_______________General Description
The MAX1614 drives high-side, N-channel power MOSFETs
to provide battery power-switching functions in portable
equipment. N-channel power MOSFETs typically have
one-third the on-resistance of P-channel MOSFETs of simi-
lar size and cost. An internal micropower regulator and
charge pump generate the high-side drive output voltage,
while requiring no external components.
The MAX1614 also features a 1.5%-accurate low-battery
comparator that can be used to indicate a low-battery
condition, provide an early power-fail warning to the sys-
tem microprocessor, or disconnect the battery from the
load, preventing deep discharge and battery damage. An
internal latch allows for pushbutton on/off control with very
low current consumption. Off-mode current consumption
is only 6µA while normal operation requires less than
25µA. The MAX1614 is available in the space-saving
µMAX package that occupies about 60% less space than
a standard 8-pin SO.
________________________Applications
Notebook Computers
Portable Equipment
Hand-Held Instruments
Battery Packs
____________________________Features
o
Internal On/Off Latch
o
High-Side, N-Channel Power MOSFET Drive
o
25µA (max) Quiescent Current
o
6µA (max) Off Current
o
Requires No External Components
o
1.5%-Accurate Low-Battery Detector
o
Space-Saving µMAX Package
o
5V to 26V Input Voltage Range
o
Drives Single or Back-to-Back MOSFETs
o
Controlled Turn-On for Low Inrush Current
MAX1614
High-Side, N-Channel MOSFET
Switch Driver
________________________________________________________________
Maxim Integrated Products
1
1
2
3
4
8
7
6
5
BATT
SRC
GATE
GND
LBI
LBO
OFF
ON
MAX1614
µ
MAX
TOP VIEW
__________________Pin Configuration
MAX1614
OFF
LBO
GND
LBI
BATT
SRC
GATE
ON
N
N
LOAD
OPTIONAL FOR
REVERSE CURRENT
PROTECTION
R1
R2
__________Typical Operating Circuit
19-1176; Rev 0; 12/96
PART
MAX1614C/D
MAX1614EUA
-40°C to +85°C
0°C to +70°C
TEMP. RANGE
PIN-PACKAGE
Dice*
8 µMAX
______________Ordering Information
*
Contact factory for dice specifications.
For free samples & the latest literature: http://www.maxim-ic.com, or phone 1-800-998-8800
µA
MAX1614
High-Side, N-Channel MOSFET
Switch Driver
2
_______________________________________________________________________________________
ABSOLUTE MAXIMUM RATINGS
ELECTRICAL CHARACTERISTICS
(V
BATT
= 15V,
T
A
= 0°C to +85°C,
unless otherwise noted. Typical values are at T
A
= +25°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.
BATT, SRC to GND.................................................-0.3V to +30V
GATE to SRC ..........................................................-0.3V to +12V
GATE to GND .........................................................-0.3V to +36V
GATE + SRC Sink Current, Continuous .............................2.7mA
LBI,
LBO, ON, OFF to GND....................................-0.3V to +12V
LBO Current ..........................................................................5mA
Continuous Power Dissipation (T
A
= +70°C)
µMAX (derate 4.10mV/°C above +70°C) .....................330mW
Operating Temperature Range ...........................-40°C to +85°C
Junction Temperature ......................................................+150°C
Storage Temperature Range .............................-65°C to +160°C
Lead Temperature (soldering, 10sec) .............................+300°C
V
BATT
= 15V,
ON = OFF = unconnected,
I
GATE
= 0A, device latched on, V
LBI
= 1.5V,
SRC = BATT
V
BATT
= 5V
V
BATT
= 26V,
ON = OFF = unconnected,
I
GATE
= 0A, device latched off, V
LBI
= 1.5V
V
BATT
= 26V
V
GATE
- V
SRC
> 3V, SRC = BATT
V
BATT
= 5V
Tested at 0.6V
Tested at 2V
Tested at V
LBI
= V
BATT
/ 4
V
LBO
= 11.5V
LBI input falling
Measured from GATE to SRC, V
BATT
= 15V,
I
GATE
= 0A
V
GATE
= V
SRC
= 15V
I
SINK
= 1mA
V
GATE
= 4V, device latched off
V
LBI
= 1.3V
CONDITIONS
µs
0.5
1.0
t
PW
Minimum Input Pulse Width
V
2.0
V
IH
Input High Voltage
V
0.6
V
IL
Input Low Voltage
µA
1.5
2
Maximum Input Pull-Up Current
µA
0.5
Minimum Input Pull-Up Current
µA
0.5
V
OH
LBO High Leakage
V
0.4
V
OL
LBO Low Voltage
nA
10
I
LBI
LBI Input Current
17
30
µA
4
7
I
SHDN
V
5
26
BATT Operating Range
BATT Shutdown Current
V
0.9
4
Minimum V
BATT
for Valid
LBO
V
0.02V
TH
LBI Trip Hysteresis
V
1.182
1.20
1.218
V
TH
LBI Trip Level
V
6.5
8
9.0
V
GS
GATE Drive Voltage
µA
15
60
GATE Drive Output Current
mA
0.5
2
GATE Discharge Current
UNITS
MIN
TYP
MAX
SYMBOL
PARAMETER
V
BATT
= 26V,
ON = OFF = unconnected,
I
GATE
= 0A, device latched on, V
LBI
= 1.5V,
SRC = BATT
21
40
Measured from GATE to SRC, V
BATT
= V
SRC
= 5V,
I
GATE
= 1.5µA
3
µA
I
BATT
+
I
SRC
Quiescent Current
INTERNAL CHARGE PUMP
LOW-BATTERY COMPARATOR
CONTROL INPUTS (
ON
,
OFF
)
MAX1614
High-Side, N-Channel MOSFET
Switch Driver
_______________________________________________________________________________________
3
ELECTRICAL CHARACTERISTICS
(V
BATT
= 15V,
T
A
= -40°C to +85°C,
unless otherwise noted.) (Note 1)
__________________________________________Typical Operating Characteristics
(T
A
= +25°C, unless otherwise noted.)
