NXP Semiconductors 74LV4799SD,118

Overview

74LV4799SD,118 from NXP Semiconductors (formerly Philips) is a low-voltage Si-gate CMOS battery management IC designed specifically for NiCd/NiMH charger control. It integrates a 17-stage divider, 10-stage up/down counter, precision oscillator with external RC timing, automatic power-on reset, and dual enable outputs (EN/EN) for driving bipolar transistor charge switches. It delivers time-based battery capacity calculation across charge (4–16 h), discharge (15 min–4.7 h), and self-discharge (50–100 days) phases in single- to four-cell applications.

For engineers reviewing the 74LV4799SD,118 datasheet, 74LV4799SD,118 pinout, 74LV4799SD,118 application, or 74LV4799SD,118 equivalent, this device serves as a dedicated, oscillator-based timer IC for low-current, time-controlled NiCd/NiMH charging systems - requiring no microcontroller, supporting wide supply (0.9–6 V), offering LED/MOLLI status indication, and enabling trickle charge duty-cycle control via RC/RD/RS timing networks.

Technical Context

The 74LV4799SD,118 implements battery management through synchronous, time-measurement logic: an on-chip oscillator (with ±7% tolerance) drives a 17-stage divider and 10-stage up/down counter to track charge, discharge, and self-discharge durations. Its control logic interprets PWRS (power sense, 50 Hz–100 kHz AC/DC compatible) and DIS (discharge input with 10 ms debounce) to select among five operating modes - charge, trickle charge, charge/discharge, discharge, and self-discharge - each with distinct counter direction and timing source (RC, RD, or RS).

It features dual open-drain enable outputs (EN active HIGH, EN active LOW) for direct drive of PNP/NPN transistor pairs in low-voltage (≥1-cell) chargers, integrated Schmitt-trigger inputs on PWRS and DIS, bistable power-on reset synchronized to the oscillator clock, and scan-test capability (SCAN/SCI/MOLLI/SCO) enabling readout of remaining counter value as battery energy proxy.

Key Specifications

Pinout & Package

74LV4799SD,118 is supplied in a 16-pin plastic SO package (SOT109-1), measuring 10.0 × 4.4 × 1.75 mm, with standard SOIC thermal and mechanical characteristics.

Key Features

Applications

Equivalent & Alternatives

The following parts are listed as comparable options for similar battery timer applications.

Compared with MAX713 and UC3906, the 74LV4799SD,118 uniquely combines ultra-low quiescent current (36 µA), fully programmable time-based charge/discharge/self-discharge intervals, and integrated LED/MOLLI status - making it optimal for cost-sensitive, low-power, time-driven NiCd/NiMH maintenance chargers where voltage-sensing complexity is undesirable.

Availability

74LV4799SD,118 is available at Aetrix Electronics and suitable for domestic appliance chargers, portable medical devices, and personal communication equipment requiring stable component supply across long-life consumer product cycles.

Supply support for 74LV4799SD,118 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

NXP Semiconductors, headquartered in Eindhoven, Netherlands, designs high-reliability semiconductor solutions for automotive, industrial, and consumer applications, with deep heritage in analog and mixed-signal ICs from its Philips Semiconductors origin.

The 74LV4799SD,118 belongs to NXP's legacy battery management IC portfolio, engineered specifically for time-based NiCd/NiMH charger control in cost-sensitive, low-power consumer electronics - emphasizing autonomy, minimal external components, and robust operation down to 0.9 V.

FAQ

What is the primary function of the 74LV4799SD,118 in a battery charging system?

The 74LV4799SD,118 functions as a fully autonomous, time-based battery management IC for NiCd and NiMH chemistries. It replaces microcontroller-based timing logic by integrating an on-chip oscillator, 17-stage divider, and 10-stage up/down counter to measure and control charge time (4–16 h), discharge time (15 min–4.7 h), and self-discharge time (50–100 days) using external RC, RD, and RS networks. Its core purpose is to ensure safe, optimized charging without voltage-sensing circuitry.

How does the 74LV4799SD,118 handle low-voltage startup in single-cell applications?

The 74LV4799SD,118 ensures reliable startup at voltages as low as 0.9 V using two mechanisms: (1) an automatic power-on reset (POR) with threshold of 0.25–0.65 V that synchronizes to the oscillator clock, and (2) the Vin pin (pin 4), which provides bias current to external PNP/NPN transistors before the IC achieves full functionality. This allows EN and EN outputs to begin controlling the charge switch even while VCC is rising, preventing brownout-induced latch-up.

Can the 74LV4799SD,118 be used with lithium-ion batteries?

No, the 74LV4799SD,118 is not suitable for lithium-ion batteries. Its timing-based algorithm, charge termination logic (full-count switch to trickle), and lack of voltage/temperature monitoring make it incompatible with Li-ion safety requirements. It is explicitly designed and characterized only for NiCd and NiMH chemistries, as confirmed in the Philips 1998 product specification title, features, and application sections.

What is the role of the MOLLI/SCO pin (pin 6) in normal operation versus test mode?

In normal operation, pin 6 functions as MOLLI (More-or-Less-Low Indication): an active-LOW output delivering a 4-pulse, 1-second-duration signal (50% duty) when battery discharge completes, intended to drive a buzzer. In scan test mode (SCAN = HIGH), the same pin becomes SCO (scan output), serially shifting out the 10-bit counter value - enabling readout of remaining battery energy when paired with SCI and IOSC pins per the documented 49-clock readout procedure.

How does the 74LV4799SD,118 implement trickle charge control without a microcontroller?

The 74LV4799SD,118 implements dedicated trickle charge control by alternating between RC- and RS-defined time constants in the oscillator circuit: during trickle mode, it generates four periods of RC-C1 timing followed by three periods of RS-C1 timing. This creates a fixed duty cycle (4:3 ratio) that reduces average charge current to precisely offset battery self-discharge - independent of charger type - eliminating need for software or external PWM generation.