NSD5604 / NSD5604N Four-Channel Low-Side Driver IC

In industrial automation, switching control of loads such as PLC digital outputs, relay coils, solenoid valves, and solenoids is an extremely common requirement. Traditional discrete solutions usually need to be paired with multiple devices such as power MOSFETs, freewheeling diodes, and auxiliary power supplies. This not only creates long BOM lists and large PCB areas, but voltage spikes when inductive loads turn off and reliability issues caused by complex on-site electromagnetic environments also increase debugging and maintenance costs.

The NSD5604/NSD5604N is an industrial-grade four-channel low-side driver IC from NOVOSENSE. It integrates power switches, freewheeling clamps, hardware protection, and an auxiliary power supply in an HTSSOP16 package, and can replace multi-device discrete solutions, simplifying system design and improving mass-production reliability.

1. Product Parameters and Model Differentiation

The NSD5604/NSD5604N is a 4-channel low-side driver designed specifically for industrial applications. The device has four parallel input interfaces and can independently control four driver outputs to handle resistive, inductive, or capacitive loads. The two models have identical driver cores and protection mechanisms, differing only in the integrated auxiliary power supply:

• NSD5604：It integrates a 5V/20mA LDO regulator that can directly power nearby digital isolators and optocouplers, eliminating the need for an external standalone LDO IC. It is suitable for scenarios such as PLC isolated outputs and relay driving with optocouplers;
• NSD5604N：It has no integrated LDO, offers a cost advantage, and is suitable for systems that already have an auxiliary power supply.

Additional note:NOVOSENSE also offers an automotive-grade version of the NSD5604—the NSD5604N-Q1HTSPR.

Parameter overview

Functional Block Diagram

2. Key Features

1Drive Capability and Channel Flexibility

NSD5604 integrates four independently controllable low-side power switches, enabling switch control of four loads with a single chip and reducing the number of discrete components. At 25°C, each channel can support 2 A continuous output current; when all four channels operate simultaneously, each channel can still provide 1 A, meeting the requirements of most industrial digital outputs and relay drives. If a single load requires higher current, the chip also supports parallel operation of multiple channels to flexibly increase load-driving capability.

The four channels support independent PWM input control, with a maximum frequency of up to 200 kHz and a typical input-to-output propagation delay of 0.5 μs, making them suitable for low-precision speed control, dimming, and other scenarios requiring PWM regulation. The logic inputs are compatible with 3.3 V and 5 V levels and include built-in 100 kΩ pull-down resistors, allowing direct connection to mainstream MCUs and DSPs without additional level shifting while preventing false outputs at power-up.

2Inductive Load Freewheeling Management

In industrial scenarios, relays, solenoid valves, stepper motors, etc., are mostly inductive loads. Improper handling of inductive freewheeling spikes at turn-off can easily break down power devices and also cause EMI over-limit issues.

Each output of the NSD5604 has a built-in freewheeling diode and provides a configurable freewheeling scheme through the common Vz pin:

• Slow decay mode:Connect the Vz pin directly to the power supply VM. During turn-off, the inductor current freewheels to the power supply through the internal diode. The turn-off process is smooth, voltage spikes are low, and EMI performance is better. This mode is suitable for ordinary relays, contactors, and other scenarios that do not require high turn-off speed and pursue low noise.
• Fast decay mode:Connect the Vz pin to ground through an external TVS or Zener diode. This can significantly increase the turn-off speed of inductive loads, meeting the requirements of scenarios such as solenoid valves and high-speed solenoids that have response-time requirements. In conjunction with the on-chip active clamp circuit, the turn-off spike can be clamped at a typical 58 V, protecting the power stage from overvoltage stress.

The two modes can be configured flexibly, allowing the same chip to adapt to industrial loads with different characteristics and improving the versatility of the solution.

3Multiple Hardware Protections

Industrial site environments are complex. Load short circuits, voltage fluctuations, and high-temperature conditions can all affect device lifetime. A comprehensive protection mechanism is the core guarantee of mass-production reliability. The entire NSD5604 series integrates multiple hardware protections; all protection actions are performed automatically by the chip, reducing the complexity of control logic:

• Overcurrent Protection (OCP): Each output is independently monitored, with a typical current threshold of 3 A and 3.5 μs debounce time to prevent false triggering caused by startup inrush or interference. When overcurrent is triggered, the corresponding channel automatically shuts down and automatically retries after 1.2 ms (typical). A fault on a single channel does not affect normal operation of the other three channels, improving system fault tolerance.
• Dual Overtemperature Protection: A dual architecture of “independent per-channel temperature sensing + chip-wide global temperature sensing” is used. Channel overtemperature shuts down only the corresponding faulty channel, while global overtemperature shuts down all outputs and the LDO. The trip threshold is typically 160°C with 20°C hysteresis; operation automatically resumes after the temperature falls back to a safe range, balancing protection accuracy and system availability.
• Undervoltage Lockout (UVLO): When the supply VM drops below 7 V (typical), the chip forces all outputs off to prevent the power transistors from operating in the linear region at low voltage and causing overheating damage. Operation automatically resumes after the voltage recovers, adapting to power-supply fluctuations in industrial environments.
• Fault Status Reporting: An open-drain nFAULT pin is built in. When overcurrent, overtemperature, or undervoltage faults are triggered, the pin is pulled low and can connect directly to the host MCU for system-level fault diagnosis and alarms, facilitating equipment maintenance.

4Package and Thermal Design

The NSD5604 series uses an HTSSOP16 package with a bottom thermal pad, measuring 4.96 mm × 6.4 mm, and has an operating ambient temperature range of -40°C to 125°C, offering advantages in compact industrial modules. The chip has an exposed thermal pad on the bottom. In terms of thermal resistance, the junction-to-ambient thermal resistance is typically 39°C/W with a 4-layer PCB design (50°C/W with a 2-layer PCB). Together with comprehensive thermal protection mechanisms, it can maintain stable operation in multi-channel, high-current scenarios.

Pin and Package View

III. Application Scenarios and Competitor Snapshot

The NSD5604 targets the industrial low-side driver market and can cover the following typical scenarios:

• Industrial PLC digital output modules;
• Intermediate relay and contactor coil drive;
• Control of industrial solenoid valves and pneumatic solenoids;
• Unipolar stepper motor drive;
• Intelligent switching control of resistive and inductive loads in industrial equipment.

The key parameters of similar 4-channel low-side driver solutions are listed below:

Compared with some similar competing products on the market, its performance is at a mainstream level. Combined with the inherent cost and supply advantages of an integrated LDO and domestic chips, the overall solution is more competitive in cost-effectiveness.

IV. Conclusion

Overall, the NSD5604/NSD5604N is a highly integrated single-chip solution that solves the pain points of discrete designs: many components, complex debugging, and limited reliability. Four independent channels, configurable inductive-load freewheeling, and automatic full-chain hardware protection balance cost, size, and reliability. It is a cost-effective low-side load driver for industrial automation. Novosense's support and stable supply chain enable rapid implementation and mass production.

For more information about the NSD5604 or to request samples, please contact: sales@chiplinkstech.com; Mr. Chen, 13924675549.

Appendix: Sample Request

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