9370 National Semiconductor DM9370 7-Segment Decoder/Driver/Latch with Open-Collector Outputs General Description The DM9370 is a 7-segment decoder driver incorporating input latches and output circuits to directly drive incandes- cent displays. It can also be used to drive common anode LED displays in either a multiplexed mode or directly with the aid of external current limiting resistors. Connection Diagram Dual-in-Line Package ar Aisi 16 Vee A242 15 i (e-43 th beg REO| 4 13;a REIT 5 12kb AS476 hc AO-17 1Ofd GND48 oe TL/F/9797-1 Order Number DM9370N See NS Package Number N16E Pin Names Description AO-A3 Address inputs LE Latch Enable Input (Active LOW) Rei Ripple Blanking Input (Active LOW) ABO Ripple Blanking as Output (Active LOW) as Input (Active LOW) a-g Segment Outputs (Active LOW) 4-322o oo Absolute Maximum Ratings (note) a If Military/Aerospace specified devices are required, Note: The Absolute Maximum Ratings are those values please contact the Natlonal Semiconductor Sales beyond which the safety of the davice cannot be guaran- Office/Distributors for availabillty and specifications. feed. The devic should not be operated at these limits. The Supply Voltage 7V parametric values defined in the Electrical Characteristics" input Voltage 5.5V lable are not guaranteed at the absojute maximum ratings. P . 9 ; . The Recommended Operating Conditions tabie will define Operating Free Air Temperature Range the conditions for actual device operation. Commercial OC to + 70C Storage Temperature Range 66C to + 150C Recommended Operating Conditions Symbol Parameter 0M9370 Units Min Nom Max Voo Supply Voltage 4.75 5 5.25 v ViH High Level Input Voltage 2 Vv VIL Low Levei Input Voltage 0.8 Vv lou High Level Output Current 80 pA lo. Low Level Output Current 3.2 mA Ta Free Air Operating Temperature 0 70 C ts (H) Setup Time HIGH or LOW 30 ns ts (L) Ay to LE 20 th (H) Hold Time HIGH or LOW 0 ns th() An to LE 0 ty (L) LE Pulse Width LOW 45 ns Electrical Characteristics Over recommended operating free air temperature range (unless otherwise noted) Symbol Parameter Conditions Min TyP Max Units (Note 1) Vv Input Clamp Voltage Voc = Min, || = 12mA -15 Vv Vou High Level Output Voc = Min, low = Max 24 44 Vv Voltage Vit = Max VoL Low Level Output Voc = Min, lo = Max 02 0.4 Vv Voltage Vin = Min h Input Current @ Max Voc = Max, V; = 5.5V 1 mA Input Voltage hh High Level Input Current Veo = Max, V| = 2.4V 40 BA lie Low Level Input Current Voc = Max, V; = 0.4V 1.6 mA los Short Circuit Voc = Max _ _ Output Current {Note 2) OM74 20 70 mA Vou Output HIGH Voltage RBO Voc = Min, lox 80 vA 2.4 Vv VoL Output LOW Voltage FBO lo. = 3.2 mA Veo = Min 0.4 Vv a-g lot = 25 mA 0.4 lou Output HIGH Current, a~g 250 pA loc Power Supply Current Voc = Max 105 pA Ay, Ag, As, LE = GND 105 Veco = Max, Outputs Open mA Ao, Ay, Ao, LE = GND 94 Vcc = Max, Outputs Open 4-3239370 Switching Characteristics Voc = +5.0V, Ta = +25C (See Section 1 for waveforms and load configurations) CL = 15 PF Symbol Parameter R, = 5000 Units Min Max teLy Propagation Delay 75 ns tPHL A, toa-g 50 tPLH Propagation Delay 90 ns teHL TE toa-g 70 Functional Description The '70 has active LOW outputs capable of sinking in ex- cess of 25 mA which allows it ta drive a wide variety of 7-segment incandescent displays directly. It may also be used to drive common anode LED displays, multiplexed or directly with the aid of suitable current limiting resistors. This devica accepts a 4-bit binary code and produces output drive to the appropriate segments of the 7-sagment display. It has a hexadecimal decode format which produces numer- ic codes 0 through '9 and alpha codes A through F using upper and lower case fonts. Latches on the four data inputs are controlled by an active LOW latch enable LE. When the LE is LOW, the state of the outputs