STCD2400 Datasheet, PDF (13/39 Pages) STMicroelectronics – Multichannel clock distribution circuit

STCD22x0, STCD23x0, STCD24x0
Device operation
Table 6.
Truth table for enable signals (EN1-4), master clock input (MCLK) and
output clocks (CLK1-4)
EN1 EN2 EN3 EN4 MCLK
CLK1
CLK2
CLK3
CLK4
0
0
0
0
X
NO CLOCK NO CLOCK NO CLOCK NO CLOCK
1
0
0
0 CLOCK CLOCK NO CLOCK NO CLOCK NO CLOCK
1
1
0
0 CLOCK CLOCK
CLOCK NO CLOCK NO CLOCK
-
-
-
-
-
-
-
-
-
1
1
1
1 CLOCK CLOCK
CLOCK
CLOCK
CLOCK
Note:
"0" means logic low and "1" means logic high. When there is NO CLOCK output, the CLKx
pin stays at logic low. "X" means don't care. This is an active high truth table. Refer to
Section 3.2: Enable polarity for the detailed enable active high/low options.
3.2
Enable polarity
In different applications, the user may have different requirements for enable active high or
active low (enable polarities). MC_REQ is active low. STMicroelectronics offers different
solutions for the user to obtain different enable polarities.
In the STCD22x0 and STCD24x0, the user can configure the enable active high or active
low on the PC board by connecting OPT1 and OPT2 to either V_CC or ground. Refer to
Table 7 for detailed information.
In the STCD23x0, STMicroelectronics offers 4 enable polarity options by factory
programming for the user. Refer to Table 7 for detailed information.
The user should note that OPT1 and OPT2 must be connected to either V_CC or GND on the
PC board and floating on these pins could cause problems.
Table 7. STCD22x0, STCD23x0 and STCD24x0 and enable polarity options
Part number
Enable polarities (OPT1, OPT2)
Enable polarity
program method
STCD2200
OPT1 connected to V_CC, EN1 active high
OPT1 connected to GND, EN1 active low
OPT2 controls EN2
STCD2400
STCD2410
OPT1 connected to V_CC, EN1 and EN2 active high
OPT1 connected to GND, EN1 and EN2 active low
OPT2 controls EN3 and EN4
OPT1 connected to V_CC, EN1 active high
OPT1 connected to GND, EN1 active low
OPT2 controls EN2, EN3, and EN4
User program
STCD2300
STCD2310
STCD2320
STCD2330
EN1, EN2 and EN3 all active low
EN1, EN2 active low, and EN3 active high
EN1, EN2 active high and EN3 active low
EN1, EN2 and EN3 all active high
Factory program
Doc ID 15400 Rev 2
13/39