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LED Driver IC
PT6955
DESCRIPTION
PT6955 is an LED Controller driven on a 1/4 to 1/7 duty factor. Twelve/nine segment output lines, 4 to 7 grid output lines, one display memory, control circuit are all incorporated into a single chip to build a highly reliable peripheral device for a single chip microcomputer. Serial data is fed to PT6955 via a three-line serial interface. Housed in a 24-pin SOP, PT6955's pin assignments and application circuit are optimized for easy PCB Layout and cost saving advantages.
FEATURES
* * * * * CMOS Technology Low Power Consumption 8-Step Dimming Circuitry Serial Interface for Clock, Data Input, Strobe Pins Available in 24-pin, SOP
APPLICATION
* Micro-computer Peripheral Device
PT6955 V1.5
-1-
June, 2005
Tel: 886-2-66296288 Fax: 886-2-29174598 URL: http://www.princeton.com.tw
LED Driver IC
PT6955
BLOCK DIAGRAM
PT6955 V1.5
-2-
June, 2005
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LED Driver IC
PT6955
INPUT/OUTPUT PORT CONFIGURATION
The schematic diagrams of the input and output circuit of the logic section are shown below. Input Pins: CLK, STB & DIN Output Pins: SG10/GR7, SG11/GR6, SG12/GR5
VDD
GND
GND
Output Pins: GR1 to GR4
VDD
Output Pins: SG1 to SG9
VDD
GND
GND
PT6955 V1.5
-3-
June, 2005
Tel: 886-2-66296288 Fax: 886-2-29174598 URL: http://www.princeton.com.tw
LED Driver IC
PT6955
PIN CONFIGURATION
PIN DESCRIPTION
Pin Name
OSC DIN CLK STB VDD SG1 ~ SG9 SG10/GR7 ~ SG12/GR5 GND GR4 ~ GR1
I/O
I I I I O O O
Description
Pin No.
Oscillator Input Pin A resistor is connected to this pin to determine 1 the oscillation frequency Data Input Pin This pin inputs serial data at the rising edge of the 2 shift clock (starting from the lower bit) Clock Input Pin 3 This pin reads serial data at the rising edge. Serial Interface Strobe Pin The data input after the STB has fallen is processed 4 as a command. When this pin is "HIGH", CLK is ignored. Power Supply 5, 18 Segment Output Pins 6 ~ 14 (p-channel, open drain) Segment Output Pin/Grid Output Pin 15 ~ 17 (CMOS Output) Ground Pin 19, 24 Grid Output Pins (n-channel, open drain) 20 ~ 23
PT6955 V1.5
-4-
June, 2005
Tel: 886-2-66296288 Fax: 886-2-29174598 URL: http://www.princeton.com.tw
LED Driver IC
PT6955
FUNCTION DESCRIPTION
COMMANDS
A command is the first byte (b0 to b7) inputted to PT6955 via the DIN Pin after STB Pin has changed from "HIGH" to "LOW" State. If for some reason the STB Pin is set to "HIGH" while data or commands are being transmitted, the serial communication is initialized, and the data/commands being transmitted are considered invalid.
COMMAND 1: DISPLAY MODE SETTING COMMANDS
PT6955 provides 4 display mode settings as shown in the diagram below: As stated earlier a command is the first one byte (b0 to b7) transmitted to PT6955 via the DIN Pin when STB is "LOW". However, for these commands, Bit No. 3 to Bit No.6 (b2 to b5) are ignored, Bit No.7 & Bit No.8 (b6 to b7) are given a value of "0". The Display Mode Setting Commands determine the number of segments and grids to be used (1/4 to 1/7 duty, 12 to 9 segments). When these commands are executed, the display is forcibly turned off. A display command "ON" must be executed in order to resume display. If the same mode setting is selected, no command execution is take place, therefore, nothing happens. When Power is turned "ON", the 7-Grid, 9-Segment Mode is selected. MSB 0 0 LSB b1 b0
Not Relevant
Display Mode Settings: 00: 4 digits, 12 segments 01: 5 digits, 11 segments 10: 6 digits, 10 segments 11: 7 digits, 9 segments
PT6955 V1.5
-5-
June, 2005
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LED Driver IC COMMAND 2: DATA SETTING COMMANDS
PT6955
The Data Setting Commands executes the Data Write Mode for PT6955. The Data Setting Command, the bits 5 and 6 (b4, b5) are ignored, bit 7 (b6) is given the value of "1" while bit 8 (b7) is given the value of "0". Please refer to the diagram below. When power is turned ON, bit 4 to bit 1 (b3 to b0) are given the value of "0". MSB 0 1 LSB b3 b2 b1 b0 Data Write Mode Settings: 00: Write Data to Display Mode Address Increment Mode Settings (Display Mode) 0: Increment Address after Data has been Written 1: Fixed Address Mode Settings: 0: Normal Operation Mode 1: Test Mode
Not Relevant
PT6955 V1.5
-6-
June, 2005
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LED Driver IC COMMAND 3: ADDRESS SETTING COMMANDS
PT6955
Address Setting Commands are used to set the address of the display memory. The address is considered valid if it has a value of "00H" to 0DH". If the address is set to 0EH or higher, the data is ignored until a valid address is set. When power is turned ON, the address is set at "00H". Please refer to the diagram below. MSB 1 1 LSB b3 b2 b1 b0 Address: 00H to 0DH
Not Relevant
Display Mode and RAM Address Data transmitted from an external device to PT6955 via the serial interface are stored in the Display RAM and are assigned addresses. The RAM Addresses of PT6955 are given below in 8 bits unit.
