Monolithic Power Systems Inc. MP1522ET-LF-Z

Overview

MP1522ET-LF-Z from Monolithic Power Systems is a 25V step-up DC-DC converter with internal 0.5Ω N-channel MOSFET, operating from 2.7V–25V input and delivering up to 25V output. It uses variable-frequency constant-peak-current control, features 1.23V feedback threshold, 1µA shutdown current, and thermal/UVLO protection in SOT23-5 package. Used in compact portable devices requiring high-voltage bias generation.

For engineers reviewing the MP1522ET-LF-Z datasheet, MP1522ET-LF-Z pinout, MP1522ET-LF-Z application, or MP1522ET-LF-Z equivalent, key selection criteria include output voltage range (VIN to 25V), minimum off-time (550ns normal / 1.6µs start-up), BIAS pin flexibility (output- or input-powered), EN logic thresholds (0.8–2.0V), and thermal shutdown at 160°C.

Technical Context

The MP1522ET-LF-Z implements a variable-frequency, constant-peak-current boost architecture with 450mA current limit and 550ns minimum off-time during regulation-extended to 1.6µs at startup for glitch-free turn-on. Its internal power switch supports up to 28V drain-source voltage, enabling stable 25V output even at low VIN.

BIAS pin operation allows dual powering modes: connected to VOUT for enhanced gate drive at low input voltages (e.g., 2.7V), or to VIN for reduced quiescent current (650–750µA). Feedback regulation is fixed at 1.23V with ±10mV hysteresis and –150nA to –80nA input bias current.

Key Specifications

Pinout & Package

MP1522ET-LF-Z is housed in a JEDEC-standard SOT23-5 package (2.9mm × 1.6mm × 1.1mm), rated for –20°C to +85°C ambient operation. Thermal resistance θ_JA = 220°C/W on 1"² 1oz copper.

Key Features

Applications

Equivalent & Alternatives

The following parts are listed as comparable options for similar step-up converter applications.

Compared with TPS61040DRVR and MAX17062ETA+, MP1522ET-LF-Z uniquely supports full 2.7–25V input with BIAS-pin configurable powering-making it optimal for battery-powered devices spanning single-cell to stacked configurations while maintaining minimal quiescent current and thermal safety.

Availability

MP1522ET-LF-Z is available at Aetrix Electronics and suitable for handheld computers, digital cameras, and small LCD displays requiring stable component supply with RoHS-compliant, lead-free packaging.

Supply support for MP1522ET-LF-Z 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

Monolithic Power Systems (MPS) is a fabless semiconductor company specializing in high-performance analog and power ICs, headquartered in Kirkland, WA, with global design and support centers.

The MP1522 belongs to MPS's high-efficiency, miniature boost converter product line-designed specifically for space- and power-constrained portable electronics needing reliable high-voltage generation from low-input sources.

FAQ

What is the recommended inductor value for MP1522ET-LF-Z when VIN = 3.3V and VOUT = 20V?

For 3.3V input and 20V output, an inductor ≥4.7µH is recommended per the datasheet. The peak current limit of 450mA must be reached within ≥550ns; lower values risk exceeding current limit prematurely. Use shielded, low-DCR types (e.g., 4.7µH, 0.1Ω DCR) with saturation current >600mA to ensure stability under load transients.

Can BIAS pin be left unconnected?

No-BIAS must be connected either to VIN or VOUT. Leaving it floating risks undefined operation and potential damage. For lowest quiescent current, tie BIAS to VIN (≥3.0V); for best low-VIN regulation (e.g., 2.7V), connect BIAS to VOUT. A 0.1µF ceramic capacitor is mandatory between BIAS and GND.

Does MP1522ET-LF-Z support synchronous rectification?

No-it uses an external Schottky or fast-recovery diode (e.g., RB751) in the boost topology. The internal switch is a single N-channel MOSFET; no synchronous rectifier driver or second switch is integrated. Efficiency gains from sync rectification require external controller-level implementation.

How does the 1.6µs startup off-time improve system reliability?

The extended 1.6µs off-time during first 64 pulses prevents inrush current surges and output overshoot at power-up or wake-from-shutdown. This avoids stress on output capacitors and downstream regulators, eliminates false triggering of overvoltage protection, and ensures clean, monotonic VOUT ramp-up-critical for analog sensor biasing and flash LED timing.

Is MP1522ET-LF-Z pin-compatible with MP1522ET?

Yes-MP1522ET-LF-Z is the RoHS-compliant, tape-and-reel version of MP1522ET. Both share identical SOT23-5 pinout, electrical specifications, and thermal characteristics. The "-LF" denotes lead-free plating; "-Z" indicates tape-and-reel packaging. No layout or schematic changes are needed for migration.

What is the maximum continuous output current at VOUT = 12V and VIN = 5V?

Per Table 1 in the datasheet, maximum continuous output current is 44mA at VIN = 5V and VOUT = 12V. This assumes proper thermal management (θ_JA = 220°C/W), 4.7µH inductor, and 1µF ceramic output capacitor. Higher loads cause thermal shutdown activation above 160°C junction temperature.

Why is a feed-forward capacitor required across R2 in the feedback divider?

The 1nF–10nF capacitor across R2 improves loop stability by adding phase margin and suppressing high-frequency switching noise coupling into FB. Without it, noise-induced false regulation can cause output ripple, audible whine, or intermittent shutdown-especially in compact layouts near RF sections or motors.