Diodes Incorporated ZXSC100N8TC

Overview

ZXSC100N8TC from Diodes Incorporated is a non-synchronous PFM DC-DC controller IC designed for single-cell NiCd/NiMH battery systems, enabling step-up conversion from as low as 0.926 V input. It delivers adjustable output voltage (≥V_IN) via external resistive feedback, achieves 82% efficiency at 1 V input, and draws only 150 µA quiescent current-optimized for portable medical devices, GPS receivers, and digital cameras.

For engineers reviewing the ZXSC100N8TC datasheet, ZXSC100N8TC pinout, ZXSC100N8TC application, or ZXSC100N8TC equivalent, key selection criteria include minimum startup voltage (1.01 V), FB reference (730 mV), ISENSE threshold (25 mV), VDRIVE drive capability (5–10 mA), and SO-8 thermal performance (780 mW @ 25°C).

Technical Context

The ZXSC100N8TC implements pulse-frequency modulation with a fixed off-time monostable (1.7–3 µs) and dual-comparator regulation: Comp1 controls switching based on FB voltage vs. 730 mV reference, while Comp2 terminates conduction when ISENSE exceeds 25 mV. Its shutdown circuit activates at V_CC = 1.01 V with 80 mV hysteresis.

It operates in discontinuous conduction mode with constant pulse width and variable frequency, relying on an external NPN switching transistor and Schottky diode. Drive current is set by an external resistor between RE and V_CC, referenced to V_CC − 25 mV, and VDRIVE supplies base current up to 10 mA to the external transistor.

Key Specifications

Pinout & Package

Package: SO-8, RoHS-compliant "Green" molding compound with lead-free finish.

Key Features

Applications

Equivalent & Alternatives

The following parts are listed as comparable options for similar DC-DC controller applications.

Compared with MAX756CPA+ and TPS61099YFFR, the ZXSC100N8TC uniquely balances ultra-low startup voltage (1.01 V), user-adjustable output (≥V_IN), and SO-8 thermal capability-making it optimal for cost-sensitive, medium-power (≤2 W), single-cell NiMH/NiCd systems requiring design flexibility.

Availability

ZXSC100N8TC is available at Aetrix Electronics and suitable for portable medical devices, GPS receivers, digital cameras, and electronic toothbrushes requiring stable component supply across long-lifecycle consumer and industrial programs.

Supply support for ZXSC100N8TC 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

Diodes Incorporated is a global manufacturer of discrete semiconductors and analog ICs, specializing in high-reliability power management, signal integrity, and protection solutions for consumer, industrial, and automotive markets.

The ZXSC100 series belongs to Diodes' low-voltage DC-DC controller product line, engineered specifically for energy-constrained single-cell battery applications where startup robustness and quiescent current efficiency are critical system-level requirements.

FAQ

What is the minimum input voltage required for ZXSC100N8TC to start regulation?

The ZXSC100N8TC starts regulation at V_CC = 1.01 V (typical) with 80 mV hysteresis, and maintains full-load regulation down to 0.926 V. This enables operation from nearly exhausted NiMH cells, unlike most boost controllers requiring ≥1.8 V startup. The internal shutdown comparator triggers reliably across temperature and process variation per DS33613 Rev. 6-2.

How is output voltage adjusted on the ZXSC100N8TC?

Output voltage is set using an external resistive divider from V_OUT to GND, connected to the FB pin. With V_FB = 730 mV (±22 mV), V_OUT = 730 mV × (1 + R_A/R_B). Resistor values must ensure FB input current ≤200 nA to minimize battery drain; typical designs use R_B = 100 kΩ and scale R_A accordingly.

Can ZXSC100N8TC drive a MOSFET instead of a bipolar transistor?

No-the ZXSC100N8TC's VDRIVE output is optimized for bipolar NPN base drive (5–10 mA sink), not MOSFET gate charging. Its drive strength and voltage swing (V_CC − 0.17 V) lack the dV/dt and peak current needed for efficient MOSFET switching. The datasheet explicitly specifies NPN transistor Q1 and provides base-drive equations for bipolar devices only.

What is the role of the ISENSE pin and how is its threshold used?

The ISENSE pin monitors voltage across an external sense resistor in series with the switching transistor's emitter. At 25 mV (typical), it triggers immediate turn-off of VDRIVE to limit peak inductor current. This sets the converter's current limit and protects against short-circuit or overload conditions-critical for battery safety and thermal management in portable systems.