22
6
5
30
ON SUPPLY CURRENT
vs. V
BATT
MAX1614-01
VBATT (V)
SUPPLY CURRENT (
µ
A)
20
14
10
10
15
18
20
12
8
16
25
T
A
= +85°C
T
A
= +25°C
T
A
= -40°C
4.0
1.0
5
30
OFF SUPPLY CURRENT
vs. V
BATT
MAX1614-02
VBATT (V)
SHUTDOWN CURRENT (
µ
A)
20
3.0
2.0
10
15
2.5
1.5
3.5
25
T
A
= +25°C
T
A
= -40°C
T
A
= +85°C
Note 1:
Specifications to -40°C are guaranteed by design and not production tested.
LOW BATTERY COMPARATOR
INTERNAL CHARGE PUMP
3
Measured from GATE to SRC, V
BATT
= 5.25V,
I
GATE
= 1.5µA, V
SRC
= 5.25V
40
PARAMETER
SYMBOL
MIN
TYP
MAX
UNITS
GATE Drive Output Current
15
60
µA
GATE Drive Voltage
V
GS
6.5
9.0
V
LBI Trip Level
V
TH
1.176
1.20
1.224
V
BATT Shutdown Current
BATT Operating Range
5.0
26
V
I
SHDN
8
µA
Quiescent Current
I
BATT
+
I
SAC
µA
CONDITIONS
V
GATE
= V
SRC
= 15V
Measured from GATE to SRC, V
BATT
= 15V,
I
GATE
= 0A
LBI input falling
V
GATE
- V
SRC
> 3V, SRC = BATT
V
BATT
= 26V,
ON = OFF = unconnected,
I
GATE
= 0A, device latched off, V
LBI
= 1.5V
V
BATT
= 26V,
ON = OFF = unconnected,
I
GATE
= 0A, device latched on, V
LBI
= 1.5V
INTERNAL CHARGE PUMP
LOW-BATTERY COMPARATOR
1.30
1.16
-40
100
LOW-BATTERY THRESHOLD
vs. TEMPERATURE
MAX1614-05
TEMPERATURE (°C)
LBI THRESHOLD (V)
40
1.24
1.20
-20
0
1.22
1.18
1.26
1.28
80
20
60
V
BATT
= 15V
V
LBI
RISING
V
LBI
FALLING
MAX1614
High-Side, N-Channel MOSFET
Switch Driver
4
_______________________________________________________________________________________
____________________________Typical Operating Characteristics (continued)
(T
A
= +25°C, unless otherwise noted.)
