©2014 Silicon Storage Technology, Inc.

DS20005053B

04/14

9

4 Mbit (x16) Multi-Purpose Flash Plus

SST39VF401C / SST39VF402C / SST39LF401C / SST39LF402C

Data Sheet

Ready/Busy# (RY/BY#)

The devices include a Ready/Busy# (RY/BY#) output signal. RY/BY# is an open drain output pin that

indicates whether an Erase or Program operation is in progress. Since RY/BY# is an open drain out-

edge of the final WE# pulse in the command sequence, the RY/BY# status is valid.

When RY/BY# is actively pulled low, it indicates that an Erase or Program operation is in progress.

When RY/BY# is high (Ready), the devices may be read or left in standby mode.

When the SST39VF401C/402C and SST39LF401C/402C are in the internal Program operation, any

ing the completion of an internal Write operation, the remaining data outputs may still be invalid: valid data on

the entire data bus will appear in subsequent successive Read cycles after an interval of 1 µs. During internal

pulse for Program operation. For Sector-, Block- or Chip-Erase, the Data# Polling is valid after the ris-

ing edge of sixth WE# (or CE#) pulse. See Figure 9 for Data# Polling timing diagram and Figure 23 for

a flowchart.

Toggle Bits (DQ6 and DQ2)

alternating ‘1’s and ‘0’s, i.e., toggling between 1 and 0. When the internal Program or Erase operation

whether a particular sector is being actively erased or erase-suspended. Table 3 shows detailed status

Write operation. See Figure 10 for Toggle Bit timing diagram and Figure 23 for a flowchart.

Table 3: Write Operation Status

Status

RY/BY#

Normal Operation

Standard Program

Toggle

No Toggle

0

Standard Erase

0

Toggle

Toggle

0

Erase-Suspend

Mode

Read from Erase-Sus-

pended Sector/Block

1

1

Toggle

1

Read from Non-Erase-

Suspended Sector/Block

Data

Data

Data

1

Program

Toggle

N/A

0

T3.0 25053