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Texas Instruments SN74HCS245RKSR
- Part No.:
- SN74HCS245RKSR
- Manufacturer:
- Texas Instruments
- Package:
- 20-VFQFN Exposed Pad
- Datasheet:
-
SN74HCS245RKSR.pdf
- Description:
- SCHMITT-TRIGGER INPUT OCTAL BUS
- Quantity:
- Payment:
- Shipping:
Inventory:2,901
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Product details
Overview
SN74HCS245 from Texas Instruments is an octal bus transceiver IC with 3-state outputs and Schmitt-trigger inputs, operating across 2 V to 6 V supply. It features ±7.8-mA output drive at 6 V, 100 nA typical ICC, and –40°C to +125°C ambient operation. It enables bidirectional data flow between two 8-bit buses in industrial control backplanes and noisy sensor interface subsystems.
For engineers reviewing the SN74HCS245 datasheet, SN74HCS245 pinout, SN74HCS245 application, or SN74HCS245 equivalent, key selection criteria include Schmitt-trigger noise immunity, 3-state bus isolation capability, wide-voltage CMOS compatibility, and thermal performance in compact VQFN packaging.
Technical Context
The SN74HCS245 implements dual-directional CMOS transceivers controlled by a single DIR pin and globally enabled/disabled via active-low OE. Each of its eight channels supports A↔B bidirectional signal routing with automatic high-impedance state enforcement when disabled.
Schmitt-trigger inputs provide hysteresis (ΔVT = 0.6 V min at 6 V), enabling reliable operation with slow-rising signals and rejecting noise up to ±0.3 V peak-to-peak. Output switching characteristics are specified at CL = 50 pF, with tpd = 7 ns typ at 6 V and tt = 6 ns typ for transition time.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Supply Voltage Range | 2 V to 6 V - supports direct interfacing with 3.3 V and 5 V logic domains without level shifters |
| Output Drive Strength | ±7.8 mA at 6 V - sufficient to drive moderate capacitive loads (≤50 pF) and multiple CMOS inputs |
| Quiescent Supply Current | 100 nA typical - enables ultra-low-power operation in battery-backed or always-on monitoring systems |
| Input Hysteresis (ΔVT) | 0.6 V min at 6 V - rejects noise and stabilizes response to slow-switching mechanical inputs like switches or encoders |
| Propagation Delay | 7 ns typical at 6 V - ensures timing integrity in high-speed digital interconnects up to ~70 MHz data rates |
| Operating Temperature | –40°C to +125°C - qualified for under-hood automotive, industrial PLC, and outdoor embedded applications |
| ESD Rating (HBM) | ±4000 V - provides robust handling during board assembly and field service without external protection |
Pinout & Package
RKS package is a 20-pin VQFN (4.50 mm × 2.50 mm) with exposed thermal pad; suitable for space-constrained PCB layouts requiring efficient heat dissipation.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| DIR (Pin 1) | Direction control input | L selects B→A data flow; H selects A→B - enables single-wire bus arbitration in shared-memory or peripheral interfaces |
| OE (Pin 19) | Active-low output enable | Drives all outputs to high-impedance when high - essential for bus contention avoidance in multi-master systems |
| A1–A8 (Pins 2–9) | Port A I/O terminals | Eight bidirectional data lines tied to local controller or microcontroller GPIO banks |
| B1–B8 (Pins 11–18) | Port B I/O terminals | Eight bidirectional data lines connected to external peripherals, sensors, or legacy parallel buses |
| VCC (Pin 20) | Positive supply | Must be decoupled with 0.1 µF capacitor placed adjacent to pin - critical for stable switching and noise immunity |
| GND (Pin 10) | Ground reference | Return path for all I/O and supply currents; thermal pad (RKS only) may be connected to GND for improved thermal resistance |
Key Features
| Feature | Design Value |
|---|---|
| Schmitt-trigger inputs | Enables reliable interfacing with slow or noisy signals (e.g., mechanical switches, long traces) without external conditioning |
| 3-state outputs with common OE | Allows dynamic bus sharing among multiple devices on same trace - prevents signal contention in multiplexed architectures |
| Ultra-low ICC (100 nA typ) | Reduces system standby power in always-on monitoring nodes - supports >10-year battery life in low-duty-cycle IoT edge sensors |
| Wide 2–6 V supply range | Eliminates need for dedicated voltage translators when connecting mixed-voltage subsystems (e.g., 3.3 V MCU ↔ 5 V legacy peripheral) |
| –40°C to +125°C operation | Validated for deployment in harsh environments including motor drives, industrial automation cabinets, and automotive body controllers |
Applications
