Samsung SC32442B54, User Manual

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K5D2G13ACM-D075
Revision 1.0
December 2006
42
MCP MEMORY
READY/BUSY
The device has a R/B output that provides a hardware method of indicating the completion of a page program, erase and random
read completion. The R/B pin is normally high but transitions to low after program or erase command is written to the command regis-
ter or random read is started after address loading. It returns to high when the internal controller has finished the operation. The pin is
an open-drain driver thereby allowing two or more R/B outputs to be Or-tied. Because pull-up resistor value is related to tr(R/B) and
current drain during busy(ibusy) , an appropriate value can be obtained with the following reference chart(Fig.20). Its value can be
determined by the following guidance.
V
CC
R/B
open drain output
Device
GND
Rp
Figure 19. Rp vs tr ,tf & Rp vs ibusy
ibusy
Busy
Ready Vcc
VOH
tf
tr
VOL
1.8V device - V
OL
: 0.1V, V
OH
: V
CC
-0.1V
C
L
tr,tf [s]
Ibusy [A]
Rp(ohm)
Ibusy
tr
@ Vcc = 1.8V, Ta = 25
°
C , C
L
= 30pF
1K 2K 3K
4K
100n
200n
300n 3m
2m
1m
30
tf
60
90
120
1.70
1.70
1.70
1.70
1.70
0.85
0.57
0.43
Rp(min, 1.8V part) =
V
CC
(Max.) - V
OL
(Max.)
I
OL
+
Σ
I
L
=
1.85V
3mA +
Σ
I
L
where I
L
is the sum of the input currents of all devices tied to the R/B pin.
Rp value guidance
Rp(max) is determined by maximum permissible limit of tr