LS7030_03 Datasheet, PDF (1/4 Pages) LSI Computer Systems – 8 DECADE MULTIPLEXED COUNTER

LSI/CSI
LS7030
U_{® L}
LSI Computer Systems, Inc. 1235 Walt Whitman Road, Melville, NY 11747 [phone] FAX [phone]
A3800
8 DECADE MULTIPLEXED COUNTER
January 2003
FEATURES:
• DC to 7.5 MHz Count Frequency
• Multiplexed BCD and 7 Segment Outputs
• DC to 500 kHz Scan Frequency
• +4.75V to +15V Operation (Vss - Vdd)
CONNECTION DIAGRAM - TOP VIEW
SCAN RESET INPUT ¹
MSD STROBE 8 2
40 OSC. INPUT
39 SCAN INPUT
• Compatible with CMOS Logic
• High Input Noise Immunity
• Counter Output Latches
• Leading Zero Blanking
• Low Power Dissipation
• All inputs protected
• 40 Pin DIP - See Figure 1
DIGIT
STROBE
OUTPUTS
STROBE 7 ₃
STROBE 6 4
STROBE 5 5
STROBE 4 6
STROBE 3 7
STROBE 2 8
38 LAMP TEST INPUT
37 a
36 b
35 N.C.
34 ^c
SEGMENT
OUTPUTS
33 d
DESCRIPTION: (See Block Diagram, Figure 4.)
The LS7030 is a MOS, 8 decade up counter. The circuit includes
latches, multiplexer, leading zero blanking and 7 segment data
outputs.
LSD STROBE 1 9
DECIMAL POINT INPUT ₁₀
BLANK OUTPUT ₁₁
OVERFLOW OUTPUT 12
LS7030
32 COUNT INPUT
31 e
30 f
29 ^g
SEGMENT
OUTPUTS
8 DECADE UP COUNTER
The eight decade ripple through counter increments on the neg-
ative edge of the input count pulse. Maximum ripple time is 12µs
(99999999 to 00000000). Maximum count frequency is 7.5MHz.
RESET
All decades are reset to zero when Reset input is brought low for
a minimum of 4µs. The Overflow flip-flop is reset at the same
time. Reset must be high for a minimum of 1µs before next valid
count can be recorded.
OVERFLOW INPUT 13
DECADE 6 OUTPUT, D8 ₁₄
DECADE 7 OUTPUT, D7 15
DECADE 6 OUTPUT, D6 ₁₆
BCD
DATA
OUTPUTS
B8 ₁₇
B4 18
B2 19
B1 ²⁰
28 TEST COUNT INPUT, DIGITS 3 - 8
27 V SS
26 V GG
25 N.C.
24 _N.C.
23 V DD
22 RESET COUNTER INPUT
21 LOAD LATCH INPUT
LATCHES
Contents of counter are transferred to latches when LOAD signal
is brought low for a minimum of 4µs and kept low until a minimum
of 12µs has elapsed from previous negative edge of count pulse
(ripple time). Storage of valid data occurs when LOAD signal is
high for a minimum of 1µs before next negative edge of count
pulse or reset. Data is transferred for Overflow flip-flop to Over-
flow latch at the same time.
SCAN OSCILLATOR AND COUNTER
The scan counter is driven by an internal oscillator whose fre-
quency is determined by a capacitor connected between Os-
cillator input and Scan input. An external scan clock applied to
Scan input can also drive the scan counter. Scan counter ad-
vances on negative edge of scan clock.
The counter scans from MSD to LSD. When Scan Reset input is
brought high the scan counter is forced to MSD state. Internal
synchonization guarantees proper scanning no matter when Scan
Reset is brought low relative to scan clock. Maximum scan
frequency is 500kHz.
DECIMAL POINT
A high at the Decimal Point input resets the Blanking flip-flop
causing the display to unblank. Decimal Point should be brought
high at start of digit time which has active Decimal Point.
7030 - 012703 - 1
FIGURE 1
DIGIT STROBES
Timing of Digit Strobes is arranged such that both edges of strobe
are guardbanded by a minimum 400ns within valid BCD data when
scan frequency is 100kHz or less. The guardband is a minimum of
200ns at 250kHz scan frequency. At 500kHz only negative edge of
Strobe is guaranteed to be within valid BCD data by a minimum
200ns.
OVERFLOW
The Overflow flip-flop sets on the first negative transition of the Over-
flow Input and remains set until Reset is brought low. Data is trans-
ferred from Overflow flip-flop to Overflow Latch when Load is brought
low. A high at the Overflow Latch causes display to unblank. Over-
flow Output is output of Overflow Latch. MSB outputs of Decades
6, 7, 8 are available for use as Overflow Input.
BLANKING
Leading zero blanking is employed. At start of each MSD to LSD
scan, display is blanked until a nonzero digit or active decimal point is
encountered. Displaly unblanks during LSD time and for a whole
scan when Overflow output is high. When Scan Reset is applied, dis-
play blanks to prevent display damage.
Blanking information is available at Blank output and is incorporated
into 7 segment information.