4 digit 7 segment LED displays with Cascadable Serial driver ______________________________________________________ B14SC04 B20SC04 B25SC04 B38SC04 General Description The B14SCM04, B20SC04, B25SC04 and B38SC04 displays are 4 digit seven segment LED displays combined with an 8 digit, multiplexed drive, integrated circuit with a cascadable serial interface. Four digits are mounted with the driver on to the PCB which also has connections for the BM multiplexed display family allowing expansion to 8 digits. The devices are available in high efficiency red, green and yellow colour variants. Each of the standard displays has a right hand decimal point in each digit. LED sizes include 14mm (0.56inch), 20mm (0.8inch) 25mm (1inch) and 38mm (1.5inch) display areas. The on board driver chip has a serial input format that features serial data, clock and chip enable. A single 5 volt supply is required. The serial bus signals interface is HCMOS levels and the format is compatible with SPI, QSPI and MICROWIRE. It features slew rate limiting for reduced EMI. Included on chip is a BCD code B decoder and digit ram. An undedecoded mode is also available. The chip can be programmed to display from 1 to 8 digits using the scan limit register. Only one external resistor is required to set the maximum brightness that can then be digitally dimmed in 16 levels. A test mode forces all LED's on. Low power shutdown reduces current to 150uA. Configuration Dimensions Dim (mm) A B14 B20 B25 B38 58.5 75.0 97.0 121.0 B 2.54 2.54 2.54 2.54 C 14.0 20.0 25.0 38.0 D 37.0 38.0 44.0 54.0 E 51.5 68.5 90.0 115.5 Depth 16.0 18.0 18.0 18.0 Pinout 1 +5V +5V 2 3 5 CS CLK DIN DOUT 4 6 7 0V 0V 8 9 SEGA SEGB 10 11 SEGC SEGD 12 13 15 17 19 SEGE SEGG DIG1 DIG3 SEGF SEGDP DIG2 DIG4 14 16 18 20 Nexus Machines Ltd reserves the right to alter or withdraw the product specification and characteristics without prior notice at any time in line with product development. Nexus Machines Ltd sole and exclusive warranty is that stated in the warranty article of the conditions of sale. Although every effort is made to ensure this data is accurate no liability is accepted for errors or omissions that may affect the end product. Week0802 -1- Electrical Characteristics Parameter Supply voltage Shutdown supply current Power supply current Display scan rate Input voltage logic 0 (VL) Input voltage logic 1 (VH) Segment drive current(seg off) Segment drive current(seg on) Segment matching Output sink current (digit off) Output sink current (digit on) Clock High time Clock Low time Clock period CS fall to SCLK rise setup Clk rise to CS rise hold time Din setup time Din hold time Output data prop delay Load rising edge to next clk rising edge Minimum CS or load pulse high time Data input to seg delay Data input hold time Brightness setting resistor Operating temperature Min 4.0 500 -0.3 3.5 Typ 5.0 330 800 Max 5.5 150 1300 0.8 Units V uA mA Hz V V 1 uA -45 50 mA % uA mA ns ns ns ns ns ns ns ns ns 50 ns 2.5 300 ns ns -30 -40 3 10 320 50 50 100 25 0 25 0 25 9.53 0 70 k ohms deg C Conditions All leds off All segs on 8 digits scanned Vcc=5.0 volts Vcc=5.0 volts Vdig=10 volts Vout=0.65 tr = tf = 20ns Vdd=5V +/- 10% Vdd=5V 4 LED's on Nexus Machines Ltd reserves the right to alter or withdraw the product specification and characteristics without prior notice at any time in line with product development. Nexus Machines Ltd sole and exclusive warranty is that stated in the warranty article of the conditions of sale. Although every effort is made to ensure this data is accurate no liability is accepted for errors or omissions that may affect the end product. Week0802 -2- Pin Functions +5v Pin 1,2 +5 volts power supply to LED Chip enable Pin 3 Chip select - this pin must be low for a data transfer to occur. he last 16 bits of serial data are latched on CS rising edge. Data input Pin 4 Serial data input -data is loaded into the internal 16 bit register on the clocks rising edge. Clock Pin 5 Clock line - On clocks rising edge data is shifted into the internal shift register. On clocks falling edge data is shifted out of Dout. Data output Pin 6 Serial data output -the data into DIN is valid at DOUT 16.5 clock cycles later. This pin is used to daisy chain devices 0 Volts Pin 7,8 The chip and LED's 0 volts line. Segments A,B,C,D,E,F,G and DP Pins 9,10,11,12,13,14,15,16 Seven Segment drives and decimal point Drive that source current to the display Digit 4,5,6,7 Pin 17,18,19,20 Digit lines 4 through 7 drive line that sinks current from the common cathode LED. These can be used to drive an external 4 digit 7 segment LED display(BM series). Digit lines 0 to 3 are connected to the "internal" display. Digit 0 is the LSB on the right hand side. Serial Data Format (16 bits) 15 14 13 12 11 10 X X X X A3 A2 9 A1 8 A0 7 D7 6 D6 5 D5 4 D4 3 D3 