Analog Devices Inc. LTC3552EDHC-1#PBF

Overview

LTC3552EDHC-1#PBF from Analog Devices (formerly Linear Technology) is a standalone linear Li-ion battery charger with integrated dual synchronous buck converters for portable electronics. It delivers up to 950mA charge current at 4.2V ±1% float voltage, and provides fixed 1.8V/800mA and 1.575V/400mA DC/DC outputs. Designed for USB-powered devices, it requires no external sense resistor, blocking diode, or MOSFET.

For engineers reviewing the LTC3552EDHC-1#PBF datasheet, LTC3552EDHC-1#PBF pinout, LTC3552EDHC-1#PBF application, or LTC3552EDHC-1#PBF equivalent, key selection considerations include thermal regulation behavior, C/5 charge termination programmability, dual-regulator burst-mode efficiency at light loads, and DFN-16 (5mm × 3mm) package integration for space-constrained handhelds.

Technical Context

The LTC3552EDHC-1#PBF integrates two functionally independent subsystems: a linear charger with internal P-channel power FET and thermal foldback limiting at ~120°C, and two current-mode synchronous buck regulators sharing a 2.25MHz oscillator and operating in-phase. Each regulator uses internal resistive feedback dividers (1.8V and 1.575V outputs referenced to 0.6V), eliminating external resistors.

Charge control employs constant-current/constant-voltage regulation with programmable termination via ITERM pin (100mA or 20mA thresholds), automatic recharge at ~4.10V, and soft-start (100µs ramp). Regulators support individual RUN pin enable/disable, Burst Mode operation below ~10mA load, and dropout operation with 100% duty cycle when VCC approaches output voltage.

Key Specifications

Pinout & Package

Package: 16-lead DFN (5mm × 3mm × 0.75mm) with exposed ground pad (Pin 17) requiring PCB soldering for thermal performance (θJA = 40°C/W).

Key Features

Applications

Equivalent & Alternatives

The following parts are listed as comparable options for similar dual-output battery charger applications.

Compared with BQ24190RGER and MAX1555ETA+, the LTC3552EDHC-1#PBF uniquely combines linear charging safety, dual fixed low-noise buck outputs, and analog charge monitoring in one DFN package - ideal for USB-powered portable designs where simplicity, reliability, and minimal external components are prioritized over programmability or ultra-high efficiency.

Availability

LTC3552EDHC-1#PBF is available at Aetrix Electronics and suitable for smartphone baseband power, Bluetooth headset core supply, portable medical monitors, and USB-powered IoT sensor hubs requiring stable component supply and long-term manufacturability.

Supply support for LTC3552EDHC-1#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) is a global leader in high-performance analog, mixed-signal, and power management semiconductors.

The LTC3552-1 belongs to Linear's Power Management family, designed specifically for highly integrated, space-constrained portable electronics requiring combined battery charging and multi-rail DC/DC conversion without external passive components.

FAQ

What is the maximum charge current supported by the LTC3552EDHC-1#PBF?

The LTC3552EDHC-1#PBF supports up to 950mA charge current when configured with RPROG = 2kΩ and implemented on a thermally optimized PCB. This value assumes ambient temperature ≤25°C and proper soldering of the exposed pad. At higher temperatures or with reduced copper area, thermal regulation will automatically reduce current to maintain ~120°C junction temperature - the LTC3552EDHC-1#PBF does not require external thermal sensors to enforce this limit.

Does the LTC3552EDHC-1#PBF require external resistors to set its buck output voltages?

No, the LTC3552EDHC-1#PBF does not require external resistors to set its buck output voltages. The 1.8V and 1.575V outputs are internally generated using factory-trimmed resistive dividers (240k/120k for VOUT1, 195k/120k for VOUT2), both referenced to a 0.6V internal bandgap. This eliminates layout sensitivity, improves accuracy (±1.5% over temperature), and reduces bill-of-materials - the LTC3552EDHC-1#PBF achieves fixed outputs with zero external feedback components.

How does the LTC3552EDHC-1#PBF handle battery recharge after termination?

The LTC3552EDHC-1#PBF performs automatic recharge when the battery voltage drops to ~4.10V (approximately 100mV below the 4.2V float voltage), with a 2ms comparator filter time (tRECHRG) to prevent false triggers from noise. During recharge, the CHRG pin resumes pull-down state, signaling active charging. If no battery is present, the LTC3552EDHC-1#PBF cycles between termination and recharge, generating a sawtooth waveform at BAT - this behavior is intrinsic to the LTC3552EDHC-1#PBF's analog control architecture and requires no external circuitry.

Can the LTC3552EDHC-1#PBF operate from a standard USB 2.0 port?

Yes, the LTC3552EDHC-1#PBF is explicitly designed to operate from a standard USB 2.0 port (5V ±5%). Its VIN range (4.25V–8V), UVLO threshold (3.8V), and ability to deliver up to 950mA make it compliant with USB Battery Charging v1.2 specifications. The LTC3552EDHC-1#PBF draws <50µA in shutdown and <2µA in sleep mode when VIN is removed - meeting USB suspend current requirements without additional circuitry.

What is the purpose of the PROG pin on the LTC3552EDHC-1#PBF beyond charge current programming?

Beyond setting charge current via RPROG, the PROG pin on the LTC3552EDHC-1#PBF serves as an analog current monitor: VPROG × 1000 = IBAT (in mA). This enables real-time battery fuel gauging without external sense resistors or amplifiers. The pin is clamped at ~2.4V and operates across all modes (CC, CV, standby), making the LTC3552EDHC-1#PBF suitable for systems requiring battery health diagnostics - the PROG pin's dual role is a key differentiator of the LTC3552EDHC-1#PBF versus simpler charger ICs.