Analog Devices Inc. LTC1515CS8-3.3/5#TRPBF

Overview

LTC1515CS8-3.3/5 from Analog Devices (formerly Linear Technology) is a micropower switched capacitor DC/DC converter that provides selectable 3.3V or 5V regulated output via logic-controlled step-up/step-down operation, supports 2V–10V input, delivers up to 50mA, and integrates open-drain power-on reset - used in GSM SIM interface power supplies.

For engineers reviewing the LTC1515CS8-3.3/5 datasheet, LTC1515CS8-3.3/5 pinout, LTC1515CS8-3.3/5 application, or LTC1515CS8-3.3/5 equivalent, key selection criteria include programmable dual-output voltage, ±4% regulation over wide VIN, 650kHz switching frequency, <1µA shutdown current, and SO-8 package compatibility with portable low-power systems.

Technical Context

The LTC1515CS8-3.3/5 implements a unique charge pump architecture that automatically selects step-up (voltage doubler) or step-down (gated switch) mode based on real-time VIN–VOUT differential sensing. It uses internal resistor networks and a logic-controlled 5/3 pin to select between 3.3V and 5V outputs without external feedback components.

Regulation relies on a 1.232V internal reference comparator with hysteresis, enabling burst-mode operation for high light-load efficiency. The integrated soft-start limits inrush current to ~12.5mA during VOUT ramp-up (4ms typical), while thermal and short-circuit protection ensure robustness under fault conditions.

Key Specifications

Pinout & Package

Package: 8-lead plastic SO (SO-8, narrow 0.150"), JEDEC MS-012AC, θJA = 110°C/W, TJMAX = 125°C.

Key Features

Applications

Equivalent & Alternatives

The following parts are listed as comparable options for similar switched-capacitor DC/DC converter applications.

Compared with LTC1515CS8-3/5, the LTC1515CS8-3/5 offers 3V instead of 3.3V output for legacy SIM standards, while the LTC1515IS8-3.3/5 provides identical performance with extended temperature qualification - both retain the same SO-8 package, pinout, and control interface.

Availability

LTC1515CS8-3.3/5 is available at Aetrix Electronics and suitable for GSM SIM interfaces, smart card readers, portable medical sensors, industrial local bias supplies, and battery-powered embedded systems requiring stable component supply and long-term manufacturability.

Supply support for LTC1515CS8-3.3/5 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

Analog Devices acquired Linear Technology in 2017 and maintains its precision analog and power management portfolio. Linear was founded in 1981 and specialized in high-performance linear ICs, including DC/DC converters, references, amplifiers, and data converters.

The LTC1515 series belongs to Linear's micropower switched-capacitor DC/DC converter product line, designed specifically for space-constrained, battery-sensitive applications requiring dual-voltage rail generation without inductors - targeting portable communications, smart card infrastructure, and low-power embedded systems.

FAQ

What output voltages does the LTC1515CS8-3.3/5 support, and how are they selected?

The LTC1515CS8-3.3/5 supports two regulated output voltages: 3.3V and 5V. Selection is controlled by the logic state of the 5/3 pin (Pin 3): a logic high configures VOUT to 5V, while a logic low configures it to 3.3V. This hardware-based selection eliminates external resistors and enables fast, deterministic rail switching - critical for multi-standard SIM interfaces. The LTC1515CS8-3.3/5 does not support adjustable output or 3V operation.

What is the maximum continuous output current capability of the LTC1515CS8-3.3/5?

The LTC1515CS8-3.3/5 delivers up to 50mA continuous output current at either 3.3V or 5V, verified across the full input range (3V ≤ VIN ≤ 8V for 3.3V output; 3.3V ≤ VIN ≤ 10V for 5V output). Performance remains within ±4% regulation at this load. Peak short-circuit current is limited to 12mA (typ), and thermal shutdown activates above ~150°C junction temperature to protect the device.

How does the power-on reset (POR) function work on the LTC1515CS8-3.3/5?

The POR pin (Pin 2) is an open-drain output that remains low during initial power-up, shutdown, or whenever VOUT deviates by more than 6.5% from its target. Once VOUT stabilizes within regulation, an internal timer initiates a 200ms (typ) delay before releasing POR high. An external pull-up resistor to VOUT is required. This behavior ensures deterministic system reset timing aligned with rail stability - a key requirement in GSM and smart card applications using the LTC1515CS8-3.3/5.

Can the LTC1515CS8-3.3/5 operate from a single-cell Li-ion battery?

Yes, the LTC1515CS8-3.3/5 operates across 2V–10V input, fully covering the discharge profile of a single-cell Li-ion battery (2.7V–4.2V). At 3.3V output, it delivers 50mA with VIN ≥ 3V; at 5V output, it supports 50mA with VIN ≥ 3.3V. Its 60µA typical operating current and <1µA shutdown current maximize runtime. The internal soft-start and adaptive step-up/step-down architecture prevent brown-out during deep discharge transitions.

What external components are required for basic operation of the LTC1515CS8-3.3/5?

The LTC1515CS8-3.3/5 requires only three external capacitors: a 0.22µF ceramic flying capacitor (C1) between C1+ and C1–, and ≥10µF low-ESR input (CIN) and output (COUT) capacitors - typically 10µF tantalum or ceramic. No inductors, diodes, or feedback resistors are needed. For VIN > 8V, COUT should be increased to 22µF or greater to maintain ≤100mVpp ripple. The 5/3 and SHDN pins require logic-level drive; floating is prohibited.