PSD4235G2V-10U STMICROELECTRONICS [STMicroelectronics], PSD4235G2V-10U Datasheet - Page 72

• Manufacturer Part Number: PSD4235G2V-10U
• Description: Flash In-System Programmable (ISP) Peripherals for 16-bit MCUs
• Manufacturer: STMICROELECTRONICS [STMicroelectronics]

PSD4256G6V
Other Power Saving Options
The PSD offers other reduced power saving op-
tions that are independent of the Power-down
mode. Except for the SRAM Standby and PSD
Chip Select Input (CSI, PD2) features, they are en-
abled by setting bits in PMMR0 and PMMR2 (as
summarized in Table 23 and Table 24, page 23).
PLD Power Management
The power and speed of the PLDs are controlled
by the Turbo bit (bit 3) in PMMR0. By setting the
bit to 1, the Turbo mode is off and the PLDs con-
sume the specified standby current when the in-
puts are not switching for an extended time of
70 ns. The propagation delay time is increased af-
ter the Turbo bit is set to 1 (turned off) when the in-
puts change at a composite frequency of less than
15 MHz. When the Turbo bit is reset to ’0’ (turned
on), the PLDs run at full power and speed. The
Turbo bit affects the PLD’s DC power, AC power,
and propagation delay. See the AC and DC char-
acteristics tables for PLD timing values (Table 68).
Blocking MCU control signals with the PMMR2 bits
can further reduce PLD AC power consumption.
SRAM Standby Mode (Battery Backup)
The PSD supports a battery backup mode in which
the contents of the SRAM are retained in the event
of a power loss. The SRAM has Voltage Standby
(V
battery. When V
then the PSD automatically connects to Voltage
Standby (V
SRAM. The SRAM standby current (I
cally 0.5 µA. The SRAM data retention voltage is
2V minimum. The Battery-on Indicator (V
can be routed to PE7. This signal indicates when
the V
SRAM is running on battery power.
PSD Chip Select Input (CSI, PD2)
PD2 of Port D can be configured in PSDsoft as
PSD Chip Select Input (CSI). When Low, the sig-
nal selects and enables the internal primary Flash
memory, secondary Flash memory, SRAM, and I/
O blocks for READ or WRITE operations involving
the PSD. A High on PSD Chip Select Input (CSI,
PD2) disables the primary Flash memory, second-
ary Flash memory, and SRAM, and reduces the
PSD power consumption. However, the PLD and
72/100
This is preliminary information on a new product now in development or undergoing evaluation. Details are subject to change without notice.
STBY
CC
, PE6) that can be connected to an external
has dropped below V
STBY
, PE6) as a power source to the
CC
becomes lower than V
STBY
, and that the
STBY
) is typi-
BATON
STBY
)
I/O signals remain operational when PSD Chip Se-
lect Input (CSI, PD2) is High.
There may be a timing penalty when using PSD
Chip Select Input (CSI, PD2) depending on the
speed grade of the PSD that you are using. See
the timing parameter t
Input Clock
The PSD provides the option to turn off CLKIN
(PD1) to the PLD to save AC power consumption.
CLKIN (PD1) is an input to the PLD AND Array and
the Output Macrocells (OMC).
During Power-down mode, or, if CLKIN (PD1) is
not being used as part of the PLD logic equation,
the clock should be disabled to save AC power.
CLKIN (PD1) is disconnected from the PLD AND
Array or the Macrocells block by setting bits 4 or 5
to a 1 in PMMR0.
Figure 33. Enable Power-down Flow Chart
No
by setting PMMR0 bits 4 and 5
Disable desired inputs to PLD
and PMMR2 bits 0 to 6.
Set PMMR0 Bit 1 = 1
PSD in Power
OPTIONAL
for 15 CLKIN
Enable APD
ALE/AS idle
Down Mode
clocks?
SLQV
RESET
Yes
in Table 68.
AI04940