2 D2 1 D1 0 D0 Nexus Machines Ltd reserves the right to alter or withdraw the product specification and characteristics without prior notice at any time in line with product development. Nexus Machines Ltd sole and exclusive warranty is that stated in the warranty article of the conditions of sale. Although every effort is made to ensure this data is accurate no liability is accepted for errors or omissions that may affect the end product. Week0802 -3- Register Address Map Register D15-D12 No operation X Digit 0 X Digit 1 X Digit 2 X Digit 3 X Digit 4 X Digit 5 X Digit 6 X Digit 7 X Decode mode X Intensity X Scan limit X Shutdown X Display test X A3 0 0 0 0 0 0 0 0 1 1 1 1 1 1 A2 0 0 0 0 1 1 1 1 0 0 0 0 1 1 A1 0 0 1 1 0 0 1 1 0 0 1 1 0 1 A0 0 1 0 1 0 1 0 1 0 1 0 1 0 1 Hex code X0 X1 X2 X3 X4 X5 X6 X7 X8 X9 XA XB XC XF Display command Register Functions Shutdown register Format (address Xch) Mode Address D7 D6 D5 Shutdown XCh X X X Mode Normal XCh X X X Operation D4 X D3 X D2 X D1 X D0 0 X X X X 1 Decode Mode Register: Setting this register sets BCD code (0-9,E,H,L,P and -) or no decode operation for each digit. Each bit in the register corresponds to one digit. A logic 1 selects Code B decoding whereas a logic 0 enables non decode mode. In decode mode bits 0-3 correspond to the BCD data for the digit and bit D7 is the decimal point. In non decode mode data bits 0 to 7 correspond to the segment lines as outlines in the table below. Decode Mode register examples Decode Mode D7 No decode for digits 7-0 Code B decode for digit 0 and no decode for digits 7-1 Code B decode for digits 3-0 and no decode for digits 7-4 Code B decode for digits 7-0 D6 D5 D4 D3 D2 D1 D0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 1 Hex code 00 01 0 0 0 0 1 1 1 1 0Fh 1 1 1 1 1 1 1 1 FFh Nexus Machines Ltd reserves the right to alter or withdraw the product specification and characteristics without prior notice at any time in line with product development. Nexus Machines Ltd sole and exclusive warranty is that stated in the warranty article of the conditions of sale. Although every effort is made to ensure this data is accurate no liability is accepted for errors or omissions that may affect the end product. Week0802 -4- Decode Mode 7 Seg D7 character 0 DP 0n =1 1 DP 0n =1 2 DP 0n =1 3 DP 0n =1 4 DP 0n =1 5 DP 0n =1 6 DP 0n =1 7 DP 0n =1 8 DP 0n =1 9 DP 0n =1 DP 0n =1 E DP 0n =1 H DP 0n =1 L DP 0n =1 P DP 0n =1 Blank DP 0n =1 D6-D4 D3 D2 D1 D0 Dont care Dont care Dont care Dont care Dont care Dont care Dont care Dont care Dont care Dont care Dont care Dont care Dont care Dont care Dont care Dont care 0 0 0 0 0 0 0 0 1 1 1 1 1 1 1 1 0 0 0 0 1 1 1 1 0 0 0 0 1 1 1 1 0 0 1 1 0 0 1 1 0 0 1 1 0 0 1 1 0 1 0 1 0 1 0 1 0 1 0 1 0 1 0 1 D6 A D5 B Non Decode Mode Segment line D7 DP D4 C D3 D D2 E D1 F D0 G The LED current is set to a maximum value via an on board resistor. This provides the maximum level of brightness. The LED display controller also features a facility to Digitally set the display brigtness from the host microcontroller. This control allows the on board pulse width modulator to control the segment current and thus the brightness. Intensity Register Format Duty Cycle D7-D4 1/32 (min) Dont care 3/32 Dont care 5/32 Dont care 7/32 Dont care 9/32 Dont care 11/32 Dont care 13/32 Dont care 15/32 Dont care 17/32 Dont care 19/32 Dont care 21/32 Dont care 23/32 Dont care 25/32 Dont care 27/32 Dont care 29/32 Dont care 31/32 Dont care D3 0 0 0 0 0 0 0 0 1 1 1 1 1 1 1 1 D2 0 0 0 0 1 1 1 1 0 0 0 0 1 1 1 1 D1 0 0 1 1 0 0 1 1 0 0 1 1 0 0 1 1 D0 0 1 0 1 0 1 0 1 0 1 0 1 0 1 0 1 Hex code X0h X1h X2h X3h X4h X5h X6h X7h X8h X9h XAh XBh XCh XDh XEh XFh Nexus Machines Ltd reserves the right to alter or withdraw the product specification and characteristics without prior notice at any time in line with product development. Nexus Machines Ltd sole and exclusive warranty is that stated in the warranty article of the conditions of sale. Although every effort is made to ensure this data is accurate no liability is accepted for errors or omissions that may affect the end product. Week0802 -5- The display also features a scan limit register that sets how many digits are displayed from 1 to 8.These are displayed in a multiplexed manner with a typical display scan rate of 800Hz. Since the number of digits displayed affects the overall display intensity the scan limit registers should not be used to provide leading zero suppression. WARNING: DO NOT select less than 3 scanned digits (there are 4 leds on the display so it should be set to 4) otherwise excessive power dissipation will occur in the driver chip. Scan Limit Register format Scan Limit D7-D3 D2 D1 D0 Digit 0 Digit 0,1 Digit 0,1,2 Digit 0,1,2,3 Digit 0,1,2,3,4 Digit 0,1,2,3,4,5 Digit 0,1,2,3,4,5,6 Digit 0,1,2,3,4,5,6,7 0 0 0 0 1 1 1 