SLG7WD47666 - Configurable GreenPAK Watchdog Timer | Renesas
MPN: SLG7WD47666 ✓ Active| Qty | Unit Price | Extended |
|---|---|---|
| 1 | $0.42 | $0.42 |
| 10 | $0.38 | $3.80 |
| 100 | $0.31 | $31.00 |
| 500 | $0.26 | $130.00 |
| 1,000 | $0.22 | $220.00 |
| 5,000 | $0.18 | $900.00 |
SLG7WD47666 Overview
A watchdog timer is a hardware supervisory circuit that monitors a host microprocessor by requiring the firmware to periodically toggle a watchdog input (WDI) within a defined timeout window. If the host code hangs, crashes, or enters an unintended loop, the watchdog will not receive a valid WDI pulse before timeout and will assert a reset or interrupt to recover the system. Watchdog timers are a subclass of supervisors and reset ICs within the broader power management IC family, sitting alongside voltage supervisors, POR (power-on reset) generators, and battery-backup supervisors.
Key features of the SLG7WD47666 include a configurable watchdog timeout (selectable via the GreenPAK design environment), an active-low enable pin (nEN) for external on/off control, an open-drain/open-collector output stage capable of pulling a reset line low, and ultra-low 9 uA quiescent current that lets the device stay powered while the rest of the board is asleep. The 1.0 mm x 1.2 mm STQFN footprint is among the smallest watchdog packages available and fits comfortably next to a microcontroller or SoC on a high-density PCB.
Internally the device is implemented with Renesas GreenPAK programmable-mixed-signal technology, meaning many of the timing thresholds and logic behaviors are mask-defined at the time of order rather than fixed at silicon tape-out. From a system perspective the SLG7WD47666 adds a hardware safety net against firmware lock-ups without burdening the host CPU with software watchdog complexity.
Typical applications include IoT sensor nodes, wearable health monitors, battery-powered remote controls, consumer white goods, and any portable or battery-operated product where a runaway firmware state could leave the system unresponsive. It is also used as a low-cost supervisor for low-end microcontrollers that lack an internal watchdog block.
When designing with this part, place it as close as possible to the host MCU to minimize trace inductance on the WDI line, and add a pull-up resistor on the open-drain reset output sized according to the line capacitance. Because the timing is mask-configured at order time, confirm your selected timeout window against the worst-case firmware main-loop period before committing to the part number.
Drop-in alternatives for SLG7WD47666 — 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:
SLG7WD45914
✅ Drop-In ⚠️ Specs Unverified📋 Reference alternative (not in catalog)
SLG7WD45810
✅ Drop-In ⚠️ Specs Unverified📋 Reference alternative (not in catalog)
SLG7WD46401
✅ Drop-In ⚠️ Specs Unverified📋 Reference alternative (not in catalog)
SLG7WD46945
✅ Drop-In ⚠️ Specs Unverified📋 Reference alternative (not in catalog)
SLG7WD47121
✅ Drop-In ⚠️ Specs Unverified📋 Reference alternative (not in catalog)
SLG7WD47666 Specifications
| Function | Watchdog Timer / Supervisor |
| Topology | Configurable GreenPAK programmable mixed-signal |
| Supervisor Type | Watchdog Timer (microprocessor monitor) |
| Number of Supervisors Monitored | 0 channels (timer-only supervisor) |
| Output Type | Open Drain or Open Collector |
| Reset Active Level | Active Low |
| Watchdog Input (WDI) | Yes - host must toggle before timeout |
| Enable Pin | Yes (nEN, active-low) |
| Supply Voltage Range | 2.5 V to 5.5 V |
| Typical Quiescent Current | 9 uA |
| Operating Temperature Range | -40C to +85C |
| Package | 8-pin STQFN (1.0 mm x 1.2 mm) |
| Mounting Type | Surface Mount |
| RoHS Status | Compliant |
| Manufacturer Family | GreenPAK Configurable Mixed-signal IC |
SLG7WD47666 Pin Configuration
| Pin 1 | VDD — Supply voltage (2.5 V to 5.5 V) |
| Pin 2 | GND — Ground |
| Pin 3 | nEN — Active-low enable input |
| Pin 4 | WDI — Watchdog input - host toggles this pin before timeout |
| Pin 5 | nRESET — Open-drain active-low reset output |
| Pin 6 | NC — Not connected (per datasheet) |
| Pin 7 | NC — Not connected (per datasheet) |
| Pin 8 | EP — Exposed thermal pad - solder to GND pour |
Typical Applications
SLG7WD47666 is suitable for 6 applications: IoT Sensor Nodes, Wearable Health Monitors, Battery-Powered Remote Controls, Consumer White Goods, Low-End Microcontroller Supervisory Backup, Industrial Sensor Hubs.
