STLED316SMTR - 6-Digit LED Controller w/ Key Scan, SO-24 | STMicroelectronics
MPN: STLED316SMTR ✓ Active| Qty | Unit Price | Extended |
|---|---|---|
| 1 | $1.85 | $1.85 |
| 10 | $1.62 | $16.20 |
| 100 | $1.38 | $138.00 |
| 500 | $1.18 | $590.00 |
| 1,000 | $1.02 | $1,020.00 |
STLED316SMTR Overview
What is an LED display controller? An LED display controller (sometimes called an LED driver or display bias IC) is an interface device that sits between a microcontroller and a multiplexed 7-segment or dot-matrix LED panel. It receives display data over a low-pin-count serial bus (SPI, I2C, or proprietary) and re-drives each segment at the correct duty cycle, freeing the host MCU from software multiplexing. In the broader taxonomy, LED display controllers sit beneath LED Drivers -> Power Management -> Power & Interface ICs, and they are distinct from simple LED current sinks because they integrate the timing, brightness, and key-scan logic required for human-machine interface (HMI) panels.
Key features of the STLED316SMTR include 14 open-drain segment/digit outputs rated at 40 mA continuous, integrated 3-wire serial interface (clock, data, strobe) compatible with SPI mode 0, hardware key-scan with on-chip debounce, low standby current to support battery-backed panels, and a wide industrial operating temperature range. The device is also designed for minimum external BOM - only the segment current-setting resistor and decoupling caps are required, allowing very compact front-panel PCBs.
Typical applications include white-good front panels (washing machines, microwaves, ovens), industrial control HMIs, point-of-sale (POS) terminals, audio equipment displays, instrument cluster readouts, and any 6-digit or smaller 7-segment user interface requiring keypad scanning. With 8 segment + 6 digit outputs the controller can drive a 6-digit 7-segment display plus decimal points, or up to 8 separate status LEDs.
When designing with the STLED316SMTR, observe the absolute maximum segment current rating and choose the external RSET resistor accordingly. Ensure the 3-wire interface timing matches SPI mode 0 (CPOL=0, CPHA=0) of the host MCU, and place the decoupling capacitor as close as possible to VDD to suppress key-scan glitches during display multiplexing.
This page synthesises distributor pricing, parametric comparison with same-brand and cross-brand drop-in alternatives, and practical design notes that complement - but do not replace - the official STMicroelectronics datasheet.
Drop-in alternatives for STLED316SMTR — same package, pin-to-pin compatible. Different-package parts requiring PCB rework are excluded.
Quick Comparison Tool — Select alternative parts for side-by-side comparison:
STLED316S
✅ Drop-In📋 Reference alternative (not in catalog)
STLED316M
✅ Drop-In ⚠️ Specs Unverified📋 Reference alternative (not in catalog)
TM1637
✅ Drop-In📋 Reference alternative (not in catalog)
TM1638
✅ Drop-In📋 Reference alternative (not in catalog)
STLED316SMTR Maximum Ratings & Electrical Characteristics
| Product Type | Serial-interfaced 6-digit LED controller with key scan |
| Number of Segments | 8 (plus 6 digit drivers, 14 outputs total) |
| Number of Digits Supported | Up to 6 digits |
| Maximum Segment Output Current | 40 mA per segment |
| Output Configuration | Open-drain segment/digit drivers |
| Key-Scan Matrix | 2 x 2 (supports up to 4 keys) |
| Serial Interface | 3-wire SPI-compatible (clock, data, strobe) |
| Supply Voltage (VDD) | 4.5 V to 5.5 V |
| LED Forward Voltage Range | up to 3 V (LED front-panel drive) |
| Standby Current | Low (microamp-level standby mode) |
| Operating Temperature | -40 C to +85 C (industrial) |
| Package | 24-pin SO (SO-24, 7.5 mm body width) |
| Mounting Type | Surface Mount |
| Packaging | Tape & Reel (MTR suffix) |
| RoHS Compliance | Compliant (Pb-free) |
STLED316SMTR Pin Configuration
| Pin 1 | STB — Strobe / chip-select (active high) for 3-wire serial interface |
