19-3495; Rev 0; 11/04
High-Voltage, Low-Power Linear Regulators for
Notebook Computers
General Description
The MAX8718/MAX8719 are micropower, 8-pin TDFN
linear regulators that supply always-on, keep-alive
power to CMOS RAM, real-time clocks (RTC), and
microcontrollers in systems with high-voltage batteries.
The circuits consist of a 100mA linear regulator and a
power-good comparator (PGOOD) with fixed-output
delay. Key features include wide input voltage range,
low-dropout voltage, and low-quiescent supply current.
Despite a miserly 25µA (max) no-load quiescent cur-
rent, the MAX8718/MAX8719 have good line- and load-
transient response and excellent AC power-supply
rejection. They provide a clean fixed 5V or 3.3V output
(MAX8718), or an adjustable 1.24V to 28V output
(MAX8719), even when subjected to fast supply-volt-
age changes that occur during the switchover from bat-
tery to AC-adapter input power. The space-saving
TDFN package has excellent thermal characteristics
and tolerates up to 1951mW of power dissipation.
Internal foldback current limiting and thermal shutdown
protect the regulator from overload and thermal faults.
In addition to the main notebook-computer application,
these devices are useful in other low-power, high-volt-
age applications (4V < V
IN
< 28V) such as smart batter-
ies, current control loops, telecom emergency power,
and housekeeping power for off-line supplies.
The MAX8718/MAX8719 are available in a thermally
enhanced 3mm x 3mm, 8-lead TDFN package.
♦
4V to 28V Input Range
♦
18µA Quiescent Supply Current
♦
<3µA Shutdown Supply Current
♦
100mA Output Current
♦
3.3V or 5V, Pin-Selectable Output (MAX8718)
♦
Adjustable 1.24V to 28V Output (MAX8719)
♦
±2% Output Accuracy
♦
Thermal-Overload Protection
♦
Delayed Power-Good Output
♦
Thermally Enhanced 8-Pin TDFN Package
Features
MAX8718/MAX8719
Ordering Information
PART
TEMP RANGE PIN-PACKAGE
8 TDFN 3mm x
3mm
8 TDFN 3mm x
3mm
OUTPUT
VOLTAGE
3.3V/5V
Adjustable
MAX8718ETA
-40°C to +85°C
MAX8719ETA
-40°C to +85°C
Applications
CMOS/RTC Backup Power
Microcontroller Power
Notebook Computers
Smart-Battery Packs
PDAs and Handy-Terminals
Battery-Powered Systems
IN 1
GND 2
5/3 (FB) 3
V
CC
4
Pin Configuration
TOP VIEW
8 OUT
MAX8718
MAX8719
7 I.C.
6 SHDN
5 PGOOD
TDFN
3mm
×
3mm
() ARE FOR THE MAX8719.
________________________________________________________________
Maxim Integrated Products
1
For pricing, delivery, and ordering information, please contact Maxim/Dallas Direct! at
1-888-629-4642, or visit Maxim’s website at www.maxim-ic.com.
High-Voltage, Low-Power Linear Regulators for
Notebook Computers
MAX8718/MAX8719
ABSOLUTE MAXIMUM RATINGS
IN to GND ...............................................................-0.3V to +30V
SHDN
to GND ..............................................-0.3V to (V
IN
+ 0.3V)
5/3 (MAX8718) to GND.............................................-0.3V to +6V
FB (MAX8719) to GND .............................................-0.3V to +6V
OUT (MAX8718) to GND ..........................................-0.3V to +6V
OUT (MAX8719) to GND ........................................-0.3V to +30V
V
CC
to GND (MAX8718) ...........................................-0.3V to +6V
V
CC
to GND (MAX8719) ........................................-0.3V to +2.7V
PGOOD to GND .....................................................-0.3V to +30V
I.C. to GND ...............................................................-0.3V to +6V
OUT Short Circuit to GND.......................................................30s
Continuous Power Dissipation (T
A
= +70°C)
8-Pin TDFN (derate 24.4mW/°C above +70°C) ..........1951mW
Operating Temperature Range ...........................-40°C to +85°C
Junction Temperature ......................................................+150°C
Storage Temperature Range .............................-65°C to +150°C
Lead Temperature (soldering, 10s) .................................+300°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.
