High-efficiency 4ch System Power Supply IC for CCD Camera Modules

ROHM Co., Ltd. has recently announced the development of the BD8676KN, a 4ch system power supply featuring an efficiency of 80% even during all-channel (4) driving. It was designed specifically to drive CCD camera modules in a variety of devices, including in-vehicle rear monitors, digital AV equipment, surveillance cameras and PC peripheral equipment.

The number of devices equipped with cameras is increasing rapidly, driving the need for camera modules. Two types of technologies are currently in use: CMOS and CCD, each with advantages and disadvantages. CCD systems enjoy high sensitivity and an excellent S/N ratio, and are primarily used in digital cameras and camcorders. Until now, CMOS sensors consumed less power and were easier to configure, making them the ideal choice for low power applications such as web cameras.

CCD sensors require a positive and negative power supply, as well as a specialized driver circuit for controlling the startup sequence of the power supply. This results in a relatively complex configuration, requiring at least 3 power supply ICs and 2 reset ICs for timing control. Integrating all of these vital components into a power supply circuit configuration has been extremely difficult due to problems related to voltage resistance and heat generation.

ROHM's BD8676KN solves these problems by integrating 4 channels into a single chip– a 2ch step-down switching regulator for DSP/video driver along with a 1ch step-up/-down voltage power supply and 1ch inverted power supply for the CCD sensor and analog front end/driver. A sequence circuit is also built in for startup control of all power supplies, rendering reset ICs – required in conventional circuits – unnecessary. This not only reduces costs, but simplifies design as well. Additional features include internal FETs and LDO regulators for low noise and synchronous operation between the inverter charge pump and step-down switching regulator circuits that increase efficiency to greater than 80% during full-ON driving while ensuring 0uA current consumption during standby.

•Main Features

• Built-in 4ch DC/DC converter : 2ch step-down switching regulator for DSPs and video drivers + 1ch step-up/-down voltage power supply + 1ch inverted power supply for CCD sensor or AFE/driver.
• Integrated power supply startup sequence reduces costs and contributes to device miniaturization.
• External reset ICs are unnecessary due to a built-in reset function.
• Compatible with a wide range of input voltages: 4.5V to 9.0V (18V max.)
• Novel configuration ensures high efficiency during full ON (4ch) drive: 80%
• 0µA standby current
• All required power MOSFETs built-in, including FETs for inverted voltage generation
• Compact VQFN36 package (6.2mm×6.2mm×0.95mm)

4ch System Power Supply IC for CCD Cameras(PDF:558KB)

•Terminology

• Inverter Charge Pump System
  A type of DC power supply circuit that transfers charge using multiple capacitors to create a negative voltage from a positive supply voltage.

• Internal Logic Sequence Function
  Complex control is required to turn on the power supplies for CCD image sensors and video drivers. When turning on the power supplies, it is necessary to activate the negative voltage after the positive power supply. This function controls both the startup and shutdown sequence of the internal power supplies.

Power Management ICs

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