PSD935G2-90U STMicroelectronics, PSD935G2-90U Datasheet - Page 6

• Manufacturer Part Number: PSD935G2-90U
• Manufacturer: STMicroelectronics

Specifications of PSD935G2-90U

• 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

PSD935G2
4.0
PSD9XX
Architectural
Overview
PSD9XX devices contain several major functional blocks. Figure 1 on page 3 shows the
architecture of the PSD9XX device family. The functions of each block are described
briefly in the following sections. Many of the blocks perform multiple functions and are user
configurable.
4.1 Memory
The PSD935G2 contains the following memories:
Each of the memories is briefly discussed in the following paragraphs. A more detailed
discussion can be found in section 9.
The 4 Mbit Flash is the main memory of the PSD935G2. It is divided into eight
equally-sized sectors that are individually selectable.
The 256 Kbit secondary Flash memory is divided into four equally-sized sectors. Each
sector is individually selectable.
The 64 Kbit SRAM is intended for use as a scratchpad memory or as an extension to the
microcontroller SRAM. If an external battery is connected to the PSD9XX’s Vstby pin, data
will be retained in the event of a power failure.
Each block of memory can be located in a different address space as defined by the user.
The access times for all memory types includes the address latching and DPLD decoding
time.
4.2 PLDs
The device contains two PLD blocks, each optimized for a different function, as shown in
Table 2. The functional partitioning of the PLDs reduces power consumption, optimizes
cost/performance, and eases design entry.
The Decode PLD (DPLD) is used to decode addresses and generate chip selects for
the PSD935G2 internal memory and registers. The General Purpose PLD (GPLD) can
implement user-defined external chip selects and logic functions. The PLDs receive their
inputs from the PLD Input Bus and are differentiated by their output destinations, number
of Product Terms.
The PLDs consume minimal power by using Zero-Power design techniques. The speed
and power consumption of the PLD is controlled by the Turbo Bit in the PMMR0 register
and other bits in the PMMR2 registers. These registers are set by the microcontroller at
runtime. There is a slight penalty to PLD propagation time when invoking the non-Turbo
bit.
4.3 I/O Ports
The PSD935G2 has 52 I/O pins divided among seven ports (Port A, B, C, D, E, F and G).
Each I/O pin can be individually configured for different functions. Ports can be configured
as standard MCU I/O ports, PLD I/O, or latched address outputs for microcontrollers using
multiplexed address/data busses.
The JTAG pins can be enabled on Port E for In-System Programming (ISP). Ports F and
G can also be configured as a data port for a non-multiplexed bus.
4.4 Microcontroller Bus Interface
The PSD935G2 easily interfaces with most 8-bit microcontrollers that have either
multiplexed or non-multiplexed address/data busses. The device is configured to respond
to the microcontroller’s control signals, which are also used as inputs to the PLDs. Section
9.3.5 contains microcontroller interface examples.
Table 2. PLD I/O Table
Decode PLD
General PLD
•
•
•
4 Mbit Flash
A secondary 256 Kbit Flash memory for boot or data
64 Kbit SRAM.
Name
Abbreviation
GPLD
DPLD
Inputs
66
66
PSD9XX Family
Outputs
15
24
Product Terms
136
40
5