Descripción general

The MAX18000 is a nanoPower boost converter with an input voltage range of 0.5V to 5.5V (VOUT > VIN + 0.2V) and a switching current limit of 3.6A. It features an ultra low quiescent current of 512nA which makes it ideal for battery-powered applications requiring a long standby time. The IC operates in nanoPower mode at low loads and transitions into skip and CCM modes of operation at higher load currents to ensure high efficiency over a wide current range.

The output voltage can be varied between 2.5V and 5.5V using a single RSEL resistor.

The IC features a True Shutdown™ mode, which disconnects VIN and VOUT when the EN pin is pulled low. It also features short-circuit protection circuitry that limits the current to 700mA when VOUT < 0.5V and automatically restarts the part when the fault is removed. The thermal-shutdown protection disables the part when the junction temperature crosses +165°C (typ). The IC is available in 1.07mm x 1.57mm, 6-bump waferlevel package (WLP).

 

Ventajas y características

0.5V to 5.5V Input Voltage (VOUT > VIN + 0.2V)

1.8V Minimum Start-Up Voltage

2.5V to 5.5V (In 100mV Steps) Output Voltage

3.6A Cycle-by-Cycle Inductor Current Limit

512nA IQ Supply Current into the Output

True-Shutdown Mode – 7nA Shutdown Current – Output Disconnects from Input with no Forward or Reverse Current

Output Short-Circuit Protection

Thermal-Shutdown Protection

95% Peak Efficiency with 90% or Higher Efficiency for Load > 20µA

1.07mm x 1.57mm, 0.5mm Pitch 6-Bump WLP

-40°C to +125°C Operating Temperature Range

 

Key Applications

Wearable Applications

IoT Applications

Battery-Powered Applications

Portable Devices

Metering Applications

 

Descripción detallada

The MAX18000 is a nanoPower boost converter with an input voltage range of 500mV to 5.5V ideal for battery power applications with long standby times. The start-up voltage required for the IC is about 1.8V (typical). The output voltage is adjustable between 2.5V and 5.5V (in steps of 100mV) using a single external resistor connected between RSEL and GND. For the part to operate in boost mode, it is essential to keep the VIN level at least 200mV below the VOUT level. The low quiescent current helps the part maintain high efficiency at low loads (about 90% at a load of 20µA). The IC operates in three modes according to the load current: nanoPower mode, skip mode, and continuous conduction mode (CCM). In nanoPower mode, the part deactivates the error amplifier and other internal blocks to lower IQ.  The part is equipped with a cycle-to-cycle switch current limit, thermal shutdown, and short-circuit protection to protect the system and the device itself.

 

Output-Voltage Selection

The MAX18000 has a unique single resistor output selection method where the resistor connected between RSEL and GND is used to select different output voltages from 2.5V to 5.5V (nanoPower mode disabled for target VOUT > 5V) in 100mV steps. The advantages of using a single RSEL for output voltage selection are as follows:

Lower cost and smaller size, since only one resistor is needed versus the two resistor strings needed in typical feedback connections.

No power loss through feedback resistors during operation, leading to higher efficiency.

Allows customers to stock just one part in their inventory system and use it in multiple projects with different output voltages just by changing a single standard 1% resistor.

 

Boost Control Scheme

The MAX18000 operates based on an adaptive on-time current-mode control. Adaptive on-time is used to get a fast transient response and better efficiency across the operating range. In both continuous conduction mode (CCM) and discontinuous conduction mode (DCM), the on-time is adjusted depending on the input voltage and target output voltage.

 

nanoPower Mode

The MAX18000 automatically enters nanoPower mode when the load current is very low to achieve high efficiency at light loads. When the load current is reduced, the switching frequency also reduces. When the switching frequency reduces below 28kHz (typical), the part enters nanoPower mode. In nanoPower mode, the part turns off the error amplifier and other internal blocks to reduce the power consumption and goes to sleep. Once the VOUT level drops below the threshold, the part wakes up and initiates switching cycles to bring the output voltage into regulation. The device regulates to 102.5% of the target voltage when operating in nanoPower mode. When the load is increased and the VOUT level drops below the threshold, the part starts switching and enters normal operation (DCM or CCM mode).