MAX1614 Datasheet, PDF (7/8 Pages) Maxim Integrated Products – High-Side, N-Channel MOSFET Switch Driver

High-Side, N-Channel MOSFET
Switch Driver
SHUTDOWN
OFF
(CMOS OR TTL LOGIC)
MAX1614
GND
ON
Figure 2. Single-Line Shutdown Control
N
N
LOAD
GATE SRC
ON
BATT ^MAX1614 _OFF
R1
LBI
LBO
R2
GND
TO µC
Figure 3. Single-Pushbutton On/Off Control
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,
(V_{LOW BATT}). V_{LOW BATT} = (R1 + R2) / R2 x V_TH where
V_TH is the LBI input threshold (1.20V typ). When fresh
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
degrade (Figure 4). V_{LOW BATT} = (R1 + R2) / R2 x V_TH,
where V_TH is the LBI input threshold (1.20V typ). Once
housekeeping is complete, the µP can turn off the load
by pulling OFF low.
N
N
LOAD
GATE SRC
ON
BATT ^MAX1614 _OFF
TO µC
PORT PINS
R1
LBI
TO µC
LBO
NONMASKABLE
INTERRUPT
R2
GND
Figure 4. Using LBO to Generate Early Power-Fail Interrupt
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