ELECTRICAL CHARACTERISTICS
(Circuit of Figure 1. V
IN
= 15V, I
OUT
= 5µA,
T
A
= 0°C to +85°C.
Typical values are at T
A
= +25°C, unless otherwise noted.) (Note 1)
PARAMETER
Input Voltage Range
Supply Current (MAX8718)
V
CC
Input Current (MAX8719)
V
CC
Input Current (MAX8718)
OUT Minimum Load Current
Shutdown Supply Current
Dropout Supply Current
SHDN
= 0V
V
OUT
set to 5V, V
IN
= 4.7V
V
IN
= 6V to 28V, I
LOAD
= 1mA, 5/3 = GND,
T
A
= +25°C
V
IN
= 6V to 28V, I
LOAD
= 1mA, 5/3 = OUT,
T
A
= +25°C
V
IN
= 6V to 28V, I
LOAD
= 5µA to 100mA,
5/3 = GND
V
IN
= 6V to 28V, I
LOAD
= 5µA to 100mA,
5/3 = OUT
FB = OUT, V
IN
= 6V to 28V, I
LOAD
= 1mA
FB Threshold (MAX8719)
V
FB
FB = OUT, V
IN
= 6V to 28V,
I
LOAD
= 5µA to 100mA (Note 2)
V
FB
= 1.3V, T
A
= +25°C
V
FB
= 1.3V, T
A
= 0°C to +85°C
V
5/3
= 5V, T
A
= +25°C
V
5/3
= 5V, T
A
= 0°C to +85°C
-30
2
560
3.26
4.95
3.15
4.75
1.215
1.18
-30
15
+30
1.240
1.2
85
3.33
5.05
3.40
5.15
V
3.48
5.25
1.265
1.28
+30
V
SYMBOL
V
IN
I
IN
SHDN
= IN, T
A
= +25°C
SHDN
= IN, V
IN
= 6V to 28V
0V < V
CC
< 2.7V, T
A
= +25°C
0V < V
CC
< 2.7V, T
A
= 0°C to +85°C
0V < V
CC
< 5.5V, T
A
= +25°C
0V < V
CC
< 5.5V, T
A
= 0°C to +85°C
2.3
5
3
-0.1
0.04
3.4
CONDITIONS
MIN
4
12
TYP
MAX
28
18
25
+0.1
UNITS
V
µs
µA
µA
µA
µA
µA
µA
OUT Output Voltage (MAX8718)
FB Input Current (MAX8719)
5/3 Input Current (MAX8718)
Dropout Voltage
I
FB
I
5/3
nA
nA
mV
V
DROPOUT
I
LOAD
= 100mA (Note 3)
2
_______________________________________________________________________________________
High-Voltage, Low-Power Linear Regulators for
Notebook Computers
ELECTRICAL CHARACTERISTICS (continued)
(Circuit of Figure 1. V
IN
= 15V, I
OUT
= 5µA,
T
A
= 0°C to +85°C.
