Dialog Semi IC lowers cost and standby power in smartphones
The firm's iW1679 digital AC/DC PWM controller is the first to replace FETs with lower-cost BJTs in 5V/2A smartphone power supplies
Dialog Semiconductor has launched what it reckons is the industry's first digital pulse width modulation (PWM) controller that can easily and efficiently drive low-cost, 10W power bipolar junction transistor (BJT) switches.
The new devices are claimed to reduce the BOM cost in 5V/2A smartphone adapters and chargers.
The new iW1679 allows designers to replace field effect transistors (FETs) with lower-cost BJTs and address the market trends for lower standby power and higher light-load and active average efficiency in smartphones, media tablets and consumer electronic products. Developed by Dialog's Power Conversion Business Group (formerly iWatt Inc.), the iW1679 delivers on Dialog's goal to expand its addressable market.
The iW1679 reduces BOM costs while achieving high efficiency through the use of Dialog's adaptive multi-mode PWM/PFM control that dynamically changes the BJT switching frequency. This optimises the system to improve light-load efficiency, power consumption and EMI. The iW1679 provides high, 83% active average efficiency, maintains high efficiency at loads as light as 10%, and achieves < 30mW no-load standby power with fast standby recovery time.
This enables designers to meet or exceed emerging global energy standards, including the proposed stringent European CoC version 5, which is anticipated to require 76% active average efficiency and high light load efficiency down to 10% loads, as well as the proposed U.S. DoE regulation, expected to require 79% active average efficiency, and the Energy Star EPS 2.0, which will require 73% active average efficiency.
"The use of BJTs is prevalent in 5W and lower power supplies, where Dialog is a leader with a wide range of digital PWM controllers designed to drive BJTs," comments Ron Edgerton, Vice President and General Manager of Dialog's Power Conversion Business Group. "With the iW1679, we are applying this extensive knowledge to bring the same low cost, high efficiency and performance benefits to higher power applications."
While BJTs reduce cost compared to FETs, BJT drive requirements are more complex. The iW1679 solves this challenge by using Dialog's patented digital control technology to actively modulate the BJT base current drive.
This optimises performance and improves efficiency by keeping the BJT out of saturation. Since BJTs have softer switching compared to FETs, they generate less noise and, therefore, have inherently lower EMI. The iW1679 features Dialog's EZ-EMI, an internal EMI technique that uses valley mode switching to further reduce EMI, simplify manufacturing and minimising the need for external EMI filtering components. It also includes a proprietary switching mode that results in no audible noise from the controller.
The iW1679 lowers BOM costs up to 10% compared to FET-based designs. This BOM cost comparison is based on Dialog's analysis of published typical application circuits; and includes the cost of PWM controller IC.
Additional BOM cost savings come from Dialog's patented PrimAccurate primary-side control technology that eliminates the need for a secondary-side regulator and optical feedback isolator.
The iW1679 offers a user-configurable, four-level cable drop compensation option to eliminate the ordering and inventory challenges of stocking multiple product versions for various output voltage needs. It comes in a standard, low-cost, 8-lead SOIC package and offers full protection from fault conditions, including output short-circuit, output over-voltage, output over-current, and over-temperature protection.
iW1679 Key Features
- Output power: 5W to 10W·
- Drives low-cost, 10W BJT power switches to lower BOM cost
- Patented PrimAccurate primary-side control increases reliability, reduces solution size, lowers BOM cost
- Proprietary, adaptive multi-mode PWM/PFM optimises light-load efficiency, EMI and power consumption
- Patent-pending quasi-resonant control optimises efficiency at all loads
- High 83% active average efficiency
- Ultra-low < 30mW standby power consumption
- Meets stringent global energy efficiency standards, including: U.S. DoE, European CoC version 5, Energy Star EPS 2.0
Packaging, Pricing, Availability
The iW1679 is available now in production quantities and is priced at US $0.29 each in 1000-piece quantities.
