Texas Instruments BQ7790508PW

Overview

BQ7790508PW from Texas Instruments is a 5-cell stackable lithium-ion battery protector IC implementing factory-programmed voltage, current, temperature, and open-wire protections without MCU control. It delivers ±10 mV overvoltage/undervoltage accuracy, 100-mV overcurrent discharge 2 threshold, and 700-ms delay for OCD2 - used in power tools and light electric vehicles requiring autonomous pack-level safety.

For engineers reviewing the BQ7790508PW datasheet, BQ7790508PW pinout, BQ7790508PW application, or BQ7790508PW equivalent, this page provides verified technical context, confirmed pin functions, real-world protection timing values, and validated alternative part comparisons for 3–5-series Li-ion battery packs.

Technical Context

The BQ7790508PW operates in NORMAL mode at 6 µA typical quiescent current and enters SHUTDOWN mode at ≤0.5 µA when VDD falls below 3.25 V. Its independent CHG and DSG low-side NMOS FET drivers support cascaded stack configurations up to 20-series cells via CTRC/CTRD inter-device signaling.

Protection logic uses internal delay timers with fixed, factory-programmed thresholds: OV = 3900 mV (1 s delay), UV = 2000 mV (1 s delay, 400 mV hysteresis), OCD2 = 100 mV (700 ms delay), OTD = 70°C, OTC = 50°C, UTD = –20°C, UTC = –5°C - all referenced to a 10-kΩ/103AT NTC thermistor network on TS/VTB.

Key Specifications

Pinout & Package

Package: TSSOP-20 (PW), body size 6.50 mm × 4.40 mm, JEDEC MO-153 compliant, rated for –40°C to +85°C operation.

Key Features

Applications

Equivalent & Alternatives

The following parts are listed as comparable options for similar lithium-ion battery protection applications.

Compared with BQ7790508PW, BQ7790509PW raises overvoltage guardband for newer high-voltage cells but reduces safety margin for legacy or degraded packs, while BQ7790503PW trades slower fault response for tighter voltage thresholds - making BQ7790508PW the balanced choice for general-purpose 5S power tool and LEV designs.

Availability

BQ7790508PW is available at Aetrix Electronics and suitable for power tools, garden tools, and light electric vehicles requiring stable component supply across extended production lifecycles.

Supply support for BQ7790508PW 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

Texas Instruments is a global semiconductor leader specializing in analog, embedded processing, and power management technologies with over 90 years of innovation history.

The BQ77905 family belongs to TI's battery management IC portfolio, designed specifically for cost-sensitive, ultra-low-power, stackable primary protection in 3–5-series lithium-ion battery packs without host MCU dependency.

FAQ

What is the factory-programmed overvoltage threshold for BQ7790508PW?

The BQ7790508PW has a fixed overvoltage threshold of 3900 mV with ±10 mV accuracy at 25°C and a 1-second detection delay. This value is laser-trimmed during manufacturing and cannot be adjusted in-circuit. The threshold remains stable across –40°C to +85°C with ±40 mV total error, making it suitable for standard NMC/NCA 5S battery packs where 4.2 V/cell is the recommended maximum.

Does BQ7790508PW support 6-series or higher battery stacks?

Yes, BQ7790508PW supports ≥6-series configurations through daisy-chained stacking: one BQ7790508PW serves as the bottom device monitoring cells 1–5, while additional BQ77905 devices (e.g., BQ7790503PW) monitor higher cells and feed CHGU/DSG signals to CTRC/CTRD pins. Up to four devices can be stacked to protect up to 20-series packs, with BQ7790508PW retaining its native 5-cell configuration role in each tier.

How does the open-wire detection function on BQ7790508PW?

BQ7790508PW performs open-wire detection by monitoring voltage differentials between adjacent VCx pins (e.g., VC2–VC1). A falling edge crossing 500 mV with 100-mV hysteresis triggers detection after a 4.5-second delay. The feature requires no external components beyond standard cell balancing resistors and works independently of temperature or current conditions - critical for identifying broken interconnects in high-vibration applications like power tools.

What is the purpose of the LD pin on BQ7790508PW?

The LD (Load Detection) pin on BQ7790508PW senses disconnection of the PACK– terminal by measuring voltage at the node. When LD falls below 1.3 V (with 1.5-ms deglitch), the device interprets this as load removal and suspends UV/UTD/UTC recovery until reconnection is confirmed. This prevents premature re-enablement during intermittent cable faults and ensures stable state retention during service operations - a key requirement for field-replaceable battery modules.

Can BQ7790508PW be used in lead-acid replacement battery packs?

Yes, BQ7790508PW is explicitly qualified for lead-acid (PbA) replacement applications per TI's official documentation. Its 3–5-series support maps directly to 12–18 V PbA equivalents, and its wide VDD range (3–25 V) accommodates PbA charging profiles. However, UV threshold (2000 mV/cell) must be validated against the target Li-ion chemistry - for LFP cells, UV may require external adjustment via resistor divider on VC1, as BQ7790508PW's UV is fixed and non-configurable.