2.5
-0.5
0
20
GATE-DISCHARGE CURRENT
vs. GATE VOLTAGE
MAX1614-04
V
GATE
(V)
GATE-DISCHARGE CURRENT (mA)
12
1.5
0.5
4
8
1.0
0
2.0
16
2
14
6
10
18
T
A
= +85°C
T
A
= +25°C
T
A
= -40°C
30
22
5
30
GATE-CHARGING CURRENT
vs. BATT VOLTAGE
MAX1614-06
V
BATT
(V)
GATE-CHARGING CURRENT (
µ
A)
25
27
25
10
15
26
24
28
29
23
20
T
A
=
+85°C
T
A
=
-40°C
5V/div
GATE AND SOURCE TRANSITIONS
FOR TYPICAL MOSFET LOAD
1ms/div
Si9936 MOSFETS
I
LOAD
= 1A
ON = GND
V
GATE
V
SRC
V
OFF
MAX1614-07
5V/div
GATE TURN-ON TRANSITION
FOR TYPICAL MOSFET LOAD
100
µ
s/div
Si9936 MOSFETS
I
LOAD
= 1A
C
iss
= 400pF
ON = GND
V
GATE
V
SRC
V
OFF
MAX1614-08
0V
0V
5V/div
GATE TURN-OFF TRANSITION
FOR TYPICAL MOSFET LOAD
20
µ
s/div
Si9936 MOSFETS
I
LOAD
= 1A
C
iss
= 400pF
ON = GND
V
OFF
MAX1614-09
V
GATE
V
SRC
34
26
-40
0
80
100
GATE-CHARGING CURRENT
vs. TEMPERATURE
28
27
MAX1614--03
TEMPERATURE (°C)
GATE-CHARGING CURRENT (
µ
A)
40
-20
60
20
32
30
33
31
29
V
BATT
= 15V
MAX1614
High-Side, N-Channel MOSFET
Switch Driver
_______________________________________________________________________________________
5
_______________Detailed Description
The MAX1614 uses an internal, monolithic charge pump
and low-dropout linear regulator to supply the required
8V V
GS
voltage to fully enhance an N-channel MOSFET
high-side switch (Figure 1). The charge pump typically
supplies 30µA, charging 800pF of gate capacitance in
400µs (V
BATT
= 15V). For slower turn-on times, simply
add a small capacitor between the GATE and SRC
pins. When turned off, GATE and SRC pull low and typi-
cally discharge an 800pF gate capacitance in 80µs.
The MAX1614 provides separate on/off control inputs
(
ON and OFF). ON and OFF connect, respectively, to
the
SET and RESET inputs of an internal flip-flop. When
ON is pulsed low (with OFF = high), the internal charge
pump turns on, and GATE is pumped to 8V above SRC,
turning on the external MOSFETs. The charge pump
maintains gate drive to the external MOSFETs until
OFF
is pulsed low. When this happens, the internal charge
pump turns off, and GATE discharges to ground
through an internal switch. For slower turn-on times,
simply add a small capacitor.
__________ Applications Information
Connecting
ON/OFF to 3V or 5V Logic
ON and OFF internally connect to 2µA max pull-up
current sources (Figure 1). The open-circuit voltage
for
ON and OFF ranges from 7V to 10.5V (nominally
8.5V). Since the current sources are relatively weak,
connecting
ON and OFF directly to logic powered from
lower voltages (e.g., 3V or 5V) poses no problem if the
gate outputs driving these pins can sink at least 2µA
while high.
Although the MAX1614 shutdown function was designed
to operate with a single pushbutton on/off switch, it can
also be driven by a single gate. Connect
ON to GND
and drive
OFF directly (Figure 2).
Maximum Switching Rate
The MAX1614 is not intended for fast switching appli-
cations. In fact, it is specifically designed to limit the
rate of change of the load current,
I/
t. The maximum
switching rate is limited by the turn-on time, which is a
function of the charge-pump output current and the
total capacitance on GATE (C
GATE
). Calculate the turn-
on time as a function of external MOSFET gate capaci-
tance using the Gate Charging Current vs. V
BATT
graph
in the
Typical Operating Characteristics. Since turn-off
time is small compared to turn-on time, the maximum
switching rate is approximately 1/t
ON
.
Adding Gate Capacitance
The charge pump uses an internal monolithic transfer
capacitor to charge the external MOSFET gates.
Normally, the external MOSFET's gate capacitance is
sufficient to serve as a reservoir capacitor. If the
MOSFETs are located at a significant distance from the
MAX1614, place a local bypass capacitor (100pF typ)
across the GATE and SRC pins. For slower turn-on
times, simply add a small capacitor between GATE and
SRC.
______________________________________________________________Pin Description
System Ground
GND
5
Gate-Drive Output. Connect to the gates of external, N-channel MOSFETs. When the MAX1614 is off, GATE
actively pulls to GND.
GATE
6
Source Input. Connect to the sources of external, N-channel MOSFETs. When the MAX1614 is off, SRC
actively pulls to GND.
SRC
7
Battery Input. Connect to a battery voltage between 5V and 26V.
BATT
8
Low-Battery Comparator Input.
LBO goes low when V
LBI
falls below 1.20V (typ). Connect a voltage divider
between BATT, LBI, and GND to set the battery undervoltage trip threshold (see
Typical Operating Circuit).
LBI
4
Open-Drain, Low-Battery Comparator Output.
LBO is low when V
LBI
is below the trip point.
LBO
3
PIN
RESET Input to the On/Off Latch. Pulse OFF low with ON high to turn off the external MOSFET switch. When
both
ON and OFF are low, the part is off.
OFF
2
SET Input to the On/Off Latch. Pulse ON low with OFF high to turn on the external MOSFET switch. When
both
ON and OFF are low, the part is off.
ON
1
FUNCTION
NAME
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