D a t a S h e e t ( P r e l i m i n a r y )
4.2
Ready/Busy
The Ready/Busy output provides a method of indicating the completion of a page program, erase, copyback,
or read completion. The R/B# pin is normally high and goes to low when the device is busy (after a reset,
read, program, erase operation). 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 reference chart shown in Figure 4.1.
Figure 4.1 Ready/Busy Pin Electrical Application
Rp
3.3V device - VOL : 0.4V. VOH : 2.4V
ibusy
Vcc
Ready
VCC
R/B#
open drain output
VOL : 0.4V, VOH : 2.4V
VOH
C
L
VOL
Busy
tf
tr
GND
Device
Rp vs. tr, tf and Rp vs. ibusy
@ Vcc = 3.3V, Ta = 25°C, C
L
=50 pF
200
ibusy [A]
ibusy [A]
3m
2.4
ibusy
300n
3m
2m
1m
150
1.2
200n
100n
2m
1m
100
0.8
tr
50
0.6
1.8
1.8
1.8
tf
1.8
tr,tf [c]
1k
2k
3k
4k
Rp(ohm)
Rp value guidence
Vcc (Max.) - VOL (Max.)
3.2V
Rp (min. 3.3V part) =
=
I
OL +∑I
L
8mA + ∑I
L
where IL is the sum of the input currents of all devices tied to the R/B# pin.
Rp(max) is determined by maximum permissible limit of tr.
36
Spansion® SLC NAND Flash Memory for Embedded
S34ML01G1_04G1_10 September 6, 2012
SPANSION [ SPANSION ]
