XC9536XL-10VQG44C

The XC9536XL-10VQG44C is the smallest member of Xilinx’s XC9500XL CPLD family, offering 36 macrocells in a compact 44-pin Very Thin QFP package. Designed for low-cost, high-performance 3.3V systems, this device is ideal for replacing discrete logic, implementing simple state machines, and providing basic bus interfacing in consumer, computing, and communications applications.

Built on Xilinx’s FastFLASH technology (0.35 micron CMOS), the XC9536XL delivers 5 ns pin-to-pin delays and system frequencies up to 178 MHz – surprisingly fast for a device of this density and cost. The architecture consists of two Function Blocks (FBs), each with 18 macrocells, connected by the FastCONNECT II switch matrix. The FastCONNECT II structure provides fully predictable, uniform routing delays, a key advantage that ensures pin-locked performance: design changes within the same pinout do not affect timing.

Each macrocell has five direct product terms for implementing combinational logic, plus access to the product term allocator which can provide up to 90 product terms per macrocell from other macrocells in the same Function Block. The flip-flop in each macrocell is individually configurable as D, T, JK, or SR type, and can be clocked by any of the three global clocks or by a product-term generated clock. Output enable, set, and reset are also individually configurable.

The VQFP-44 package has a compact 10 x 10 mm footprint with 0.8 mm lead pitch, providing 34 user I/O pins in a form factor well-suited for space-constrained designs. The I/Os are 5V tolerant on the input side, allowing seamless interfacing with legacy 5V logic families, while outputs operate at 3.3V or 2.5V as determined by the VCCIO supply.

In-system programming via the standard JTAG interface enables programming on the board, which is useful for both manufacturing and field upgrades. With 10,000+ program/erase cycles and 20-year data retention, the XC9536XL offers reliability comparable to mask-programmed logic devices while retaining the flexibility of in-system reconfiguration. The XC9536XL is pin-compatible with the 5V XC9536 device, simplifying voltage migration.

The XC9536XL is a Flash-based Complex Programmable Logic Device. Its architecture and operation are as follows:

1. Function Blocks (FBs): Two Function Blocks, each containing 18 macrocells. Each FB has 54 inputs coming from the FastCONNECT II switch matrix and 18 macrocell outputs feeding back into the switch matrix. The wide 54-input structure allows complex combinatorial functions to be implemented in a single level of logic, contributing to the fast 5 ns pin-to-pin delay.

2. Macrocells: Each macrocell contains:
– An AND array generating five direct product terms
– An OR gate summing the product terms
– A product term allocator that can borrow up to 90 product terms from other macrocells in the same FB for complex logic functions
– A programmable flip-flop (configurable as D, T, JK, SR, or latch, or bypassed for combinatorial output)
– Exclusive-OR gate for output polarity selection (active high or low)
– Output enable multiplexer selecting from global OE, product-term OE, or always enabled
– Individual clock, set, and reset controls

3. FastCONNECT II Switch Matrix: The central routing resource that connects all I/O pins and FB outputs to the FB inputs. Unlike FPGAs where routing delay varies depending on path length, the FastCONNECT matrix provides uniform, predictable delay for all connections. This deterministic timing model is the foundation of the XC9500XL’s pin-locking guarantee – logic changes within a locked pinout do not change timing performance.

4. I/O Blocks (IOBs): Each IOB interfaces between internal logic and the external pin. Key features:
– Input buffer with Schmitt trigger hysteresis for improved noise immunity
– Output driver with programmable slew rate (fast for high-speed, slow for EMI reduction)
– Bus-hold circuit holding unused inputs at their last logic level (eliminates external pull-up/down resistors)
– 5V input tolerance (accepts voltages up to 5.5V even though VCC is 3.3V)
– Output voltage determined by VCCIO (2.5V or 3.3V)
– Hot-plug safe (I/Os do not drive during power-up/down)

5. Global Resources:
– 3 global clock pins (GCK1-3): low-skew distribution to all 36 macrocells
– 2 global output enable pins (GTS1-2): global tri-state control
– 1 global set/reset (GSR): asynchronous initialization of all flip-flops
All global pins are shared with I/O pins and can be used as regular I/O when the global function is not needed.

6. JTAG Boundary Scan and ISP: The JTAG interface provides both IEEE 1149.1 boundary-scan test capability and in-system programming capability. A single 4-pin JTAG port serves both functions. Programming is done concurrently across all macrocells, resulting in very fast programming times. The configuration is stored in non-volatile Flash cells, so the device is “instant-on” at power-up – no external configuration memory needed.

Package: VQG44 – 44-pin Very Thin Quad Flat Pack. Body dimensions: 10mm x 10mm x 1.0mm (typical height). Lead pitch: 0.8mm. 11 pins per side (44 total). Gull-wing leads. VQ = Very thin QFP. G = Green / lead-free. Commercial temperature grade: 0 degC to +70 degC ambient. MSL Level 3 (168 hours floor life).

• Computer Motherboard and Peripheral Logic: Glue logic, address decoding, and simple state machine functions on PC motherboards, graphics cards, storage controllers, and expansion cards. The low cost and small footprint make it ideal for replacing a handful of discrete logic gates in cost-sensitive computer designs.
• Consumer Electronics: Control logic in consumer devices including set-top boxes, DVD/Blu-ray players, gaming consoles, and home networking equipment. 36 macrocells are sufficient for many system control, I/O expansion, and user interface functions in consumer products.
• Bus Interface and Level Translation: 5V to 3.3V level shifting and bus interfacing between different voltage domains. The 5V tolerant inputs make the XC9536XL ideal for bridging legacy 5V systems to modern 3.3V designs without external level translators.
• Address Decoding and Glue Logic Replacement: Replacing PALs, GALs, and multiple discrete logic gates (AND, OR, XOR, flip-flops) with a single CPLD. Reduces component count, PCB area, and BOM cost while adding the flexibility of in-system reprogramming.
• Power Supply Sequencing and Monitoring: Power-on reset, voltage sequencing, and fault detection circuits for multi-voltage systems including servers, networking equipment, and embedded systems. The instant-on Flash configuration ensures the CPLD is active before other components come up.
• System Configuration and Control Logic: Board-level control functions including configuration state machines for FPGAs/processors, watchdog timers, and system status monitoring. The 34 I/O pins provide ample connectivity for a typical board management function.
• Keyboard and Display Controllers: Matrix keyboard scanners, LED display drivers, and simple user interface controllers for appliances, industrial control panels, and consumer devices. The 36 macrocells handle basic scanning and debouncing logic with ease.
• Quick-Turn Prototyping and Development Boards: FPGA/MCU development boards, evaluation kits, and prototyping platforms where the CPLD serves as a flexible glue-logic and level-shifting element that can be reprogrammed as the design evolves, reducing the need for multiple board spins during development.