Datasheet

Theory of operation STPM01
38/60 Doc ID 10853 Rev 8
– RD mode signal has been already described in the SPI section but there is another
implied function of the signal RD. When it is set, each sense amplifier is disconnected
from corresponding antifuse element and this way, its 3 V NMOS gate is protected
from the high voltage of VOTP during permanent write operation. This means that as
long as the VOTP voltage reads more than 3 V, the signal RD should be set.
– PUMP: when set, the PUMP mode signal transform the MOP and MON pins to act as
driving signals to implement a charge-pump DC-DC converter (see schematic page
36). This feature is useful in order to boost the V
CC
supply voltage of the STPM01 to
generate the VOTP voltage (14 V to 20 V) needed to program the OTP antifuse
elements.
– CSEL In normal operation, if the anti-tamper module is not activated (see PST
configuration bits) the STPM01 will select the channel 1 as source of current
information. For debug or calibration purposes it is possible to select channel 2 as
source of current channel signal when the tamper module is disabled. This is done
setting CSEL mode bit.
– WE (write enable): This mode signal is used to permanently write to the OTP antifuse
element. When this bit is not set, any write to the configuration bit is recorded in the
shadow latches. When this bit is set the writing is recorded both in the shadow latch
and in the OTP antifuse element.
– Precharge: this command swaps the sequence of data record read, allowing the
reading of the last four data records as first and the first four as second. The reading
sequence will be 5, 6, 7, 8, 1, 2, 3, 4. Differently from the other mode signals, the
precharge command is not retained inside the STPM01, in fact it should be sent each
time before the reading of the data records. This is the only command that can be
sent to STPM01 when the TSTD bit has been set.
Table 17. Mode signals description
Bit #
Signal
name
Bit
value
Status
Binary
command
Hex
command
0 BANK
0
Used for RC startup procedure
0111000x 70 or 71
1 1111000x F0 or F1
1PUMP
0 MOP and MON operates normally 0111001x 72 or 73
1
MOP and MON provides the driving signals to implement a
charge-pump DC-DC converter
1111001x F2 or F3
2 Reserved
3 Reserved
4 CSEL
0 Current Channel 1 selected when tamper is disabled 0111100x 78 or 79
1 Channel 2 selected when tamper is disabled 1111100x F8 or F9
5RD
0 The 56 Configuration bits originated by OTP antifuses 0111101x 7A or 7B
1 The 56 Configuration bits originated by shadow latches 1111101x FA or FB
6WE
0
Any writing in the configuration bits is recorded in the
shadow latches
0111110x 7C or 7D
1
Any writing in the configuration bits is recorded both in the
shadow latches and in the OTP antifuse elements
1111110x FC or FD
7 Precharge 1
Swap the 32 bits data records reading. From
1,2,3,4,5,6,7,8, to 5,6,7,8,1,2,3,4 and viceversa
1111111x FF