High-Side, n-Channel MOSFET

Switch Driver

_______________________________________________________________________________________

7

On/Off Control with a

Single Pushbutton Switch

The MAX1614’s separate on and off inputs allow maxi-

mum flexibility in controlling the external MOSFETs.

Connect a pushbutton switch to the ON pin and micro-

controller (µC) I/O for single-button control. Connect the

OFF pin to another µC I/O pin. On the first button

depression, the MAX1614 turns on automatically; the

signal is also detected by the µC. When the button is

depressed a second time, the µC wraps around and

turns off the MAX1614 by pulling low on the OFF pin

(Figure 3).

Simple Low-Battery Disconnect/Fresh

Battery Reconnect Circuit

A simple undervoltage disconnect circuit is often desir-

able to prevent damage to secondary batteries due to

repeated deep discharge or cell reversal. The

Typical

Operating Circuit turns off the MAX1614, disconnecting

the battery from the load when the battery voltage

falls below the minimum battery voltage required,

cells are installed or the batteries are recharged, a µC

or pushbutton reconnects the load.

Using

LBO to Generate Early

Power-Fail Interrupt

Many applications require an early warning indicating

that power is failing so that the microprocessor (µP)

can take care of any “housekeeping” functions (storing

current settings in memory, etc.) before the power fails.

Connect LBI through a resistor divider across the bat-

tery, and connect LBO to the µP nonmaskable interrupt

(NMI). Set the threshold so that LBO goes low when the

battery decays to a point where regulation begins to

housekeeping is complete, the µP can turn off the load

by pulling OFF low.

MAX1614

SHUTDOWN

(CMOS OR TTL LOGIC)

GND

ON

OFF

Figure 2. Single-Line Shutdown Control

MAX1614

OFF

LBO

GND

LBI

BATT

SRC

GATE

ON

NN

LOAD

TO µC

R1

R2

Figure 3. Single-Pushbutton On/Off Control

MAX1614

OFF

LBO

GND

LBI

BATT

SRC

GATE

ON

NN

LOAD

TO µC

PORT PINS

TO µC

NONMASKABLE

INTERRUPT

R1

R2

Figure 4. Using LBO to Generate Early Power-Fail Interrupt