Texas Instruments SM72485MM/NOPB

Overview

SM72485MM/NOPB from Texas Instruments is a 100-V, 150-mA constant on-time buck switching regulator with integrated 100-V N-channel buck switch, 2.5-V internal reference, and no loop compensation required. It operates from 6 V to 95 V input, delivers adjustable output down to 2.5 V, and supports PV panel smart junction boxes and 42-V automotive systems.

For engineers reviewing the SM72485MM/NOPB datasheet, SM72485MM/NOPB pinout, SM72485MM/NOPB application, or SM72485MM/NOPB equivalent, key selection factors include its VIN range (6–95 V), constant-frequency operation across line/load, intelligent current limit with RCL-programmable off-time, thermal shutdown at 165°C, and dual-package availability in VSSOP-8 and WSON-8.

Technical Context

The SM72485MM/NOPB implements a constant on-time control architecture where t_ON ∝ 1/V_IN, enabling stable operating frequency across 6–95 V input and varying load. Its regulation relies on comparing FB voltage to a precision 2.5-V internal reference, with overvoltage protection triggered at 2.875 V.

Current limiting uses a forced off-time generator whose duration depends on both RCL resistance and FB voltage-35 µs at short-circuit (FB = 0 V), scaling down under partial overload. The integrated N-channel buck switch features 2.2–4.6 Ω R_DS(ON), driven via bootstrap circuitry requiring a 0.01-µF BST–SW capacitor and supported by a precharge switch active for ≈150 ns during minimum off-time.

Key Specifications

Pinout & Package

SM72485MM/NOPB is packaged in an 8-pin VSSOP (3.0 mm × 3.0 mm) with exposed thermal pad connected to GND. Pin functions are validated per TI SNVS697E datasheet Rev E.

Key Features

Applications

Equivalent & Alternatives

The following parts are listed as comparable options for similar buck regulator applications.

Compared with LM5017MM/NOPB and TPS54160DGQR, the SM72485MM/NOPB uniquely combines 95-V input capability, 150-mA output, and zero-compensation operation in a thermally enhanced 3×3 mm package - making it optimal for space-constrained, high-input-voltage bias applications where simplicity and transient robustness are critical.

Availability

SM72485MM/NOPB is available at Aetrix Electronics and suitable for PV panel junction boxes, 42-V automotive subsystems, nonisolated telecom regulators, and secondary high-voltage post regulators requiring stable component supply across extended temperature and voltage ranges.

Supply support for SM72485MM/NOPB includes scheduled delivery planning, volume procurement assistance, BOM continuity management, traceable sourcing, and lifecycle availability coordination for OEM customers, industrial embedded developers, connected-device designers, and electronics production programs.

Manufacturer

Texas Instruments is a global semiconductor company headquartered in Dallas, Texas, designing and manufacturing analog, embedded processing, and digital signal processing technologies since 1930.

The SM72485MM/NOPB belongs to TI's high-voltage DC/DC regulator product line, engineered specifically for efficient, compact bias power conversion in photovoltaic, automotive, and telecommunications infrastructure where input voltages exceed 60 V.

FAQ

What is the maximum input voltage rating for the SM72485MM/NOPB?

The SM72485MM/NOPB has an absolute maximum input voltage rating of 100 V and a recommended operating range of 6 V to 95 V. This 95-V upper limit ensures reliable operation under sustained high-voltage conditions such as PV string outputs or 42-V automotive transients, while the 100-V rating accommodates short-duration transients per ISO 7637-2. The device integrates protection features including VCC undervoltage lockout and thermal shutdown to maintain safe operation within these limits.

Does the SM72485MM/NOPB require external compensation components?

No, the SM72485MM/NOPB does not require external compensation components. Its constant on-time control architecture - where on-time varies inversely with input voltage - inherently stabilizes the control loop without needing external RC networks or type-II/type-III compensators. This simplifies design, reduces bill-of-materials count, and improves immunity to layout parasitics. All stability is achieved internally, as confirmed in TI's SNVS697E datasheet Section 7.3.1.

How is output voltage programmed on the SM72485MM/NOPB?

The output voltage of the SM72485MM/NOPB is programmed using two external resistors (RFB1 and RFB2) forming a voltage divider from VOUT to GND, with the FB pin connected to their junction. The regulation equation is VOUT = 2.5 V × (RFB1 + RFB2)/RFB1, based on the device's internal 2.5-V reference. For example, using RFB1 = 1.0 kΩ and RFB2 = 3.01 kΩ yields a nominal 10-V output. FB bias current is only 100 nA, enabling high-resistance dividers to minimize quiescent current.

What package options are available for the SM72485MM/NOPB?

The SM72485MM/NOPB is offered in two surface-mount packages: the 8-pin VSSOP (DGK, 3.0 mm × 3.0 mm) and the 8-pin WSON (NGU, 4.0 mm × 4.0 mm). Both feature an exposed thermal pad that must be soldered to a PCB ground plane for optimal thermal performance. The VSSOP variant has a junction-to-ambient thermal resistance (RθJA) of 139.6°C/W, while the WSON offers improved 42.3°C/W - making WSON preferable for higher ambient or power-dense layouts. The "MM" suffix in SM72485MM/NOPB denotes the VSSOP-8 package.

Can the SM72485MM/NOPB be remotely shut down?

Yes, the SM72485MM/NOPB supports remote shutdown via the RT/SD pin. Pulling this pin to GND disables the internal buck switch and places the device in low-current shutdown mode (110–176 µA typical). No external pull-down resistor is required - direct connection suffices. During shutdown, the VCC bypass switch is also disabled regardless of VIN level. The shutdown threshold is 0.4–1.05 V (rising), with 35-mV hysteresis, ensuring noise immunity. This function is documented in Section 7.4.4 and Pin Function Table of the SNVS697E datasheet.