Product category:
Power Supply ICs and Controllers
News Release from: Torex Semiconductor | Subject: XCS921A18CxR and XCS621B27xR
Edited by the Electronicstalk Editorial
Team on 13 February 2004
Power chips join Bluetooth reference
designs
Cambridge Silicon Radio (CSR) has qualified two of Torex Semiconductor's new power management ICs for use in its latest Bluetooth headset reference designs.
Cambridge Silicon Radio (CSR) has qualified two of Torex Semiconductor's new power management ICs for use in its latest Bluetooth headset reference designs Both devices have been specifically developed for use with CSR's BlueCore 2
This article was originally published on Electronicstalk on 30 Apr 2008 at 8.00am (UK)
Related stories
Step-up convertors raise voltages efficiently
The XC9128/29 series from Torex deliver efficiencies up to 93% over the entire load range, and can supply 500mA to a 3.3V load from a 1.8V battery supply.
Frugal detectors are accurate about voltage
Compact voltage detectors are well suited for monitoring battery, power-supply and regulated system voltages.
The XCS921A18CxR, a synchronous step-down DC/DC convertor, provides an extremely stable 1.8V output for powering BlueCore 2, and the XCS621B27xR is a low noise LDO voltage regulator used to bias the microphone within the headset design.
The highly efficient XCS921A18CxR provides a stable output voltage with excellent dynamic performance using fewer external components than competing solutions.
The XCS921A18CxR's has a synchronous topology, with built-in N-channel switching transistor and P-channel driver transistor.
Further reading
Device provides an extra voltage regulator
XC6415 devices are ideal for portable applications where space is at a premium such as mobile phones, portable games, cameras, portable AV equipment and PDAs.
Regulators consume only 0.8uA in normal operation
Ultrasmall LDOs are ideal for portable applications where space is at a premium, such as mobile phones, portable games, cameras, portable AV equipment and PDAs.
LDOs tolerate 28V inputs
CMOS LDO regulators are ideally suited to industrial and other applications where nominal 24V supplies are commonly encountered.
The 1.2MHz switching frequency and built-in inductor current measurement permits a smaller inductor value.
Smaller value inductors have lower series resistance for a given package size and smaller series resistance means better conversion efficiency.
The higher switching frequency also allows for smaller ceramic output capacitors to be used - giving a size and cost saving.
Thus the complete power circuit, comprising DC/DC convertor (in USP-6 package), two chip capacitors and a single chip inductor occupies less than 8mm2 of PCB area - an incredibly small solution.
Comments Gareth Henson, Managing Director of Torex Semiconductor Europe: "Out of the many devices tested by CSR, the XCS921A18CxR was one of only two that met the very stringent requirements of BlueCore 2 and achieved qualification.
Given that the Torex part is smaller, uses fewer external components, and offers a much more cost-effective solution, it was chosen to provide the power supply for BlueCore 2 in the CSR's headset reference design".
"There are a few major issues that need to be addressed when marrying a DC/DC convertor to an advanced RF chip", added Henson.
" You must remember that the output of a typical DC/DC convertor is more noisy than that of a linear regulator.
But with synchronous operation and clever chip design the XCS921A18CxR overcomes these issues to directly power Bluecore2 without needing any external filtering".
The XCS621B27xR is another perfect partner for BlueCore 2, guaranteeing extremely high ripple rejection (greater than 75dB at 1kHz) and excellent dynamic performance.
If ever an LDO merited the term "high speed" then few deserve it more than the XCS621B27xR with its very quick turn-on times and fast reaction to transients.
Its very low output noise of 15uV RMS makes it ideal for providing the microphone bias in a Bluetooth headset and the Torex part is currently the only one specified for CSR's reference design.
Highly integrated, the LDO includes a reference voltage source, error amplifier, driver transistor, current limiter and phase compensator on-chip.
"Using a regulator to provide the microphone bias actually gives a smaller solution than using a resistor and a large capacitor.
This reduction in size is essential for a headset.
The low dropout spec of the XCS621B27xR also allows the designer to maximise the microphone bias voltage, even in low battery conditions.
Thus optimising the signal to noise ratio of the microphone".
Both devices are available in SOT-25 (suffix MR) and chip scale USP-6B (suffix DR) packages.
The USP-6B measures 2.0 x 1.8 x 0.65mm and is ideally suited to space constrained applications like Bluetooth headsets.
• Torex Semiconductor: contact details and other news
• Email this article to a colleague
• Register for the free Electronicstalk email newsletter
• Electronicstalk Home Page
Search the Pro-Talk network of sites
