
K9F6408U0B-TCB0, K9F6408U0B-TIB0
FLASH MEMORY
25
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 reg-
ister 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 11). Its value can
be determined by the following guidance.
V
CC
R/B
open drain output
Device
GND
where I
L
is the sum of the input currents of all devices tied to the R/B pin.
Rp
t
I
Rp(ohm)
Fig 12 Rp vs tr ,tf & Rp vs ibusy
Ibusy
tr
Rp value guidance
Rp(max) is determined by maximum permissible limit of tr
ibusy
Rp(min) =
V
CC
(Max.) - V
OL
(Max.)
I
OL
+
Σ
I
L
=
3.2V
8mA
+
Σ
I
L
Busy
Ready Vcc
@ Vcc = 3.3V, Ta = 25
°
C , C
L
= 100pF
2.0V
tf
tr
1K
2K
3K
4K
100n
200n
300n
3m
2m
1m
96
tf
189
290
381
4.2
4.2
4.2
4.2
3.3
1.65
1.1
0.825
0.8V