Typical values are at T
A
= +25°C, unless otherwise noted.) (Note 1)
PARAMETER
Output Current Limit
Output Reverse Leakage Current
Capacitive Load Requirements
SYMBOL
I
LIM
CONDITIONS
V
IN
= 6V, T
A
= +25°C
V
OUT
= 0, V
IN
= 6V
V
OUT
forced to 5.5V, IN = unconnected
MAX8718
MAX8719
Rising edge of IN or
SHDN
to OUT within
spec limits, C
OUT
= 10µF, R
LOAD
= 500Ω,
V
OUT
= 5V
C
OUT
= 10µF, R
LOAD
= 500Ω, OUT within
90% of the nominal output voltage
T
A
= +25°C, rising edge only
V
CC
Threshold (MAX8718)
0°C < T
A
< +85°C, rising edge only
T
A
= +25°C, rising edge only
V
CC
Threshold (MAX8719)
0°C < T
A
< +85°C, rising edge only
V
CC
to PGOOD Delay
PGOOD Active-Timeout Period
PGOOD Output Leakage Current
PGOOD Output Low Voltage
V
CC
Input Hysteresis
Thermal-Shutdown Threshold
SHDN
Input Low Voltage
SHDN
Input High Voltage
SHDN
Input Bias Current
V
SHDN
= 0 or 15V, T
A
= 0°C to +85°C
1.4
-1
+0.1
+1
V
SHDN
= 0 or 15V, 20°C hysteresis
PGOOD = 5.5V, V
CC
= 5.5V
I
SINK
= 1.6mA, V
CC
= GND
2
+165
0.25
V
TH
to (V
TH
- 100mV)
100
0.88
×
V
OUT
0.85
×
V
OUT
0.88
×
V
FB
0.85
×
V
FB
0.5
0.9
×
V
OUT
0.9
×
V
OUT
0.9
×
V
FB
0.9
×
V
FB
4.5
185
300
0.1
0.3
0.92
×
V
OUT
0.95
×
V
OUT
0.92
×
V
FB
0.95
×
V
FB
0.16
0.23
1
125
70
MIN
TYP
210
340
MAX
UNITS
mA
µA
µF/mA
MAX8718/MAX8719
Startup Time Response
ms
Startup Output Overshoot
%
V
V
µs
ms
µA
V
%
°C
V
V
µA
_______________________________________________________________________________________
3
High-Voltage, Low-Power Linear Regulators for
Notebook Computers
MAX8718/MAX8719
ELECTRICAL CHARACTERISTICS
(Circuit of Figure 1 V
IN
= 15V, I
OUT
= 5µA,
T
A
= -40°C to +85°C,
unless otherwise noted.) (Note 4)
PARAMETER
Input Voltage Range
Supply Current (MAX8718)
Supply Current (MAX8719)
OUT Minimum Load Current
Shutdown Supply Current
SHDN
= 0V
V
IN
= 6V to 28V, I
LOAD
= 5µA to 100mA,
5/3 = GND
OUT Output Voltage (MAX8718)
V
IN
= 6V to 28V, I
LOAD
= 5µA to 100mA,
5/3 = OUT
FB = OUT, V
IN
= 6V to 28V, I
LOAD
= 1mA
FB Threshold (MAX8719)
FB Input Current (MAX8719)
5/3 Input Current (MAX8718)
Dropout Voltage
Output Current Limit
Capacitive Load Requirements
V
FB
I
FB
I
5/3
I
LIM
FB = OUT, V
IN
= 6V to 28V,
I
LOAD
= 5µA to 100mA (Note 2)
V
FB
= 1.3V
V
5/3
= 5V
V
OUT
= 0, V
IN
= 6V
MAX8718
MAX8719
Rising edge of IN or
SHDN
to OUT within
spec limits, C
OUT
= 10µF, R
LOAD
= 500Ω,
V
OUT
= 5V
-40°C < T
A
< +85°C, rising edge only
-40°C < T
A
< +85°C, rising edge only
0.85
×
V
OUT
0.85
×
V
FB
100
I
SINK
= 1.6mA, V
CC
= GND
1.4
V
SHDN
= 0 or 15V, T
A
= -40°C to +85°C
-1
+1
4.72
1.215
1.18
-40
-30
125
0.16
0.23
1
0.95
×
V
OUT
0.95
×
V
FB
300
0.3
0.25
5.25
1.265
1.28
+40
+30
560
375
V
nA
nA
mV
mA
µF/mA
3.10
SYMBOL
V
IN
I
IN
I
IN
SHDN
= IN, V
IN
= 6V to 28V
SHDN
= IN, V
IN
= 6V to 28V
CONDITIONS
MIN
4
TYP
MAX
28
25
25
5
3
3.48
V
UNITS
V
µA
µA
µA
µA
V
DROPOUT
I
LOAD
= 100mA (Note 3)
Startup Time Response
ms
V
CC
Threshold (MAX8718)
V
CC
Threshold (MAX8719)
PGOOD Active-Timeout Period
PGOOD Output Low Voltage
SHDN
Input Low Voltage
SHDN
Input High Voltage
SHDN
Input Bias Current
V
V
ms
V
V
V
µA
Note 1:
Limits are 100% production tested at T
A
= +25°C. Limits over the operating temperature range are guaranteed through cor-
relation using standard quality control (SQC) methods.
