Analog Devices Inc. LTC1515CS8#PBF

Overview

LTC1515CS8#PBF from Analog Devices (formerly Linear Technology) is a micropower switched capacitor DC/DC converter supporting step-up or step-down voltage conversion with programmable 3.3V/5V output, ±4% regulation over 2V–10V input, 650kHz switching frequency, and integrated open-drain power-on reset (POR) for GSM SIM interface power management.

For engineers reviewing the LTC1515CS8#PBF datasheet, LTC1515CS8#PBF pinout, LTC1515CS8#PBF application, or LTC1515CS8#PBF equivalent, key selection criteria include input voltage range compatibility (2V–10V), dual-output voltage selection (3.3V/5V via logic pin), soft-start inrush control, shutdown current <1µA, and SO-8 package thermal performance (θ_JA = 110°C/W).

Technical Context

The LTC1515CS8#PBF implements a dual-mode charge pump architecture that automatically switches between step-up (voltage doubler) and step-down (gated switch) operation based on VIN–VOUT differential sensing. Internal voltage-controlled output impedance adjustment prevents excessive inrush current during high-differential transitions.

Regulation is achieved via a hysteresis-based comparator comparing FB voltage to a 1.232V internal reference; POR activation requires VOUT to remain within ±6.5% of target for ≥200ms (typ). The 5/3 pin selects output voltage (3.3V or 5V) using internal resistor networks-no external divider required.

Key Specifications

Pinout & Package

Package: 8-lead plastic SO (SO-8, narrow 0.150"), θ_JA = 110°C/W, TJ_MAX = 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 LTC1515IS8-3.3/5, the LTC1515CS8#PBF offers identical electrical performance but reduced thermal operating range; compared with LTC1516CS8, it provides dual-voltage selection and 2.5× higher output current at lower quiescent current - making it superior for SIM and smart card applications demanding flexibility and efficiency.

Availability

LTC1515CS8#PBF is available at Aetrix Electronics and suitable for GSM SIM interface power, smart card reader supply, and portable equipment local supply requiring stable component supply, long-term lifecycle support, and traceable sourcing.

Supply support for LTC1515CS8#PBF 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 pioneered high-performance switched-capacitor DC/DC converters for space-constrained, low-power applications.

The LTC1515 series was designed specifically for dual-voltage SIM and smart card power delivery in cellular handsets and portable devices, emphasizing micropower operation, automatic topology selection, and integrated POR functionality.

FAQ

What output voltages does the LTC1515CS8#PBF support, and how are they selected?

The LTC1515CS8#PBF supports programmable 3.3V or 5V output. Selection is controlled by the logic state of the 5/3 pin (Pin 3): a logic high sets VOUT to 5V, and a logic low sets VOUT to 3.3V. This is implemented using internal resistor networks - no external feedback components are required. The LTC1515CS8#PBF does not support adjustable output voltages; that function is reserved for the base LTC1515 variant (which uses FB pin and external divider).

Does the LTC1515CS8#PBF require external capacitors, and what values are recommended?

Yes, the LTC1515CS8#PBF requires three external capacitors: a 0.22µF ceramic flying capacitor (C1) between C1+ and C1–, a ≥10µF low-ESR input capacitor (CIN) from VIN to GND, and a ≥10µF low-ESR output capacitor (COUT) from VOUT to GND. For VIN ≥8V, COUT should be increased to 22µF or greater to maintain output ripple ≤100mV_P-P. All capacitors must be placed close to their respective pins for optimal noise and transient performance.

How does the power-on reset (POR) function work on the LTC1515CS8#PBF?

The POR pin (Pin 2) is an open-drain output that pulls low during initial power-up, shutdown, or whenever VOUT deviates more than ±6.5% from its regulated value. Once VOUT stabilizes within that window, an internal timer starts and releases POR after 200ms (typ). An external pull-up resistor (typically to VOUT) is required. This behavior ensures downstream logic receives a clean, delayed reset signal only after stable power is confirmed - a critical feature for reliable GSM SIM initialization in the LTC1515CS8#PBF.

What protection features are built into the LTC1515CS8#PBF?

The LTC1515CS8#PBF includes short-circuit protection (limits IOUT to 12–40mA when VOUT < 100mV), overtemperature shutdown (activates at ~150°C, resumes at ~140°C), and inrush current limiting via soft-start and adaptive output impedance control. It tolerates indefinite VOUT short-to-GND and features shutdown disconnect that isolates the load from VIN. These protections ensure robust operation in portable and SIM-card applications where fault conditions are common - all without external components.

Can the LTC1515CS8#PBF operate from a 2.5V input and deliver 5V at 50mA?

No. While the LTC1515CS8#PBF accepts inputs as low as 2V, its 5V output mode requires VIN ≥ 2.7V (per Electrical Characteristics table). At VIN = 2.5V, the device cannot sustain 5V output at full 50mA load - regulation will fail. For 5V output, minimum input is 2.7V (at ≤15mA load) or 3.3V (at ≤50mA load). The LTC1515CS8#PBF can deliver 3.3V down to VIN = 2.0V, making it suitable for ultra-low-voltage 3.3V applications.