mechanical data
STFPC311
15
Package mechanical data
In order to meet environmental requirements, ST offers these devices in ECOPACK(R) packages. These packages have a Lead-free second level interconnect. The category of second Level Interconnect is marked on the package and on the inner box label, in compliance with JEDEC Standard JESD97. The maximum ratings related to soldering conditions are also marked on the inner box label. ECOPACK is an ST trademark. ECOPACK specifications are available at: www.st.com.
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STFPC311
Table 11.
15 Package mechanical data
PQFP52 - 10x10x2 mm. plastic quad flatpack, package mechanical data
Figure 34. Package dimensions
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16 Revision history
STFPC311
16
Revision history
Table 12.
Date 09-May-2006
Revision history
Revision 1 First release Change
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STFPC311
16 Revision history
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