COP413C Datasheet, PDF (9/16 Pages) National Semiconductor (TI) – Single-Chip CMOS Microcontrollers

Functional Description (Continued)
HALT MODE
The COP413C is a fully static circuit therefore the user may
stop the system oscillator at any time to halt the chip The
chip may be halted by the HALT instruction Once in the
HALT mode the internal circuitry does not receive any clock
signal and is therefore frozen in the exact state it was in
when halted All information is retained until continuing The
HALT mode is the minimum power dissipation state
The HALT mode may be entered into by program control
(HALT instruction) which forces CKO to a logic ‘‘1’’ state
The circuit can be awakened only by the RESET function
POWER DISSIPATION
The lowest power drain is when the clock is stopped As the
frequency increases so does current Current is also lower
at lower operating voltages Therefore to minimize power
consumption the user should run at the lowest speed and
voltage that his application will allow The user should take
care that all pins swing to full supply levels to ensure that
outputs are not loaded down and that inputs are not at
some intermediate level which may draw current Any input
with a slow rise or fall time will draw additional current A
crystal- or resonator-generated clock will draw more than a
square-wave input An RC oscillator will draw even more
current since the input is a slow rising signal
If using an external squarewave oscillator the following
equation can be used to calculate the COP413C current
drain
Ic e Iq a (V c 20 c Fi) a (V c 1280 c Fl Dv)
where Ic e chip current drain in microamps
Iq e quiescent leakage current (from curve)
Fl e CKI frequency in megahertz
V e chip V_CC in volts
Dv e divide by option selected
For example at 5V V_CC and 400 kHz (divide by 8)
Ic e 30 a (5 c 20 c 0 4) a (5 c 1280 c 0 4 8)
Ic e 30 a 40 a 320 e 390 mA
OSCILLATOR OPTIONS
There are two options available that define the use of CKI
and CKO
a Cyrstal-Controlled Oscillator CKI and CKO are connect-
ed to an external crystal The instruction cycle time
equals the crystal frequency divided by 8
b RC-Controlled Oscillator CKI is configured as a single
pin RC-controlled Schmitt trigger oscillator The instruc-
tion cycle equals the oscillation frequency divided by 4
CKO is NC
The RC oscillator is not recommended in systems that re-
quire accurate timing or low current The RC oscillator
draws more current than an external oscillator (typically an
additional 100 mA at 5V) However when the part halts it
stops with CKI high and the halt current is at the minimum
TL DD 8537 – 6
FIGURE 6 COP413C Oscillator
Crystal
Value
32 kHz
455 kHz
2 000 MHz
Crystal or Resonator
R1
220k
5k
2k
Component Value
R2
C1 pF
C2 pF
20M
30
5 – 36
10M
80
40
1M
30
6 – 36
RC-Controlled
Oscillator
R
C
Cycle
Time
15k
82 pF
4–9 ms
30k
82 pF
8 – 16 ms
47k
100 pF
16 – 32 ms
56k
100 pF
16 – 32 ms
Note 15k ^s R ^s 150k
50 pF ^s C ^s 150 pF
V_CC
t _{4 5V COP413CH Only}
t _{4 5V COP413CH Only}
3 0 to 4 5V COP413C Only
t _{4 5V}
9