Revised March 2000 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 incandescent 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. Ordering Code: Order Number DM9370 Package Number N16E Package Description 16-Lead Plastic Dual-In-Line Package (PDIP), JEDEC MS-001, 0.300 Wide Connection Diagram Logic Symbol VCC = Pin 16 GND = Pin 8 Pin Descriptions Pin Names Description A0–A3 Address Inputs LE Latch Enable Input (Active LOW) RBI Ripple Blanking Input (Active LOW) RBO Ripple Blanking as Output (Active LOW) a–g Segment Outputs (Active LOW) as Input (Active LOW) © 2000 Fairchild Semiconductor Corporation DS009797 www.fairchildsemi.com DM9370 7-Segment Decoder/Driver/Latch with Open-Collector Outputs October 1988 DM9370 Truth Table *The RBI will blank the display only if binary zero is stored in the latches. **RBO used as an input overdrives all other input conditions. H = HIGH Voltage Level L = LOW Voltage Level X = Immaterial Functional Description cuits—traditionally found in incandescent multiplexed display systems are eliminated. It also allows low strobing rates to be used without display flicker. The DM9370 has active LOW outputs capable of sinking in excess of 25 mA which allows it to drive a wide variety of 7segment 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 device accepts a 4-bit binary code and produces output drive to the appropriate segments of the 7-segment display. It has a hexadecimal decode format which produces numeric codes “0” through “9” and alpha codes “A” through “F” using upper and lower case fonts. Another DM9370 feature is the reduced loading on the data inputs when the Latch Enable is HIGH (only 10 µA typ). This allows many DM9370s to be driven from a MOS device in multiplex mode without the need for drivers on the data lines. The DM9370 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 normal writing practice. In an 8-digit mixed integer fraction decimal representation, using the automatic blanking capability, 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 significant 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 decoder stage should be left open. A similar procedure for the fractional part of a display will provide automatic suppression of trailing-edge zeroes. The RBO terminal of the decoder can be OR-tied with a modulating signal via an isolating buffer to achieve pulse duration intensity modulation. A suitable signal can be generated for this purpose by forming a variable frequency multivibrator with a cross coupled pair of TTL or DTL gates. 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 DM9370 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 the system clock or providing intermediate 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 circuits—seven diodes per display, strobe drivers, a separate display voltage source, and clock failure detect cir- www.fairchildsemi.com 2 DM9370 Numerical Designation Logic Diagram 3 www.fairchildsemi.com DM9370 Absolute Maximum Ratings(Note 1) Supply Voltage Note 1: The “Absolute Maximum Ratings” are those values beyond which the safety of the device cannot be guaranteed. The device should not be operated at these limits. The parametric values defined in the Electrical Characteristics tables are not guaranteed at the absolute maximum ratings. The “Recommended Operating Conditions” table will define the conditions for actual device operation. 7V Input Voltage 5.5V 0°C to +70°C Operating Free Air Temperature Range −65°C to +150°C Storage Temperature Range Recommended Operating Conditions Symbol Parameter Min Nom Max Units 4.75 5 5.25 V LOW Level Input Voltage 0.8 V VCC Supply Voltage VIH HIGH Level Input Voltage VIL 2 V IOH HIGH Level Output Current −80 µA IOL LOW Level Output Current 3.2 mA TA Free Air Operating Temperature 70 °C tS (H) Setup Time HIGH or LOW 30 tS (L) An to LE 20 0 tH (H) Hold Time HIGH or LOW 0 tH (L) An to LE 0 tW (L) LE Pulse Width LOW 45 ns ns ns Electrical Characteristics Over recommended operating free air temperature range (unless otherwise noted) Symbol Parameter Conditions VI Input Clamp Voltage VCC = Min, II = −12 mA VOH HIGH Level VCC = Min, IOH = Max VOL Output Voltage VIL = Max LOW Level VCC = Min, IOL = Max Min 2.4 Typ (Note 2) Max Units −1.5 V 3.4 V 0.2 0.4 V 1 mA −1.6 mA −70 mA Output Voltage VIH = Min II Input Current @ Max Input Voltage VCC = Max, VI = 5.5V IIL LOW Level Input Current VCC = Max, VI = 0.4V IOS Short Circuit Output Current VCC = Max (Note 3) −20 VOH Output HIGH Voltage RBO VCC = Min, IOH −80 µA 2.4 VOL Output LOW Voltage RBO IOL = 3.2 mA a–g IOL = 25 mA 0.4 250 µA VCC = Max 105 µA A1, A2, A 3, LE = GND 105 IOH Output HIGH Current, a–g ICC Power Supply Current V VCC = Min 0.4 V VCC = Max, Outputs OPEN mA A0, A1, A 2, LE = GND 94 VCC = Max, Outputs OPEN Note 2: All typicals are at VCC = 5V, TA = 25°C. Note 3: Not more than one output should be shorted at a time. Switching Characteristics VCC = +5.0V, TA = +25°C Symbol CL = 15 PF, RL = 500Ω Parameter Min Max tPLH Propagation Delay 75 tPHL An to a–g 50 tPLH Propagation Delay 90 tPHL LE to a–g 70 www.fairchildsemi.com 4 Units ns ns DM9370 7-Segment Decoder/Driver/Latch with Open-Collector Outputs Physical Dimensions inches (millimeters) unless otherwise noted 16-Lead Plastic Dual-In-Line Package (PDIP), JEDEC MS-001, 0.300 Wide Package Number N16E Fairchild does not assume any responsibility for use of any circuitry described, no circuit patent licenses are implied and Fairchild reserves the right at any time without notice to change said circuitry and specifications. LIFE SUPPORT POLICY FAIRCHILD’S PRODUCTS ARE NOT AUTHORIZED FOR USE AS CRITICAL COMPONENTS IN LIFE SUPPORT DEVICES OR SYSTEMS WITHOUT THE EXPRESS WRITTEN APPROVAL OF THE PRESIDENT OF FAIRCHILD SEMICONDUCTOR CORPORATION. As used herein: 2. A critical component in any component of a life support device or system whose failure to perform can be reasonably expected to cause the failure of the life support device or system, or to affect its safety or effectiveness. 1. Life support devices or systems are devices or systems which, (a) are intended for surgical implant into the body, or (b) support or sustain life, and (c) whose failure to perform when properly used in accordance with instructions for use provided in the labeling, can be reasonably expected to result in a significant injury to the user. www.fairchildsemi.com 5 www.fairchildsemi.com