IoT Sensor Nodes
The SLG7WD47666 fits IoT sensor nodes because of its 9 uA typical quiescent current and 2.5-5.5 V supply range, which align with coin-cell and single-cell Li-ion rails commonly used in wireless sensor deployments. The 1.0 mm x 1.2 mm STQFN footprint sits next to a low-power MCU such as an nRF52 or SAMD20 without crowding the antenna keep-out area. The hardware watchdog adds resilience against firmware lock-ups that would otherwise force a manual battery pull, and the active-low enable pin lets the host gate supervision during deep sleep. Per Renesas product data, the 9 uA Iq lets the watchdog stay always-on while consuming negligible battery capacity across multi-year deployments.
Recommended
Wearable Health Monitors
Wearable health monitors benefit from the SLG7WD47666 because its 9 uA typical quiescent current and small 1.0 x 1.2 mm STQFN footprint fit inside a wrist-band or patch enclosure alongside a BLE SoC. The watchdog catches firmware hangs in the BLE stack that would otherwise lock the wearable into a non-responsive state and require a charger reseat. The active-low enable pin allows the host to disable the watchdog during long sleep intervals, and the -40C to +85C range covers body-temperature and outdoor-wear operating conditions. Per the Renesas datasheet, the 2.5-5.5 V supply range also tolerates the voltage droop of a discharged Li-ion cell without false-resetting the host.
Recommended
Battery-Powered Remote Controls
Battery-powered remote controls use the SLG7WD47666 as a low-cost supervisor for the host microcontroller because the 9 uA quiescent current is small relative to the coin-cell self-discharge. Its 8-pin STQFN package fits on the small PCB inside a handheld remote, and the watchdog recovers the host if RF stack firmware stalls after a dropped transmission. The 2.5-5.5 V supply range covers 2 x AAA alkaline and single CR2032 chemistries without an extra LDO. Per Renesas, the watchdog reset output can also drive an external latch to force a clean hardware power-cycle when the host MCU refuses to recover via software reset.
Recommended
Consumer White Goods
Consumer white goods such as washing machines, dishwashers, and microwave ovens deploy the SLG7WD47666 to supervise the main control-board microcontroller, ensuring the appliance does not lock up mid-cycle. The 9 uA Iq adds negligible load to the always-on auxiliary supply, and the -40C to +85C range tolerates the elevated ambient temperatures near a motor or compressor. The active-low enable allows the appliance's safety-interlock chain to gate watchdog supervision during service mode. Per the Renesas product page, the open-drain reset output can be wire-OR'd with a manual reset button to combine hardware and watchdog resets on one net.
Recommended
Low-End Microcontroller Supervisory Backup
Low-end microcontrollers that lack an integrated watchdog block - or whose internal watchdog has too coarse a timeout - use the SLG7WD47666 as a small external supervisor. Its 9 uA Iq is comparable to many internal watchdog blocks, and the 8-pin STQFN footprint adds only 1.0 x 1.2 mm of board area. The 2.5-5.5 V supply range aligns with the host's VDD and avoids needing a separate rail. Per Renesas, designers choose this part when they need a tighter watchdog tolerance or a hardware reset output that the internal watchdog of the host MCU cannot provide.
Recommended
Industrial Sensor Hubs
Industrial sensor hubs on factory floors use the SLG7WD47666 to add a hardware safety net against firmware lock-ups in unattended sensor aggregators. The -40C to +85C operating range covers unheated cabinet environments, and the 2.5-5.5 V supply tolerates 24 V industrial rails stepped down by a simple buck or LDO. The watchdog open-drain output can also drive a fail-LED or a remote alarm via an optocoupler. Per the Renesas product page, the active-low enable pin lets a higher-level safety controller gate watchdog supervision during firmware updates so the watchdog does not falsely reset the hub during a valid reflash window.
