SLG7NT4198V

The SLG7NT4198V is a dedicated 1-Hz interrupt generator from Renesas’ GreenPAK CMIC (Configurable Mixed-Signal IC) product line, originally designed by Silego Technology (acquired by Renesas in 2017). It provides a low-cost, ultra-small solution for generating periodic system interrupts without requiring a crystal, external oscillator, or MCU timer resource.

The device integrates an internal precision RC oscillator and divider chain to produce a 1-Hz output signal. The 30-µA supply current makes it suitable for always-on power management circuits where the main MCU is in sleep mode and needs periodic wake-up. Compared to using an MCU’s internal RTC or an external 32-kHz crystal, the SLG7NT4198V eliminates the need for crystal startup time, BOM cost, and firmware timer management.

The pin configuration is specifically designed for server and embedded system power management. The SENSE input monitors a voltage rail, the MBL_PWRGD_MR_N input receives a power-good signal, and the NMI_GATE output can gate a non-maskable interrupt to the host CPU. The SMC_RST_N and SMC_INIT_CK outputs provide reset and clock signals to the system management controller. The EX_VREF input allows an external voltage reference for the sense comparator.

The TDFN-8 package measures just 2.0 x 2.0 mm, making it one of the smallest interrupt generator solutions available. The exposed thermal pad on the bottom provides both electrical ground connection and thermal dissipation. MSL-1 rating allows unlimited floor life before soldering.

This device is typically used in server motherboards, networking equipment, and industrial controllers where a hardware-based 1-Hz heartbeat is needed for watchdog timers, power monitoring, or system health checks independent of software execution.

**Internal Oscillator and Divider:** The SLG7NT4198V contains an on-chip RC oscillator that generates a base frequency, which is divided down through an internal counter chain to produce the 1-Hz output. The oscillator is factory-trimmed for accuracy within the specified tolerance at 3.3 V and 25°C. The 30-µA supply current includes the oscillator and all internal logic.

**Interrupt Generation:** The 1-Hz signal drives the interrupt output pin(s) with a fixed duty cycle. The NMI_GATE output can be gated by the SENSE and MBL_PWRGD_MR_N inputs, meaning the 1-Hz interrupt is only passed to the host when the monitored voltage rail and power-good signal are within specification. This provides a hardware-level watchdog — if the interrupt stops, the host knows the power rail has failed.

**Voltage Monitoring:** The SENSE input connects to an internal comparator (referenced to EX_VREF or an internal reference). When the sensed voltage drops below the threshold, the comparator output modifies the interrupt behavior or triggers the NMI_GATE to assert a non-maskable interrupt to the CPU.

**SMC Interface:** The SMC_RST_N output provides an active-low reset to the System Management Controller, while SMC_INIT_CK provides an initialization clock. These outputs are timed relative to the power-good input to ensure proper sequencing of the management controller during power-up.