SG1 SG4 00HL 02HL 04HL 06HL 08HL 0AHL 0CHL b0 xxHL Lower 4 bits SG5 SG8 00HU 02HU 04HU 06HU 08HU 0AHU 0CHU b3 b4 xxHU Higher 4 bits SG9 SG12 01HL 03HL 05HL 07HL 09HL 0BHL 0DHL DIG1 DIG2 DIG3 DIG4 DIG5 DIG6 DIG7 b7
PT6955 V1.5
-7-
June, 2005
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LED Driver IC COMMAND 4: DISPLAY CONTROL COMMANDS
PT6955
The Display Control Commands are used to turn ON or OFF a display. It also used to set the pulse width. Please refer to the diagram below. When the power is turned ON, a 1/16 pulse width is selected and the displayed is turned OFF. MSB 1 0 LSB b3 b2 b1 b0 Dimming Quantity Settings: 000: Pulse width = 1/16 001: Pulse width = 2/16 010: Pulse width = 4/16 011: Pulse width = 10/16 100: Pulse width - 11/16 101: Pulse width = 12/16 110: Pulse width = 13/16 111: Pulse width = 14/16 Display Settings: 0: Display Off 1: Display On
Not Relevant
PT6955 V1.5
-8-
June, 2005
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LED Driver IC
PT6955
DISPLAY TIMING WAVEFORM
SERIAL COMMUNICATION FORMAT
The following diagram shows the PT6955 serial communication format.
PT6955 V1.5
-9-
June, 2005
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LED Driver IC
PT6955
SWITCHING CHARACTERISTICS WAVEFORM
where: PWCLK (Clock Pulse Width) 400ns tsetup (Data Setup Time) 100ns tCLK-STB (Clock - Strobe Time) 1s tTZH (Rise Time) 1 s tTZL 1s
PWSTB (Strobe Pulse Width) 1s thold (Data Hold Time) 100ns tTHZ (Fall Time) 10s fosc = Oscillation Frequency tTLZ 10 s
PT6955 V1.5
- 10 -
June, 2005
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LED Driver IC
PT6955
APPLICATIONS
Display memory is updates by incrementing addresses. Please refer to the following diagram.
The following diagram shows the waveforms when updating specific addresses.
PT6955 V1.5
- 11 -
June, 2005
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LED Driver IC
PT6955
RECOMMENDED SOFTWARE FOLWCHART
START Delay 200 ms
SET COMMAND 2 (WriteData)
SET COMMAND 3 Clear Display RAM (See Note 5)
INITIAL SETTING
SET COMMAND 1
SET COMMAND 4 (88H ~ 8FH : Display ON)
MAIN PROGRAM
SET COMMAND 2 (READ KEY & WRITE DATA INCLUDED) MAIN LOOP SET COMMAND 3
SET COMMAND 1
SET COMMAND 4
E ND
Notes: 1. Command 1: Display Mode Commands 2. Command 2: Data Setting Commands 3. Command 3: Address Setting Commands 4. Command 4: Display Control Commands 5. When IC power is applied for the first time, the contents of the Display RAM are not defined; thus, it is strongly suggested that the contents of the Display RAM must be cleared during the initial setting.