is determined by the input data. When the LE goes HIGH, the last data present at the inputs is stored in the latches and the outputs remain stable. The LE pulse width necessary to accept and store data is typically 30 ns which allows data to be strobed into the 70 at normal TTL speeds. This feature means that data can be routed directly from high speed counters and frequency dividers into the display without slowing down tha system clock or providing interme- diate data storage. The latch/decoder combination is a simple system which drives incandescent displays with multiplexed data inputs from MOS time clocks, DVMs, calculator chips, etc. Data inputs are multiplexed while the displays are in static mode. This lowers component and insertion costs since several Ccircuitsseven diodes per display, strobe drivers, a sepa- Logic Symbol rate display voltage source, and clock failure detect cir- cuitstraditionally found in incandescent multiplexed dis- play systems are eliminated. It also allows low strobing rates to be used without display flicker. Another '70 feature is the reduced loading on the data in- puts when the Latch Enable is HIGH (only 10 A typ). This allows many 70s to be driven from a MOS device in multi- piex mode without the need for drivers on the data lines. The 70 also provides automatic blanking of the leading and/or trailing-edge zeroes in a multidigit decimal number, resulting in an easily readable decimal display conforming to nermat writing practice. In an 8-digit mixed integer fraction decimal representation, using the automatic blanking capa- bility, 0060.0300 would be displayed as 60.03. Leading- edge zero suppression is obtained by connecting the Ripple Blanking Output (RBO) of a decoder to the Ripple Blanking input (RBI of the next lower stage device. The most signifi- cant decoder stage should have the RBI input grounded: and since suppression of the least significant integer zero in a number is not usually desired, the RBI input of this decod- er stage should be left open. A similar procedure for the fractional part of a display will provide automatic suppres- sion of trailing-edge zeroes. The RBO terminal of the decod- er can be OR-tied with a modulating signal via an isolating buffer to achieve pulse duration intensity modulation. A suit- able signal can be generated for this purpose by ferming a variable frequency multivibrator with a cross coupled pair of TTL or DTL gates. AO Ai A2 A3 LE RBI RB0a be def g 413121110 9 1514 Voc = Pin 16 GND = Pin8 TL/F/9797-202E6 Truth Table INPUTS OUTPUTS BINARY STATE | CE RBI AB AZ AY AGL a boc ad 8 Fg RBG | DSPLAY -- |H * xX X X% & | ~~ sTABLE|H | STABLE o |b t tee eile # HK HH HI[L | BLANK o [LH LELLI]tt beeut ate a 1 Je x LLL HH &E L HHH daa 2 {LX LLHLUiJtt HeE LULA i 3 JL xX LLUH ASL bok tL WHA ULIH x 4 JL xX LueetH Len ae Liu 4 5 {LX LHL HEL HELUC LIH 5 6 |[L xX LHHLIL ALLL te LIH 7 |u X LHH HILL LuUdHH Hi 1 B [tL X HLLLILEULLL eta 5 9 [LX HLL HIE L LAH itl 5 to Ju X HL HLItL & LEuHL LU 5 woetbL x HL AW HIHHLLLEL tIH 2 LX HHL LI{t HHL LL HA r 13 L xX KH tt HIH LL Let H LI H TLAF/9797=4 14 |L X HH HLL HHLLULLH 15 }L X HHH HIL H HHAL L LIH : x |X x x xX X XTH H H HH H HL] BLANK TL/F/9797-6 *The ABi will blank the display only if binary zero is storad in the latches. **ABO used as an input overdrives all other input conditions. H = HIGH Voltage Level L = LOW Voltage Level X = (mmaterial Numerical Designation 6 4 5 10 14_*15 0 (SMS6 TGSAbL EF TL/F/9787-5 4-3259370 Logic Diagram few ene ew ewe ew @ = = sew ew ewe = oe = -_ = a AO 1 t | { 1 t e r I ! { - | { a ! { b + LtatcH 4 tp] 1-0F-15 LAY seowent PNY output PS bmw eee wenn dann eee ---- -4 | DECODER ENCODER DEVICES : 0 6 i A rt 1 9 Tt LATCH a2 | LATCH Ry AS >I LATCH E) _ r | * Le v _ RIPPLE __ Ri ORBLANKING (Q______ 34 CIRCUIT TL/F/9797-3 4-326