1 0 0 1 1 0 0 1 1 0 1 0 1 0 1 0 1 Dont care Dont care Dont care Dont care Dont care Dont care Dont care Dont care Hex code X0h X1h X2h X3h X4h X5h X6h X7h Nexus Machines Ltd reserves the right to alter or withdraw the product specification and characteristics without prior notice at any time in line with product development. Nexus Machines Ltd sole and exclusive warranty is that stated in the warranty article of the conditions of sale. Although every effort is made to ensure this data is accurate no liability is accepted for errors or omissions that may affect the end product. Week0802 -6- LED display characteristics The Led display provides excellent output brightness verses forward current with intensity matching of better than 10% and a long operating life with minimal display degradation. The LED's on the driver PCB are termed "Internal" LED's, whilst those that can be attached to the driver chip via a cable (not longer than 10 inches) are termed external. Note that additional LED displays may require greater supply decoupling. It is recommended that 10uf of capacitance be added for every additional LED digit. A 10 volt electrolytic is suitable. EMC: The displays are designed with slew limited drivers to ensure minimal EMC emmissions. However the cable that is wired to the display is a large source of unwanted emissions. Care should be taken to ensure minimal cable lengths are used where ever possible and a ferrite ring should be added to the cable to provide additional attenuation. The LED's draw quite a high instantaneous current and the power supply and its wiring should be designed to carry the current whilst providing a low impedance path. Additional capacitance may be required at the display. The end product must be complient with the relevant criteria and the user should check that the display is connected such that it is so. Display LED format Digit 7 Digit 6 Ext LHS Ext LHM Digit5 Ext RHM Digit 4 Ext RHS LED brightness Min/Typ (mCd) Color 14mm 20mm Green 0.9 / 2.4 1.0 / 2.55 HE Red 0.9 / 2.4 1.0 / 2.55 Yellow 0.9 / 2.4 1.0 / 2.55 Digit 3 Int LHS 25mm 1.3 / 3.3 1.4 / 3.6 1.3 / 3.2 Digit 2 Int LHM Digit 1 Int RHM Digit 0 Int RHS 38mm 1.3 / 3.6 1.4 / 3.6 1.3 / 3.2 Cascading displays: The displays are cascadable by connecting the Dout pin from the first display to the Din pin on the next display in line. The other signals (chip enable and clock) are common to all displays. The number of data bits remains the same for each display hence if 4 displays are cascaded then 64 bits are required to alter the displayed value ON ANY DISPLAY. The command set allows for a NO OPERATION which leaves the addressed display with the previous register values. MAXIMUM RATINGS: THE USER IS DIRECTED TOWARDS THE MAXIMUM VALUES OUTLINED IN THE ELECTRICAL CHARACTERISTICS. OPERATION OUTSIDE OF THESE LIMITS MAY AFFECT PERMANENT DAMAGE TO THE LED DISPLAY OR THE DRIVER CHIP. Additional Information: The user is directed towards the Maxim Integrated Products data sheet for the MAX7219/MAX7221 for information regarding the serial interface and further display driver commands. All Trade marks acknowledged. Nexus Machines Ltd reserves the right to alter or withdraw the product specification and characteristics without prior notice at any time in line with product development. Nexus Machines Ltd sole and exclusive warranty is that stated in the warranty article of the conditions of sale. Although every effort is made to ensure this data is accurate no liability is accepted for errors or omissions that may affect the end product. Week0802 -7- Typical Applications Simple 4 digit display to microcontroller interface. Cascading LED displays Nexus Machines Ltd reserves the right to alter or withdraw the product specification and characteristics without prior notice at any time in line with product development. Nexus Machines Ltd sole and exclusive warranty is that stated in the warranty article of the conditions of sale. Although every effort is made to ensure this data is accurate no liability is accepted for errors or omissions that may affect the end product. Week0802 -8- Data prepared by : Nexus Machines Ltd White Swan House 60 High Street Godstone Surrey RH9 8LW Email : Web site : Technical support: sales@nexusmachines.com www.nexusmachines.com 0906 558 1010 Please note that the technical support line is charged at a rate of 1 per minute. Nexus Machines Ltd reserves the right to alter or withdraw the product specification and characteristics without prior notice at any time in line with product development. Nexus Machines Ltd sole and exclusive warranty is that stated in the warranty article of the conditions of sale. Although every effort is made to ensure this data is accurate no liability is accepted for errors or omissions that may affect the end product. Week0802 -9-