PT6955 V1.5 - 12 June, 2005
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LED Driver IC
PT6955
SOP 24L (300MIL) THERMAL PERFORMANCE IN STILL AIR
JUNCTION TEMPERATURE: 100
PT6955 V1.5
- 13 -
June, 2005
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LED Driver IC
PT6955
ABSOLUTE MAXIMUM RATINGS
(Unless otherwise stated, Ta=25 , GND=0V) Parameter Supply Voltage Logic Input Voltage Driver Output Current/Pin Maximum Driver Output Current/Total Operating Temperature Storage Temperature
Symbol VDD VI IOLGR IOHSG ITOTAL Topr Tstg
Rating -0.5 to +7.0 -0.5 to VDD+0.5 +250 -50 400 -40 ~ +85 -65 ~ +150
Units V V mA mA mA
RECOMMANDED OPERATING RANGE
(Unless otherwise stated, Topr=-40 to +85 , GND=0V) Parameter Symbol Min. Typ. Max. Logic Supply Voltage VDD 4.5 5 5.5 Dynamic Current (see note) IDDdyn 5 High-Level Input Voltage VIH 0.8VDD VDD Low-Level Input Voltage VIL 0 0.3VDD Note: Test Condition: Set Display Control Commands = 80H (Display Turn Off State)
Unit V mA V V
PT6955 V1.5
- 14 -
June, 2005
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LED Driver IC
PT6955
ELECTRICAL CHARACTERISTICS
(Unless otherwise stated, VDD=5V, GND=0V, Ta=25 ) Parameter Symbol Test Condition VO=VDD-1V IOHSG(1) SG1 to SG9, SG10/GR7 to SG12/GR5 High-Level Output Current VO=VDD-2V IOHSG(2) SG1 to SG9, SG10/GR7 to SG12/GR5 VO=0.3V Low-Level Output Current IOLGR GR1 to GR4, SG10/GR7 to SG12/GR5 VO=VDD-1V Segment High-Level ITOLSG SG1 to SG9, Output Current Tolerance SG10/GR7 to SG12/GR5 High-Level Input Voltage VIH Low-Level Input Voltage VIL Oscillation Frequency fosc R=51K
Min.
-10 -20 100 0.8VDD 350
Typ.
-14 -25 140 500
Max.
-30 -50 5 0.3VDD 650
Unit
mA mA mA % V V KHz
PT6955 V1.5
- 15 -
June, 2005
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LED Driver IC
PT6955
APPLICATION CIRCUIT
Notes: 1. The capacitor (0.1F) connected between the GND and VDD Pins must be located as near as possible to the PT6955 chip. 2. The PT6955 power supply is separate from the application system power supply.
COMMON CATHODE TYPE LED PANEL
SE G1 SE G2 SE G3 SE G4 SE G5 SE G6 SE G7 SE G8 a b c d e f g h e d f g c a b COM/DIG ITAL (GRID)
oh
PT6955 V1.5
- 16 -
June, 2005
Tel: 886-2-66296288 Fax: 886-2-29174598 URL: http://www.princeton.com.tw
LED Driver IC
PT6955
ORDER INFORMATION
Valid Part Number PT6955 Package Type 24pins, SOP, 300mil Top Code PT6955
PT6955 V1.5
- 17 -
June, 2005
Tel: 886-2-66296288 Fax: 886-2-29174598 URL: http://www.princeton.com.tw
LED Driver IC
PT6955
PACKAGE INFORMATION
24 PINS, SOP, 300 MIL
Symbols A A1 B C D E e H h L
Min. 2.35 0.10 0.33 0.23 15.20 7.40
10.00 0.25 0.40 0
Nom.
Max. 2.65 0.30 0.51 0.32 15.60 7.60
10.65 0.75 1.27 8
1.27 bsc.
PT6955 V1.5
- 18 -
June, 2005
Tel: 886-2-66296288 Fax: 886-2-29174598 URL: http://www.princeton.com.tw
LED Driver IC
PT6955
Notes: 1. Dimensioning and tolerancing per ANSI Y 14.5-1982. 2. Dimension "D" does not include mold flash, protrusions or gate burrs. Mold Flash, protrusion or gate burrs shall not exceed 0.15mm (0.006 in)per side. 3. Dimension "E" does not include interlead flash protrusions. Interlead flash or protrusions shall not exceed 0.25 mm (0.010 in) per side. 4. The chamfer on the body is optional. It is not present, a visual index feature must be located within the crosshatched area. 5. "L" is the length of the terminal for soldering to a substrate. 6. "N" is the number of terminal position. (N=24) 7. The lead width "B" as measured 0.36 mm (0.014 in) or greater above the seating plane, shall not exceed a maximum value of 0.61mm (0.24 in). 8. Controlling dimension: MILLIMETER. 9. Refer to JEDEC MS-013, Variation AD. JEDEC is the trademark of JEDEC SOLID STATE TECHNOLOGY ASSOCIATION.
PT6955 V1.5
- 19 -
June, 2005

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