| Industrial Backplane Interface | Automotive Sensor Hub |
|---|---|
|
Use Scenario: Isolating and translating data between a 3.3-V microcontroller and legacy 5-V parallel I/O modules in programmable logic controllers. IC Role / Device Role / Timing Role: Bidirectional bus transceiver managing direction and tristate control to prevent bus conflicts during firmware updates or hot-swap events. Use Value: Schmitt-trigger inputs tolerate voltage droop and EMI on long backplane traces; 3-state outputs allow seamless insertion/removal of modules without system reset. |
Use Scenario: Aggregating signals from multiple slow-switching automotive cabin sensors (door latch, seat position, HVAC damper) into a central domain controller. IC Role / Device Role / Timing Role: Signal conditioner and bus driver that debounces mechanical contacts and buffers noisy analog switch outputs before ADC sampling. Use Value: Input hysteresis eliminates false triggers from vibration-induced contact bounce; wide temperature range ensures reliability across cold-soak to desert-heat conditions. |
| IoT Edge Node Data Multiplexer | Test Equipment Digital I/O Expander |
|
Use Scenario: Sharing a single UART or SPI interface across multiple low-power environmental sensors (temperature, humidity, CO₂) in a battery-operated wireless node. IC Role / Device Role / Timing Role: Low-quiescent-current bus switch enabling time-division multiplexing of sensor data onto a shared serial link. Use Value: 100 nA ICC minimizes idle current draw; 3-state outputs isolate inactive sensors to prevent leakage and crosstalk during measurement cycles. |
Use Scenario: Adding 16 configurable digital I/O lines to automated test equipment using a single 20-pin footprint, supporting both input capture and output stimulus generation. IC Role / Device Role / Timing Role: Programmable bidirectional I/O expander with synchronized direction control and glitch-free state transitions during pattern generation. Use Value: Precise 7 ns propagation delay and 6 ns transition time ensure sub-100 ns timing resolution; ±4 kV HBM ESD rating withstands repeated probe contact in lab environments. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar octal transceiver applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| SN74HCS245PWR | Same silicon die, DGS (SOT-20) package - larger 5.10 mm × 3.00 mm footprint, higher RθJA (124.3°C/W) | Better suited for prototyping or manual soldering due to wider pin pitch; less optimal for thermally constrained high-density boards | Select when hand assembly, rework, or thermal margin above 75°C/W is acceptable |
| SN74LV245AQPWRQ1 | Automotive-grade (AEC-Q100), LV logic family - 1.65–5.5 V range, lower drive (±16 mA), no Schmitt inputs | Requires external filtering for noisy inputs; limited to ≤105°C ambient unless derated; certified for automotive safety-critical use | Select only when AEC-Q100 qualification is mandatory and Schmitt-trigger functionality is not required |
Compared with SN74HCS245PWR, the SN74HCS245RKSR offers superior thermal performance (RθJA = 75.6°C/W) and smaller PCB area; compared with SN74LV245AQPWRQ1, it delivers inherent noise immunity and extended temperature support without design compromises.
Availability
SN74HCS245RKSR is available at Aetrix Electronics and suitable for industrial backplanes, automotive sensor hubs, IoT edge nodes, and test equipment digital I/O expansion requiring stable component supply and long-term manufacturability.
Supply support for SN74HCS245RKSR 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
Texas Instruments is a global semiconductor leader delivering analog and embedded processing solutions with emphasis on reliability, precision, and energy efficiency across industrial, automotive, and personal electronics markets.
The SN74HCS245 belongs to TI's HCS logic family - designed specifically for robust, low-power, wide-voltage digital interfacing in harsh or space-constrained environments where noise immunity and thermal stability are critical.
FAQ
What is the maximum capacitive load the SN74HCS245RKSR can drive while maintaining specified timing?
The SN74HCS245RKSR is characterized for CL = 50 pF in its switching specifications - propagation delay, enable/disable times, and transition times are guaranteed only up to this load. Driving larger capacitances increases delay and may cause signal integrity issues such as ringing or undershoot; layout best practices recommend keeping total trace + receiver capacitance ≤50 pF for full spec compliance. The SN74HCS245RKSR datasheet explicitly states this limit in Section 9.2.1.1.
How should unused inputs on the SN74HCS245RKSR be terminated?
