500mV to 5.5V Input nanoPower

Boost Converter with Short-Circuit

Protection

and True Shutdown

MAX18000

www.analog.com

Analog Devices | 11

Detailed Description

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 as shown in Table 1. 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.

Table 1. RSEL Selection Table

OUTPUT VOLTAGE (V)

RSEL (kΩ)**

2.5

768

2.6

634

2.7

536

2.8

452

2.9

383

3.0

324

3.1

267

3.2

226

3.3

191

3.4

162

3.5

133

3.6

113

3.7

95.3

3.8

80.6

3.9

66.5

4.0

56.2

4.1

47.5

4.2

40.2

4.3

34

4.4

28

4.5

23.7