NXP Semiconductors SC16C650BIBS,128

Overview

SC16C650BIBS,128 from NXP Semiconductors (formerly Philips) is a single-channel UART IC for embedded serial communication, converting parallel CPU data to asynchronous serial streams and vice versa. It delivers 32-byte transmit/receive FIFOs, IrDA 1.0 encoding/decoding up to 115.2 kbit/s, auto-RTS/CTS flow control, and supports 5 V / 3.3 V / 2.5 V operation across −40 °C to +85 °C - deployed in industrial PLCs, legacy PC peripherals, and infrared-enabled point-of-sale terminals.

For engineers reviewing the SC16C650BIBS,128 datasheet, SC16C650BIBS,128 pinout, SC16C650BIBS,128 application, or SC16C650BIBS,128 equivalent, key selection criteria include FIFO trigger level programmability, 3 Mbit/s max serial rate at 5 V, HVQFN32 thermal-enhanced packaging, IrDA v1.0 compliance, and register-level compatibility with ST16C650/TL16C650 software stacks.

Technical Context

The SC16C650BIBS,128 implements a dual-FIFO architecture with independent 32-byte TX/RX buffers, four selectable interrupt trigger levels per FIFO, and hardware/software flow control logic that monitors CTS/RTS or Xon/Xoff sequences without CPU intervention. Its baud rate generator accepts up to 48 MHz input clock and divides by programmable 16-bit divisors to achieve DC–3 Mbit/s rates, with BAUDOUT providing a 16× reference for external timing.

Internal register mapping follows 16C450 legacy addressing but extends functionality via Enhanced Feature Register (EFR), Xon/Xoff registers, and FIFO Control Register (FCR) bits enabling auto-RTS threshold behavior, DMA-ready signaling (TXRDY/RXRDY), and sleep mode activation - all accessible through standard 8-bit I/O bus cycles using A0–A2 address lines and CS0–CS2 chip selects.

Key Specifications

Pinout & Package

HVQFN32 package: plastic thermal-enhanced very thin quad flat package, 5 × 5 × 0.85 mm body, 32 terminals, no leads, exposed thermal pad (pin 32 = GND).

Key Features

Applications

Equivalent & Alternatives

The following parts are listed as comparable options for similar UART applications.

Compared with ST16C654CJ48 and TL16C750IPM, the SC16C650BIBS,128 uniquely balances legacy 16C450 software compatibility, triple-voltage operation, IrDA integration, and HVQFN32 space efficiency - making it optimal for cost-sensitive industrial retrofits where footprint and voltage flexibility outweigh raw FIFO depth.

Availability

SC16C650BIBS,128 is available at Aetrix Electronics and suitable for industrial automation, legacy PC peripheral upgrades, and infrared point-of-sale terminals requiring stable component supply and long-term lifecycle assurance.

Supply support for SC16C650BIBS,128 includes scheduled delivery planning, volume procurement assistance, BOM continuity management, traceable sourcing, and lifecycle availability coordination for OEM customers, industrial embedded developers, connected-device designers, and electronics production programs.

Manufacturer

NXP Semiconductors, headquartered in Eindhoven, Netherlands, develops high-reliability semiconductor solutions for automotive, industrial, and IoT markets with emphasis on long-lifecycle support and AEC-Q100/IEC 61508 compliance.

The SC16C650BIBS,128 belongs to NXP's legacy UART product line designed specifically for industrial control, telecom infrastructure, and embedded systems requiring drop-in 16C450/16C550 upgrade paths with enhanced FIFO and IrDA capabilities.

FAQ

What voltage levels does the SC16C650BIBS,128 support, and how does that affect system design?

The SC16C650BIBS,128 operates at 2.5 V, 3.3 V, or 5 V ±10%, with 5 V-tolerant inputs. This triple-voltage capability allows direct integration into mixed-rail systems - for example, interfacing a 3.3 V microcontroller bus to a 5 V RS-232 transceiver without level shifters. The SC16C650BIBS,128 maintains full functionality across all three supply voltages, including identical 32-byte FIFO behavior and IrDA timing, simplifying power domain partitioning in industrial backplanes.

Does the SC16C650BIBS,128 require an external crystal, or can it use an external clock signal?

The SC16C650BIBS,128 supports both configurations: a parallel-resonant crystal (e.g., 1.8432 MHz or 48 MHz) connected between XTAL1 and XTAL2, or a single-ended external clock applied to XTAL1 with XTAL2 left floating. In crystal mode, internal oscillator circuitry provides stable 16× baud reference; in external clock mode, the SC16C650BIBS,128 bypasses oscillator circuitry for jitter-sensitive applications like ISDN data pumps. Both methods feed the same programmable baud rate generator.

How does the auto-RTS function work in the SC16C650BIBS,128, and what trigger levels are available?

The SC16C650BIBS,128 auto-RTS asserts RTS low when RxFIFO contents reach one of four programmable thresholds: 8, 16, 24, or 28 bytes. RTS remains asserted until RxFIFO drops to the next lower threshold - e.g., if set to 16, RTS deasserts only when FIFO falls to ≤8 bytes. This hysteresis prevents rapid toggling during marginal receive loads. Configuration requires setting EFR[4] = 1 and writing FCR[6:5] to select level - a hardware-controlled mechanism eliminating software polling.

Is the SC16C650BIBS,128 pin-compatible with the ST16C650A, and what software changes are needed?

Yes, the SC16C650BIBS,128 is pin-compatible with the ST16C650A in HVQFN32 (SC16C650BIBS) and PLCC44 packages. After power-up, its registers default to 16C450-equivalent state, ensuring full compatibility with existing ST16C650A drivers. To enable advanced features (32-byte FIFOs, auto-flow control, IrDA), software must write to the Enhanced Feature Register (EFR) and FIFO Control Register (FCR) - no changes to core read/write I/O sequences are required.

What is the role of the DDIS pin on the SC16C650BIBS,128, and when should it be used?

The DDIS (Driver Disable) pin on the SC16C650BIBS,128 is an active-low output that disables external transceivers (e.g., RS-232 line drivers) during CPU read cycles to prevent bus contention. When the SC16C650BIBS,128 is not actively driving D0–D7, DDIS goes HIGH; during reads, it pulls LOW to tri-state the external driver. This feature is essential in shared-bus systems where multiple peripherals share the same data lines - ensuring clean signal integrity without external logic.