Texas Instruments LM3370SD-3806/NOPB

Overview

LM3370SD-3806/NOPB from Texas Instruments is a dual synchronous step-down DC-DC converter optimized for ultra-low-voltage processor power domains, delivering 600 mA per channel with I²C-controlled dynamic voltage scaling (DVS), 2 MHz fixed-frequency PWM operation, and independent 1.6 V / 1.8 V output configuration. It supports single Li-Ion or 3-cell NiMH/NiCd input (2.7 V to 5.5 V) and integrates synchronous rectification for high efficiency in space-constrained portable systems.

For engineers reviewing the LM3370SD-3806/NOPB datasheet, LM3370SD-3806/NOPB pinout, LM3370SD-3806/NOPB application, or LM3370SD-3806/NOPB equivalent, key selection considerations include its dual-buck architecture with 180° out-of-phase switching, I²C programmable VOUT1 (1.6 V) and VOUT2 (1.8 V), spread-spectrum noise reduction, and WSON-16 package thermal performance (θJA = 26°C/W).

Technical Context

The LM3370SD-3806/NOPB implements voltage-mode control with input voltage feed-forward for stable line regulation across 2.7 V–5.5 V input. Each buck channel features internal PFET/NFET synchronous switches, cycle-by-cycle current limiting (1200 mA typ.), and automatic PFM/PWM mode transition based on load current thresholds.

Its I²C interface (400 kHz max) enables real-time DVS, forced PWM mode selection, spread-spectrum activation, and POR threshold trimming. The 180° phase shift between SW1 and SW2 reduces input ripple and surge current, while soft-start and under-voltage lockout ensure controlled startup and fault protection.

Key Specifications

Pinout & Package

LM3370SD-3806/NOPB is packaged in a 16-lead WSON (4 mm × 5 mm × 0.8 mm, package code NHR0016B) with exposed thermal pad. Pin numbering follows standard counter-clockwise layout starting from top-left corner (Pin 1 = VIN2).

Key Features

Applications

Equivalent & Alternatives

The following parts are listed as comparable options for similar dual synchronous buck converter applications.

Compared with TPS62231DRYT and LM3370TL-3806/NOPB, the LM3370SD-3806/NOPB uniquely delivers factory-configured dual 1.6 V/1.8 V outputs with I²C DVS in a thermally robust WSON package - making it optimal for space-constrained, multi-rail portable systems requiring dynamic power management.

Availability

LM3370SD-3806/NOPB is available at Aetrix Electronics and suitable for baseband processor power, application processor core supply, FPGA I/O bank power, and portable medical sensor hub applications requiring stable component supply, long-term lifecycle support, and consistent parametric performance.

Supply support for LM3370SD-3806/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 leader specializing in analog, embedded processing, and power management technologies with over 50 years of innovation in high-efficiency power conversion.

The LM3370 product line was designed specifically for portable electronics requiring dynamic voltage scaling, ultra-low quiescent current, and dual-rail integration - targeting smartphones, tablets, wearables, and battery-powered industrial sensors.

FAQ

What output voltages are factory-programmed in the LM3370SD-3806/NOPB?

The LM3370SD-3806/NOPB is factory-configured for VOUT1 = 1.6 V and VOUT2 = 1.8 V. These values are set via internal laser trimming and cannot be altered post-manufacture. However, the I²C interface allows runtime adjustment within the full device range (VOUT1: 1.0–2.0 V in 50 mV steps; VOUT2: 1.8–3.3 V in 100 mV steps), provided the selected values remain within the 2.7–5.5 V input constraint.

Does the LM3370SD-3806/NOPB support true 100% duty-cycle operation?

Yes, the LM3370SD-3806/NOPB supports 100% duty-cycle operation in low-dropout mode, where the internal PFET remains fully enhanced and the NFET is off. This allows VOUT regulation down to VIN − (ILOAD × RDS(ON)_PFET), enabling stable output even when VIN approaches VOUT. For example, with 1.6 V output and 600 mA load, dropout is ~240 mV (RDS(ON)_PFET ≈ 400 mΩ), permitting operation down to ~1.84 V input.

How does the 180° out-of-phase switching in the LM3370SD-3806/NOPB improve system design?

The 180° phase offset between SW1 and SW2 reduces input capacitor RMS current by approximately 30%, allowing smaller input capacitance (e.g., single 4.7 µF ceramic per rail instead of two 10 µF units). It also lowers peak input surge current during simultaneous load transients, easing input rail stability and reducing EMI filtering requirements - critical for noise-sensitive RF sections in portable devices.

What is the purpose of the nPOR1 and nPOR2 pins on the LM3370SD-3806/NOPB?

The nPOR1 and nPOR2 pins are open-drain, active-low power-on-reset outputs that assert when their respective output voltages fall below 94% of target (1.6 V or 1.8 V). Each requires a 100 kΩ pull-up resistor. They provide hardware-level reset signaling to microcontrollers or FPGAs, enabling reliable power sequencing - for example, holding system reset until both rails stabilize before releasing processor reset.

Can the LM3370SD-3806/NOPB operate from a single 3.3 V supply?

Yes, the LM3370SD-3806/NOPB operates across 2.7 V to 5.5 V input, fully supporting 3.3 V fixed rails. With VOUT1 = 1.6 V and VOUT2 = 1.8 V, the minimum recommended input is 3.3 V (VOUT + 1 V rule applies for VOUT ≥ 1.8 V). At 3.3 V input, typical efficiency exceeds 90% at 300 mA load per channel, and thermal rise remains within spec due to the WSON package's 26°C/W θJA.