Unused inputs on the SN74HCS245RKSR must be tied to either VCC or GND - never left floating - to prevent undefined logic states and excessive current draw. TI recommends 10-kΩ pull-up or pull-down resistors for unused A/B channel pins, as stated in Section 8.3.2 and Figure 8-2 of the datasheet. This ensures stable operation and avoids increased dynamic current caused by indeterminate input voltages near switching thresholds.
Does the SN74HCS245RKSR support true bidirectional data flow on each channel?
Yes, the SN74HCS245RKSR supports true bidirectional data flow per channel via the DIR pin: when DIR = L, data flows from Port B to Port A; when DIR = H, data flows from Port A to Port B. Both directions are implemented with matched drive strength and identical electrical characteristics, as confirmed in the Function Table (Table 8-1) and Electrical Characteristics section of the SN74HCS245RKSR datasheet.
Can the thermal pad on the SN74HCS245RKSR RKS package be left unconnected?
Yes, the thermal pad on the SN74HCS245RKSR RKS package may be left floating, though TI recommends connecting it to GND for improved thermal performance and EMI suppression. Section 5.1 of the datasheet states: "The thermal pad can be connect to GND or left floating. Do not connect to any other signal or supply." Leaving it unconnected does not affect electrical functionality but increases junction-to-ambient thermal resistance by ~25°C/W versus GND connection.
What is the minimum recommended pull-up resistor value for the OE pin during power-up?
Texas Instruments specifies that the OE pin should be tied to VCC through a pull-up resistor to ensure high-impedance outputs during power-up or power-down sequences. A 10-kΩ resistor is typically sufficient, as stated in Section 8.1 - it balances leakage current limits (±100 nA max II) and driver sink capability while guaranteeing OE remains asserted high until system initialization completes. The SN74HCS245RKSR datasheet confirms this value in the "Power-Up/Down Considerations" subsection.
SN74HCS245RKSR Specifications
- Product attributes
- Attribute value
- Manufacturer:
- Texas Instruments
- Series:
- 74HC
- Package/Case:
- 20-VFQFN Exposed Pad
- Packaging:
- Tape & Reel (TR)
- Product Status:
- Active
- Logic Type:
- Transceiver, Non-Inverting
- Number of Elements:
- 1
- Number of Bits per Element:
- 8
- Input Type:
- Schmitt Trigger
- Output Type:
- 3-State
- Current - Output High, Low:
- 7.8mA, 7.8mA
- Voltage - Supply:
- 2V ~ 6V
- Operating Temperature:
- -40°C ~ 125°C (TA)
- Grade:
- -
- Qualification:
- -
- Mounting Type:
- Surface Mount, Wettable Flank
- Supplier Device Package:
- 20-VQFN (2.5x4.5)
SN74HCS245RKSR FAQ
1.How can I place an order for SN74HCS245RKSR through Aetrix?
Please submit a Request for Quotation (RFQ) for SN74HCS245RKSR on Aetrix. Our sales agent will provide a competitive quotation and guide you through the order confirmation once you accept the terms.
2.Are the price and stock information for SN74HCS245RKSR reliable?
The price and inventory of SN74HCS245RKSR are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for SN74HCS245RKSR is usually 5 days.
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4.How is shipping managed for SN74HCS245RKSR?
SN74HCS245RKSR orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your SN74HCS245RKSR order is processed, you will receive an email with the shipment details and tracking number.
Note: Tracking information may take up to 24 hours to appear. Express delivery typically takes 3–5 business days.
5.How can I obtain technical support or documentation for SN74HCS245RKSR?
For technical support, including SN74HCS245RKSR datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your SN74HCS245RKSR requirements.
6.How does Aetrix verify that SN74HCS245RKSR is sourced from the original manufacturer or authorized distributors?
All SN74HCS245RKSR products on Aetrix are procured from qualified distributors and authorized channels. Our dedicated quality assurance team conducts strict verification, including traceability checks and, if necessary, third-party testing. This ensures that SN74HCS245RKSR meets industry standards.
7.What is the process for return or replacement of SN74HCS245RKSR?
All SN74HCS245RKSR units undergo pre-shipment inspection (PSI). If there is an issue with SN74HCS245RKSR, returns or replacements are accepted under the following conditions:
1.Quantity discrepancies, incorrect items, or visible external defects (such as breakage or corrosion), acknowledged by Aetrix.
2.The issue is reported within 90 days of delivery.
3.The SN74HCS245RKSR part is unused and in its original packaging.
Return procedure for SN74HCS245RKSR:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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