Texas Instruments TL7660CP

Overview

TL7660CP from Texas Instruments is a CMOS switched-capacitor voltage converter that performs positive-to-negative supply conversion with no external diodes required. It operates from 1.5 V to 10 V input, delivers –1.5 V to –10 V output, achieves 99.9% open-circuit voltage conversion efficiency, and supports oscillator frequency adjustment via the OSC pin. It is used in portable electronics for generating clean negative rails from single-supply systems.

For engineers reviewing the TL7660CP datasheet, TL7660CP pinout, TL7660CP application, or TL7660CP equivalent, key selection criteria include its 8-pin PDIP package, LV pin control logic for low-voltage operation, dual-mode capability (negative converter or voltage doubler), and latchup-immune substrate biasing architecture.

Technical Context

The TL7660CP integrates an RC oscillator (nominal 10 kHz at VCC = 5 V), linear regulator, voltage-level translator, and four power MOS switches (one p-channel, three n-channel) in a latchup-protected topology. Its logic network dynamically biases switch substrates based on VOUT sensing to maintain reverse-biased junctions across temperature and load.

Operation requires only two noncritical external capacitors: one for charge pumping (CAP+ and CAP−), one for reservoir (VOUT to GND). The LV pin enables bypass of the internal series regulator below 3.5 V input, while floating LV above 3.5 V ensures safe anti-latchup operation.

Key Specifications

Pinout & Package

TL7660CP is housed in an 8-pin plastic dual in-line package (PDIP), with 0.3-inch body width and standard through-hole mounting. Pin 1 is located at the top-left corner when viewed from the top with notch or dot orientation.

Key Features

Applications

Equivalent & Alternatives

The following parts are listed as comparable options for similar switched-capacitor voltage converter applications.

Compared with MAX1044CPA+ and ICL7660SIPAZ, TL7660CP offers superior low-voltage efficiency via LV pin control and lower typical supply current, but requires careful OSC/LV pin configuration to avoid latchup-making it ideal for cost-sensitive, battery-operated systems where layout simplicity and IQ are critical.

Availability

TL7660CP is available at Aetrix Electronics and suitable for portable instrumentation power, data acquisition signal conditioning, RS-232 transceiver bias, and split-rail audio amplifier supply requiring stable component supply across extended temperature ranges.

Supply support for TL7660CP 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 company headquartered in Dallas, Texas, delivering analog and embedded processing solutions for industrial, automotive, and personal electronics markets.

The TL7660CP belongs to TI's legacy CMOS voltage converter product line, designed specifically for low-noise, inductorless negative rail generation in space- and cost-constrained applications where reliability and minimal external components are essential.

FAQ

What is the correct LV pin configuration for TL7660CP when operating from a 3.3 V supply?

For TL7660CP operating from 3.3 V, the LV pin must be tied directly to GND. This bypasses the internal series regulator, reducing dropout voltage and quiescent current-enabling stable operation down to 1.5 V input. Leaving LV floating at 3.3 V risks latchup due to insufficient regulator headroom.

Can TL7660CP generate a positive doubled output voltage, and what external components are required?

Yes, TL7660CP can operate as a voltage doubler by adding two external diodes and reconfiguring the capacitor connections per Figure 9 in the datasheet. D1 and D2 must be low-VF Schottky diodes (e.g., BAT54), and C1/C2 values should be ≥10 µF. Output becomes approximately (2×VCC) – (2×VF), with VF dependent on diode selection and load current.

What is the maximum continuous output current supported by TL7660CP at 5 V input and 25°C ambient?

TL7660CP supports up to 20 mA continuous output current at VCC = 5 V and TA = 25°C, with typical output source resistance of 45 Ω. At higher currents or elevated temperatures, output voltage droop increases significantly-designs requiring >15 mA should verify ROUT vs. temperature curves and consider paralleling multiple TL7660CP units.

Why does TL7660CP require the VOUT pin to never exceed GND potential, and how is this enforced in practice?

TL7660CP will latch up if VOUT rises above GND due to forward-biasing internal substrate junctions. To enforce this, a 1N914 or BAT54 diode must be placed between VOUT (anode) and GND (cathode). This clamps VOUT ≤ –0.3 V, preventing destructive latchup during transient conditions like load dump or hot-plug events.

How does changing the capacitor value on the OSC pin affect TL7660CP performance, and what is the recommended range?

Adding capacitance to the OSC pin linearly reduces oscillator frequency: 100 pF lowers fOSC from 10 kHz to ~1 kHz. Lower fOSC reduces switching losses but increases output impedance unless C1/C2 are scaled proportionally (e.g., 100 pF → 100 µF C1/C2). Recommended OSC capacitor range is 0–1000 pF; beyond 1000 pF, startup time and regulation degrade.