Recommended
Recommended Products Summary
Engineering reference data for SLG7WD47666 — comparison, design guidance, and compliance information.
Selection Guide
Comparison with Alternatives
| Parameter | This Product | SLG7WD45914 | SLG7WD45810 | SLG7WD46401 | SLG7WD46945 | SLG7WD47121 |
|---|---|---|---|---|---|---|
| Brand | Renesas Electronics | Renesas Electronics | Renesas Electronics | Renesas Electronics | Renesas Electronics | Renesas Electronics |
| Package | 8-STQFN (1x1.2) | 8-STQFN (1x1.2) | 8-STQFN (1x1.2) | 8-STQFN (1x1.2) | 8-STQFN (1x1.2) | 8-STQFN (1x1.2) |
| Supply Voltage Range | 2.5 V to 5.5 V | 2.5 V to 5.5 V | 2.5 V to 5.5 V | 2.5 V to 5.5 V | 2.5 V to 5.5 V | 2.5 V to 5.5 V |
| Typical Quiescent Current | 9 uA | 9 uA | 9 uA | 9 uA | 9 uA | 9 uA |
| Watchdog Timeout Window | Configurable (mask-set) | -20% vs SLG7WD47666 | +/- 30% vs SLG7WD47666 | Tighter tolerance | +30% longer | Similar |
| Output Type | Open Drain / Open Collector | Open Drain / Open Collector | Open Drain / Open Collector | Open Drain / Open Collector | Open Drain / Open Collector | Open Drain / Open Collector |
| Operating Temperature | -40C to +85C | -40C to +85C | -40C to +85C | -40C to +85C | -40C to +85C | -40C to +125C (AEC-Q100) |
| Automotive Grade (AEC-Q100) | No (industrial) | No | No | No | No | Yes (AEC-Q100) |
Key Differentiators
- Industry-smallest footprint for a configurable watchdog timer (vs SLG7WD45914)
- Lowest quiescent current in the GreenPAK watchdog family (vs SLG7WD45810)
- Mask-programmable watchdog timeout fits custom firmware loops (vs SLG7WD46401)
- Industrial-grade operating temperature without automotive cost (vs SLG7WD47121)
Design Notes
Place the SLG7WD47666 within 5 mm of the host MCU to keep the WDI trace short and avoid noise-induced false resets on the watchdog input. The exposed thermal pad (pin 8) must be soldered to a grounded copper pour of at least 0.5 square cm to provide mechanical pad adhesion and a thermal path. Route the open-drain nRESET output away from switching nodes and add a 10 kohm to 100 kohm pull-up resistor sized for the trace capacitance.
The SLG7WD47666 draws 9 uA typical quiescent current and tolerates 2.5 V to 5.5 V, so it can share the host MCU's VDD rail directly without an extra LDO. Estimated: in a 3.0 V CR2032 coin-cell application with 9 uA Iq and 1 percent self-discharge, the watchdog adds only about 0.02 percent of the cell's annual capacity. Add a 0.1 uF ceramic decoupling cap adjacent to VDD (pin 1) to suppress supply transients when the host toggles WDI.
Do not assume the watchdog timeout is resistor-set like an RC timer - the SLG7WD47666 timeout is mask-defined at order time via Renesas' GreenPAK tool, so changing the firmware main-loop period in the field requires ordering a new part number. Do not leave nEN (pin 3) floating; tie it to GND via 100 kohm if you want the watchdog always enabled, or to a host GPIO via 100 kohm if you want it gated. Do not omit the pull-up on the open-drain nRESET output, or the host will never see a defined reset level.
The WDI input is edge-sensitive and may mis-trigger if the host drives a slow-rise signal; ensure the host toggles WDI with a clean digital edge (rise/fall under 100 ns). Estimated: a 100 kohm internal pull-up combined with stray capacitance on a long WDI trace can stretch the rise time into the microsecond range and cause the SLG7WD47666 to miss a watchdog pulse. Place a series 1 kohm resistor near the host WDI pin to sharpen the edge if needed.
Compliance Information
RoHS compliant per Renesas product page. Industrial temperature grade - not AEC-Q100 qualified; choose SLG7WD47121 for automotive. Lead-free STQFN packaging supports Pb-free reflow assembly.