| Pin 2 | CLK — Serial clock input |
| Pin 3 | DIN — Serial data input |
| Pin 4 | GND — Ground |
| Pin 5 | SEG0 — Segment A driver output (open-drain) |
| Pin 6 | SEG1 — Segment B driver output (open-drain) |
| Pin 7 | SEG2 — Segment C driver output (open-drain) |
| Pin 8 | SEG3 — Segment D driver output (open-drain) |
| Pin 9 | SEG4 — Segment E driver output (open-drain) |
| Pin 10 | SEG5 — Segment F driver output (open-drain) |
| Pin 11 | SEG6 — Segment G driver output (open-drain) |
| Pin 12 | SEG7 — Decimal-point driver output (open-drain) |
| Pin 13 | DIG0 — Digit 0 common driver (open-drain) |
| Pin 14 | DIG1 — Digit 1 common driver (open-drain) |
| Pin 15 | DIG2 — Digit 2 common driver (open-drain) |
| Pin 16 | DIG3 — Digit 3 common driver (open-drain) |
| Pin 17 | DIG4 — Digit 4 common driver (open-drain) |
| Pin 18 | DIG5 — Digit 5 common driver (open-drain) |
| Pin 19 | KS0 — Key-scan row 0 |
| Pin 20 | KS1 — Key-scan row 1 |
| Pin 21 | KI0 — Key-scan input 0 |
| Pin 22 | KI1 — Key-scan input 1 |
| Pin 23 | VDD — Positive supply (4.5 V to 5.5 V) |
| Pin 24 | TEST — Test pin (leave open or connect to GND in production) |
Typical Applications
STLED316SMTR is suitable for 6 applications: White-Good Front Panels (Washing Machines, Microwaves, Ovens), Industrial Control HMIs and Process Indicators, Point-of-Sale (POS) Terminals, Audio Equipment Displays (Amps, Receivers, Mixers), Instrument Cluster Readouts (Bench Multimeters, Lab PSUs), Status / Counter Panels (Production Line Counters, Timers).
White-Good Front Panels (Washing Machines, Microwaves, Ovens)
The STLED316SMTR is purpose-built for white-good front-panel HMIs where a 6-digit 7-segment display shows time, temperature, or programme status. With 8 segment + 6 digit open-drain outputs at 40 mA per segment, it can directly drive standard red/green 7-segment LEDs without external drivers, while the integrated 2x2 key-scan handles Start/Pause/Reset/Option buttons. The 4.5-5.5 V supply matches the appliance 5 V rail, and the SO-24 package fits behind compact display windows. Compared to a discrete multiplexed solution, this part reduces BOM by ~10 components and frees MCU GPIOs.
Recommended
Industrial Control HMIs and Process Indicators
Industrial control panels often need to show 6-digit process values (flow rate, RPM, temperature) plus 4 function keys. The STLED316SMTR's industrial -40 C to +85 C operating range, 5 V supply tolerance, and built-in ESD protection on segment outputs suit 24 V cabinet environments when paired with appropriate isolation. The 3-wire SPI interface reduces wiring back to the main controller, and the low standby current supports battery-backed panel memory retention. Galvanic isolation on SPI is recommended when the panel sits >1 m from the controller.
Recommended
Point-of-Sale (POS) Terminals
POS terminals require a 6-digit price/total display plus 4 cashier keys (Clear, Subtotal, Cash, Enter). The STLED316SMTR directly drives the 7-segment price display and scans the 4 keypad buttons, removing the need for a dedicated keypad controller IC. Its SO-24 package is small enough for compact handheld POS housings, and the low standby current (~1 uA) extends battery life during card-payment wait states. Anti-tamper key matrices can be implemented by combining STLED316SMTR key-scan with the host MCU interrupt logic.
Recommended
Audio Equipment Displays (Amps, Receivers, Mixers)
Hi-Fi amplifiers and AV receivers traditionally use 6-digit volume/frequency readouts. The STLED316SMTR's clean 40 mA per-segment drive produces even brightness across the display without the LED-matching issues seen with discrete matrix designs. The 3-wire SPI bus shares the same pins as other front-panel ICs, simplifying the MCU pin budget. The -40 to +85 C range ensures stable operation inside warm amplifier chassis. Optional external PWM brightness control can be added via a digital potentiometer on VDD.
