MAX624

` 1MHz Switching Frequency for Small Components
` 5V ±4% Boost Converter with Internal Power Switch
` Adjustable ±2% Output Boost Converter with External Power Switch
` Optional Inrush Surge-Current Limiting
` 40A Shutdown Current
` 0.5mA Quiescent Current
` 3.0V to 5.5V Input Range
` 85% Main 5V SMPS Efficiency
` Independent Soft-Start for Each Supply
` Reset Output with 2.8V ±3% Threshold and 4ms Timeout

VIN, FB5, LX5, SHDN, ONA to GND...........................-0.3V to 7V
EXT to GND............................................................-0.3V to 12V
RESET, REF to GND...................................-0.3V to (VIN + 0.3V)
PGND to GND..................................................................±0.3V
SS5, SSA, DA, CSA, FBA to GND................-0.3V to (FB5 + 0.3V)
VA to GND ............................................................-0.3V to 17V
Continuous Power Dissipation (T_A = +70°C)
   SO (derate 8.70mW/°C above +70°C)...................696mW
Operating Temperature Range
   MAX624ISE................................................-25°C to +85°C
Lead Temperature (soldering, 10sec) .......................+300°C

Stresses beyond those listed under "Absolute Maximum Ratings" may cause permanent damage to the device. These are stress ratings only, and functional operation of the device at these or any other conditions beyond those indicated in the operational sections of the specifications is not implied. Exposure to absolute maximum rating conditions for extended periods may affect device reliability.

The MAX624 is a dual DC-DC converter intended for size-constrained applications, such as power supplies that must fit inside PCMCIA memory cards. At the heart of the MAX624 are two boost-topology converters, plus auxiliary functions including a start-up inrush surge-current limiter and a power-on reset output with timer (power-good signal). The MAX624 accepts input voltages from 3V to 5.5V and generates two outputs: a fixed 5V ±4% output at 200mA (guaranteed), and an adjustable auxiliary output that is configurable for various loads with an external power transistor. The auxiliary output is typically set to 12V ±2% for flash memory applications, but can be adjusted via a resistor divider from V_IN to 30V or more.

The MAX624's high switching frequency (1MHz) reduces external component sizes. High-frequency switching losses have minimal impact on efficiency,which is 85% for the main 5V supply. Small ceramic filter capacitors, together with the soft-start function,reduce start-up inrush current surges.