Note 2:
Pulse test at V
IN
= 28V, I
OUT
= 100mA to avoid exceeding package power-dissipation limits.
Note 3:
Dropout voltage is tested by reducing the input voltage until V
OUT
drops to 100mV below its nominal value as measured
with V
IN
starting 2V above V
OUT
.
Note 4:
Specifications to -40°C are guaranteed by design, not production tested.
4
_______________________________________________________________________________________
High-Voltage, Low-Power Linear Regulators for
Notebook Computers
MAX8718/MAX8719
Typical Operating Characteristics
(Circuit of Figure 1. V
IN
= 15V, V
OUT
= 3.3V, T
A
= +25°C, unless otherwise noted.)
SAFE LOAD-CURRENT OPERATING AREA
vs. SUPPLY VOLTAGE
MAX8718/19 toc01
GROUND CURRENT vs. SUPPLY VOLTAGE
AT VARIOUS LOADS
MAX8718/19 toc02
SUPPLY CURRENT vs. SUPPLY VOLTAGE
18.5
SUPPLY CURRENT (µA)
18.0
17.5
17.0
16.5
16.0
15.5
T
A
= -40
°
C
T
A
= +25
°
C
T
A
= +85
°
C
MAX8718/9 toc03
120.0
100.0
LOAD CURRENT (mA)
80.0
60.0
40.0
20.0
0
0
5
10
15
20
25
POWER-DISSIPATION
LIMIT REGION
15.0
150mA
GROUND CURRENT (mA)
12.0
110mA
9.0
70mA
6.0
30mA
3.0
10mA
19.0
0
30
5
10
15
20
25
30
SUPPLY VOLTAGE (V)
SUPPLY VOLTAGE (V)
15.0
5
10
15
20
25
30
SUPPLY VOLTAGE (V)
SHUTDOWN SUPPLY CURRENT
vs. SUPPLY VOLTAGE
MAX8718/19 toc04
SUPPLY CURRENT vs. TEMPERATURE
MAX8718/9 toc05
RIPPLE REJECTION vs. FREQUENCY
-70
RIPPLE REJECTION (dB)
-60
-50
-40
-30
-20
-10
10mA LOAD CURRENT
0
MAX8718/19 toc06
1.6
SHUTDOWN SUPPLY CURRENT (µA)
1.4
1.2
1.0
0.8
0.6
0.4
0.2
T
A
= +25°C
0
2
6
10
14
18
22
26
19.0
18.5
SUPPLY CURRENT (µA)
18.0
17.5
17.0
16.5
16.0
15.5
15.0
V
IN
= 15V
-80
30
-40
-20
0
20
40
60
80
100
0.01
0.1
1
FREQUENCY (kHz)
10
100
SUPPLY VOLTAGE (V)
TEMPERATURE (
°
C)
LOAD-TRANSIENT RESPONSE
MAX8718/9 toc07
LINE-TRANSIENT RESPONSE
MAX8718/9 toc08
V
OUT
100mV/div
V
OUT
200mV/div
AC-COUPLED
+20V
V
IN
I
OUT
100mA/div
C
IN
= 10µF, C
OUT
= 10µF
200µs/div
100µs/div
+10V
_______________________________________________________________________________________
5
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