Product Description
Standex Electronics SMP-21 Series MOSFET Relay; 4 PIN / SOP; SPST-NO (1 FORM A); 0 ~ 40 V; 250 mA
MOSFET Relay • Pin Count / Package Style: 4 PIN / SOP • Circuit: SPST-NO (1 FORM A) • Load Voltage DC or Peak AC: 0 ~ 40 V • Load Current Max.: 250 mA
Product Information
| Manufacturer | Standex Electronics |
| Product Category | Relay |
| Product Sub Category | MOSFET Relay |
| Series | SMP-21 Series |
| Catalog Part Number | SMP-1A21-4PT |
Specifications
| Product Attribute | Attribute Value |
|---|---|
| Pin Count / Package Style | 4 PIN / SOP |
| Circuit | SPST-NO (1 FORM A) |
| Load Voltage DC or Peak AC | 0 ~ 40 V |
| Load Current Max. | 250 mA |
| On-State Resistance Max. | 1.25 Ohms |
| Output Capacitance | 13 pF |
| Off-State Leakage | 10 nA |
| I/O Isolation Voltage Max. | 1500 V |
| Special Feature | UL Approved, RoHS Compliant |
Series Features
SMP-21 Photo-MOSFET Relay
Series DescriptionThe SMP-21 Series is a compact, solid-state Photo-MOSFET relay designed for reliable switching in space-constrained and high-performance electronic systems. Housed in a small-outline package (SOP), it supports switching up to 40 V AC or peak DC and load currents up to 250 mA, making it ideal for low- to medium-power applications.
With a typical on-resistance of just 0.9 Ω, low output capacitance (13 pF), and minimal off-state leakage current (10 nA), the SMP-21 Series ensures clean, efficient signal control. Its solid-state design eliminates contact bounce, enhances durability, and provides immunity to shock, vibration, and environmental contaminants.
This series is well-suited for controlling both low-level analog signals and higher-level loads such as LEDs, relays, solenoids, and lamps. Its high input-to-output isolation and long operational life make it a dependable choice for demanding industrial, medical, and test environments.
- Solid-state switching with no contact bounce or mechanical wear
- Low on-resistance (typ. 0.9 Ω) for efficient power handling
- Low output capacitance (13 pF) for fast, clean signal transitions
- Minimal off-state leakage (10 nA) for high signal integrity
- High input-to-output isolation for safe circuit separation
- Compact SOP package (4- or 8-pin) for space-constrained designs
- Shock and vibration resistant, impervious to dirty environments
- Stable on-resistance over time for consistent performance
- Long operational life with high reliability in solid-state form
Automated Test Equipment (ATE): Fast, reliable signal switching
Electric Vehicles: Low-power control in battery management systems
I/O Modules: Signal routing and isolation in industrial automation
Medical Equipment: Safe, low-noise switching in diagnostic devices
Sensing Equipment: Clean signal control in precision instruments
Telecommunications: Relay replacement in compact communication systems
Security Systems: Silent, reliable switching in access control and alarms