Step-down dc/dc converters deliver 500mA with over 90% efficiency
( 01 Dec 2003 )
Maxim Integrated Products has introduced the MAX8560/MAX8561/MAX8562, said to be the first 4MHz, high-efficiency, step-down dc/dc converters that provide up to 500mA of continuous current at output voltages as low as 0.6V in tiny SOT23 and thin DFN packages.
These devices are optimized for applications where small size and efficiency are critical. Applications include cell phones, PDAs, digital still cameras (DSC), and wireless LAN.
The MAX8560/MAX8561/MAX8562 utilize a proprietary, hysteric PWM scheme that switches at up to 4MHz. This user-adjustable switching frequency scheme allows the use of a 1mm high, 1 microhenrie inductor and tiny low-cost ceramic capacitors, providing a complete solution of less than 19.5mm squared. No-load quiescent current is 40mA.
Low-output ripple minimizes the impact on the RF operation of portable communicators, including cell phones, smartphones, and PDA phones. These devices also include internal soft-start with zero inrush current.
The MAX8560/MAX8561/MAX8562 have an input range of 2.7 to 5.5V for single-cell lithium-ion (Li+), multicell alkaline, or NiMH battery power applications.
The MAX8561 features logic-controlled output-voltage selection, providing two output voltages for dynamic-voltage management (DVM) for the CPU core supply. To minimize power loss through the inductor in the power-amplifier (PA) applications, the MAX8562 drives an external bypass P-channel FET when in high-power mode.
The MAX8560 is packaged in a 6-pin SOT23, and the MAX8561/MAX8562 are packaged in 3x3mm, 8-pin, thin DFN. $1.85 (1000).
