PSD835G2V-12U STMicroelectronics, PSD835G2V-12U Datasheet - Page 88

• Manufacturer Part Number: PSD835G2V-12U
• Manufacturer: STMicroelectronics

Specifications of PSD835G2V-12U

• Operating Temperature (max): 70C
• Operating Temperature (min): 0C
• Operating Temperature Classification: Commercial
• Package Type: TQFP
• Mounting: Surface Mount
• Pin Count: 80
• Lead Free Status / Rohs Status: Compliant

Power management
18
88/120
Power management
The PSD835G2V offers configurable power saving options. These options may be used
individually or in combinations, as follows:
●
●
●
●
All memory blocks in a PSD (primary and secondary Flash memory, and SRAM) are
built with Power Management technology. In addition to using special silicon design
methodology, power management technology puts the memories into standby mode
when address/data inputs are not changing (zero DC current). As soon as a transition
occurs on an input, the affected memory “wakes up”, changes and latches its outputs,
then goes back to standby. The designer does not have to do anything special to
achieve memory standby mode when no inputs are changing—it happens
automatically.
The PLD sections can also achieve Standby mode when its inputs are not changing, as
described in the sections on the Power Management mode registers (PMMR).
As with the Power Management mode, the Automatic Power Down (APD) unit allows
the PSD to reduce to standby current automatically. The APD Unit can also block MCU
address/data signals from reaching the memories and PLDs. This feature is available
on all the devices of the PSD family. The APD Unit is described in more detail in
Section 18.1: Automatic Power-down (APD) unit and Power-down
Built-in logic monitors the Address Strobe of the MCU for activity. If there is no activity
for a certain time period (MCU is asleep), the APD Unit initiates Power-down mode (if
enabled). Once in Power-down mode, all address/data signals are blocked from
reaching PSD memory and PLDs, and the memories are deselected internally. This
allows the memory and PLDs to remain in standby mode even if the address/data
signals are changing state externally (noise, other devices on the MCU bus, etc.). Keep
in mind that any unblocked PLD input signals that are changing states keep the PLD
out of Standby mode, but not the memories.
PSD Chip Select Input (CSI, PD2) can be used to disable the internal memories,
placing them in standby mode even if inputs are changing. This feature does not block
any internal signals or disable the PLDs. This is a good alternative to using the APD
Unit. There is a slight penalty in memory access time when PSD Chip Select Input
(CSI, PD2) makes its initial transition from deselected to selected.
The PMMRs can be written by the MCU at run-time to manage power. All PSD devices
support “blocking bits” in these registers that are set to block designated signals from
reaching both PLDs. Current consumption of the PLDs is directly related to the
composite frequency of the changes on their inputs (see
savings can be achieved by blocking signals that are not used in PLD logic equations at
run-time. PSDsoft creates a fuse map that automatically blocks the low address byte
(A7-A0) or the Control signals (CNTL0-CNTL2, ALE and WRH/DBE) if none of these
signals are used in PLD logic equations.
PSD devices have a Turbo bit in PMMR0. This bit can be set to turn the Turbo mode off
(the default is with Turbo mode turned on). While Turbo mode is off, the PLDs can
achieve standby current when no PLD inputs are changing (zero DC current). Even
when inputs do change, significant power can be saved at lower frequencies (AC
current), compared to when Turbo mode is on. When the Turbo mode is on, there is a
significant DC current component and the AC component is higher.
Doc ID 10585 Rev 3
Figure
33). Significant power
mode.
PSD835G2V