Product category:
Power Supply ICs and Controllers
News Release from: Semtech | Subject: SC801
Edited by the Electronicstalk Editorial
Team on 20 March 2002
Complete Li-ion battery charger shrinks
to one IC
Semtech's SC801 packs a feature-rich, programmable Li-ion battery-charging system into a tiny, thermally efficient package to reduce cost, design time and circuit board real estate.
Semtech's SC801 packs a feature-rich, programmable Li-ion battery-charging system into a tiny, thermally efficient package to reduce cost, design time and circuit board real estate The SC801 is designed for use in mobile phones, personal digital assistants, digital cameras, handheld computers, and other portable and battery-powered electronic products
This article was originally published on Electronicstalk on 16 Jul 2001 at 8.00am (UK)
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The SC801 works equally well as a charging system for nickel-cadmium and nickel-metal-hydride batteries or as a general-purpose programmable current source.
"Portable electronic products impose severe space and cost constraints and narrow design windows.
The lithium-ion batteries used in these products require precise charging algorithms for safe operation and long battery life", said Eddie Yeow, Director of Portable Power Management Products at Semtech.
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"The distinction of the SC801 is its ability to meet all of the above requirements with a single 4 x 4mm integrated chip".
High integration is at the core of the SC801's capacity to cut cost, space and design time of a Li-ion battery charger.
Specifically, the chip combines a controller, thermally protected power mosfet, reverse blocking diode, and a sense resistor onto a single die mounted in a 1.0mm-high, 4 x 4mm microleaded package (MLP).
To foster heat dissipation and protect surrounding components, the package, which offers an impressive 50C/W junction-to-ambient thermal resistance, features an exposed copper heatsink that makes direct contact with a printed-circuit-board pad.
Additional space savings are gained by the chip's use of small input and output filter capacitors.
Among the performance features of the SC801 is its fast-charge current of up to 1.5A.
Additionally, to avoid overheating a fully discharged battery, the SC801 automatically invokes a precharge mode, limiting charge current to 10-125mA for batteries under 2.8V, only switching to its fast charge mode after the battery voltage reaches the 2.8V threshold.
Several functional features make the SC801 easy to use in a wide range of products and designs.
For example, the SC801 accepts input voltages from 4.2 to 14V to yield a selectable output of either 4.1 or 4.2V regulated to 1% accuracy.
Also, the chip lets designers customise the charge pattern by offering programmable precharge, fast charge, and charge termination currents.
As a result, charging can be done safely over the full industrial temperature range.
The SC801 offers battery monitoring and protection features.
For instance, output flags can directly drive LEDs to indicate overvoltage fault, charge (adapter) present, and charging or end-of-charging conditions.
Also, a battery-in-place indication notes whether a battery is present and, if not, configures the SC801 to work as a conventional low dropout (LDO) voltage regulator to correctly power the system.
Other monitoring functions include Kelvin sensor inputs to monitor the voltage at the battery terminals and an output current mode monitor for direct connection to an analog-to-digital converter or microcontroller.
In this way, a microcontroller can restart the charging process in the case of a low battery voltage, inadequate charging rates, or if charging is interrupted.
The SC801 also features soft-start operation in the event of step loads or, for when a power adapter is connected, step inputs.
All charge modes are protected against overcurrent and overvoltage conditions.
To save power, a key requirement in portable electronic products, the SC801 draws just 1A in monitor and shutdown modes.
The SC801 is available now through Semtech's network of direct sales representatives and distributors.
Pricing starts at $1.67 in 1000 unit quantities.
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