The new units offer dynamic output voltage control (DVC) through an inter-integrated circuit (I2C) interface. DVC in the buck regulator facilitates optimization across system power modes, enabling further improvement in efficiency and battery life.
They can both work with inputs of up to 5.5 volts, making them great choices for working with lithium-ion batteries or USB devices. They both target battery-powered applications needing low ripple voltage and highly efficient power supplies. According to an email from Dialog Semiconductor, the low ripple makes the devices suitable "for use with sensitive analog circuitry, such as GPS receivers used in wearables."
Both units offer multiple protection features, as well as an ability to monitor system conditions via the GPO pin.
The DA9232 is a highly efficient, low-ripple buck regulator. Battery life is improved because of the low standby current it delivers during both operation and shutdown. The device offers up to 81% efficiency at 1.8 V output, 10 μA load currents.
DA9233 block diagram. Image from the DA9232 datasheet
Otherwise similar to the DA9232, the DA9233 also features an ultra-low quiescent current low dropout (LDO) regulator. The Buck regulator features output ripple of 10mV or less.
A key feature of the DA9233 is the integration of buck regulator and LDO on the same small IC. This serves to reduce the overall system bill-of-materials and also to save precious board-space in space-constrained applications. Note the addition of an LDO control block and accompanying pinout to the otherwise identical block diagram of the DA9232.
DA9233 block diagram. Image from the DA9233 datasheet
The low quiescent current LDO can be configured as a Load Switch and provides the second supply output. The LDO’s uncommitted inputs can be connected to either the battery powering the overall system or the buck output. Connecting the input to the buck output provides the flexibility to improve the power supply rejection ratio (PSRR) at the LDO output as needed.
The DA9233 provides up to 80% efficiency at 1.8 V output, 20 μA load currents.
Both DA9232 and DA9233
For both devices, the low ripple voltage of the DA9232 exceeds the requirements for powering GPS chipsets in wearable devices.
The following specs are also shared between both the DA9232 and the DA93233:
- 2.5V - 5.5V operating range
- 750 nA total input current (buck enabled, no load)
- Output voltage 0.6 V to 1.9 V
The units are suitable for space-constrained applications, and both come in 12-pin WLCSP packages, though they differ slightly in size. The DA9232 measures 1.70 mm x 1.30 mm x 0.5 mm, while the DA9233’s dimensions are 1.65 mm x 1.25 mm x 0.5 mm.
Buck Converter and LDO Combination Devices
There are a wide variety of devices on the market that combine buck converters and LDOs. They cover a very wide variety of voltages, currents and features. Here are two examples:
The MAX15014–MAX15017 series from Maxim Integrated features input buck converters with 1 amp, 4.5V to 40V inputs and a 50mA LDO regulator.
The ADP5003 from Analog Devices allows the internal LDO and buck regulator to work together in an adaptive mode or separately in an independent mode. The device is also covered in some detail in an AAC component assessment.
What's your experience with issues with output ripple? How did you handle these issues in your designs? Let us know in the comments below.
Featured image used courtesy of Dialog Semiconductor.