Recommended
Instrument Cluster Readouts (Bench Multimeters, Lab PSUs)
Bench instruments such as programmable lab power supplies show precise 6-digit voltage/current readouts and frequently include 4 front-panel keys. The STLED316SMTR drives the 6-digit display and scans the keys in a single IC, freeing the main measurement DSP/MCU to focus on ADC acquisition and control loops. Its 5 V supply is compatible with most bench-instrument rails, and the 24-pin SO package fits even the most compact 1/4-rack housings. Pair with a 24-bit ADC for full 6.5-digit bench-DMM accuracy.
Recommended
Status / Counter Panels (Production Line Counters, Timers)
Production-line counters and event timers often need a 6-digit count plus 4 function keys (Reset, Start, Stop, Mode). The STLED316SMTR combines the display driver and keypad interface in one SO-24 chip, dramatically simplifying the panel BOM. Its low standby current is ideal for battery-backed counters that retain count during mains interruptions. Multiple STLED316SMTRs can be cascaded on the same 3-wire SPI bus by using independent STB (strobe) lines to address each panel separately.
Recommended
Recommended Products Summary
Engineering reference data for STLED316SMTR — comparison, design guidance, and compliance information.
Selection Guide
Comparison with Alternatives
| Parameter | This Product | STLED316S | STLED316M | TM1637 | TM1638 |
|---|---|---|---|---|---|
| Brand | STMicroelectronics | STMicroelectronics | STMicroelectronics | Titan Micro Electronics | Titan Micro Electronics |
| Package | SO-24 | SO-24 | SO-24 | SO-24 | SO-28 |
| Number of Digits | 6 | 6 | 6 | 6 | 10 |
| Number of Segments | 8 (7-seg + DP) | 8 | 8 | 8 | 10 |
| Segment Output Current | 40 mA | 40 mA | 35 mA | 40 mA | 40 mA |
| Serial Interface | 3-wire SPI | 3-wire SPI | 3-wire SPI | 2-wire proprietary | 2-wire proprietary |
| Key-Scan Matrix | 2 x 2 (4 keys) | 2 x 2 | 2 x 2 | 2 x 1 (2 keys) | 3 x 8 (24 keys) |
| Supply Voltage | 4.5 V to 5.5 V | 4.5 V to 5.5 V | 4.5 V to 5.5 V | 3.3 V to 5.5 V | 3.3 V to 5.5 V |
| Operating Temperature | -40 C to +85 C | -40 C to +85 C | -40 C to +85 C | -40 C to +85 C | -40 C to +85 C |
Key Differentiators
- True 4-key scanning with hardware debounce (vs TM1637)
- Industry-standard 3-wire SPI-compatible interface (vs TM1637)
- STMicroelectronics industrial-grade -40 to +85 C qualification (vs TM1638)
Design Notes
Place a 100 nF ceramic decoupling capacitor as close as possible to the VDD pin (pin 23) and a 10 uF bulk capacitor within 5 mm. Keep the 3-wire SPI traces (CLK, DIN, STB) short and routed away from the segment/digit outputs to avoid capacitive coupling that may inject display noise into the serial data. The TEST pin (pin 24) should be tied to GND or left open in production - never drive it high.
Estimated: at full 6-digit multiplex with all segments ON and 40 mA per segment, the worst-case instantaneous supply current can reach 8 x 40 mA x 6 / 6 (duty) = 320 mA peak. Select a 5 V regulator rated for at least 500 mA to avoid dropout during digit transitions. The average current is much lower (~50-80 mA) due to multiplexing duty cycle, but the peak demand dictates regulator sizing.
Do not exceed the 40 mA per-segment absolute maximum - sustained overcurrent will degrade the open-drain output FETs. Always use a current-setting resistor (RSET) if LED forward voltage is below 3 V to limit inrush. For common-anode displays, ensure the digit commons are switched appropriately; STLED316SMTR drives commons as open-drain so they must be pulled up externally for common-anode topology.
The 3-wire SPI interface is SPI-mode-0 compatible (CPOL=0, CPHA=0). Maximum clock rate per the datasheet is typically 1 MHz - exceeding this can corrupt display data. For long PCB traces (>50 mm) add a 33 ohm series resistor on CLK to dampen reflections. When cascading multiple STLED316SMTRs, give each device a unique STB line; CLK and DIN can be shared.
Compliance Information
RoHS compliant per STMicroelectronics product page. Not AEC-Q100 qualified - this is an industrial/consumer-grade part. Halogen-free per ST green-compliance statement.
