19-1225; Rev 3; 9/04
High-Voltage, Low-Power Linear Regulators
for Notebook Computers
________________General Description
The MAX1615/MAX1616 are micropower, SOT23-5 lin-
ear regulators that supply always-on, keep-alive power
to CMOS RAM and microcontrollers (µCs) in systems
with high-voltage batteries. Key features include wide
input voltage range, low dropout voltage, and low qui-
escent supply current.
Despite a miserly 8µA (max) no-load supply current, the
MAX1615/MAX1616 have excellent line-transient
response and AC power-supply rejection ratio. They
provide a clean, fixed 5V or 3.3V output (MAX1615) or
an adjustable 1.24V to 28V output (MAX1616), even
when subjected to fast supply-voltage changes that
occur during the switchover from battery to AC adapter
input power. The space-saving SOT23-5 package has
excellent thermal characteristics and tolerates up to
571mW of power dissipation. Fault protection is provid-
ed by internal foldback current limiting and thermal-
shutdown circuitry. The MAX1615/MAX1616 are now
available in lead-free packages.
____________________________Features
♦
4V to 28V Input Range
♦
8µA (max) Quiescent Supply Current
♦
<1µA Shutdown Supply Current
♦
3.3V or 5V, Pin-Selectable Output (MAX1615)
Adjustable 1.24V to 28V Output (MAX1616)
♦
30mA Output Current
♦
±2% Initial Output Accuracy
♦
Thermal-Overload Protection
♦
5-Pin SOT23 Package
♦
Low Cost
MAX1615/MAX1616
________________________Applications
CMOS/RTC Backup Power
Microcontroller Power
Notebook Computers
Smart-Battery Packs
PDAs and Handy-Terminals
Battery-Powered Systems
_______________Ordering Information
PART
MAX1615EUK-T
MAX1615EUK+T
MAX1616EUK-T
MAX1616EUK+T
TEMP RANGE
-40°C to +85°C
-40°C to +85°C
-40°C to +85°C
-40°C to +85°C
PIN-
SOT
PACKAGE TOP MARK
5 SOT23-5
5 SOT23-5
5 SOT23-5
5 SOT23-5
ABZD
ABZD
ABZE
ABZE
+Denotes
lead-free package.
____________Typical Operating Circuit
___________________Pin Configuration
TOP VIEW
IN
OUT
OUTPUT
VOLTAGE
IN
1
5
SHDN
MAX1615
BATTERY
C
IN
0.1µF
SHDN
GND
5/3
C
OUT
4.7µF
GND
2
MAX1615
MAX1616
4
5/3 (FB)
OUT
3
SOT23-5
( ) ARE FOR MAX1616.
________________________________________________________________
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
MAX1615/MAX1616
ABSOLUTE MAXIMUM RATINGS
IN to GND .................................................................-0.3V to 30V
Terminal Voltages to GND
SHDN
to GND ...........................................-0.3V to (V
IN
+ 0.3V)
5/3 to GND ............................................-0.3V to (V
OUT
+ 0.3V)
FB (MAX1616) to GND .........................-0.3V to (V
OUT
+ 0.3V)
OUT to GND...........................................................-0.3V to 30V
OUT Short-Circuit to GND ...............................................30sec
Note 1:
See
Operating Region and Power Dissipation
section.
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.
Continuous OUT Current.....................................................40mA
Continuous Power Dissipation (T
A
= +70°C) (Note 1)
SOT23-5 (derate 7.1mW/°C above +70°C)...................571mW
Operating Temperature Range
MAX161_EUK-T ...............................................-40°C to +85°C
Storage Temperature Range .............................-65°C to +160°C
Lead Temperature (soldering, 10s) .................................+300°C
ELECTRICAL CHARACTERISTICS
(V
IN
= 15V,
SHDN
= V
IN
, I
LOAD
= 5µA, T
A
= T
MIN
to T
MAX
, unless otherwise noted. Typical values are at T
A
= +25°C.) (Note 2)
PARAMETER
Input Voltage Range
Supply Current
Minimum Load Current
Shutdown Supply Current
Dropout Supply Current
I
IN
SHDN
= GND
(shutdown mode)
Output set to 5V,
V
IN
= 4V
I
LOAD
= 1mA,
T
A
= +25°C,
V
IN
= 6V to 28V
I
LOAD
= 5µA to 30mA,
T
A
= T
MIN
to T
MAX
,
V
IN
= 6V to 28V
FB = OUT,
V
IN
= 6V to 28V
V
FB
= 1.3V
I
LOAD
= 30mA (Note 4)
V
IN
= 6V
IN = unconnected, V
OUT
forced to 5V
MAX1615
MAX1616
Rising edge of IN or
SHDN
to OUT within specifi-
cation limits, R
L
= 500Ω, C
OUT
= 6.8µF,
V
OUT
set to 5V
V
OSH
R
L
= 500Ω, C
OUT
= 10µF within 90% of nominal
output voltage
0.5
0.16
0.23
1
100
70
T
A
= +25°C
T
MIN
= T
MIN
to T
MAX
T
A
= +25°C
5/3 = GND
5/3 = OUT
5/3 = GND
5/3 = OUT
T
A
= +25°C,
I
LOAD
= 1mA
T
A
= T
MIN
to T
MAX
,
I
LOAD
= 5µA to 30mA
3.26
4.95
3.15
4.75
1.215
1.18
-10
12
1.240
70
3.33
5.05
3.40
5.15
V
3.48
5.25
1.265
1.28
30
350
V
V
nA
mV
mA
µA
µF/mA
SYMBOL
V
IN
I
IN
SHDN
= IN, T
A
= +25°C
SHDN
= IN, V
IN
= 6V to 28V, T
A
= T
MIN
to T
MAX
CONDITIONS
MIN
4
6.2
TYP
MAX
28
8
15
5
1.5
3
UNITS
V
µA
µA
µA
µA
Output Voltage (MAX1615)
(Note 3)
FB Threshold (MAX1616)
(Note 3)
FB Input Current (MAX1616)
Dropout Voltage
Output Current Limit
OUT Reverse Leakage
Current
Capacitive Load
Requirements (Note 5)
Start-Up Time Response
V
FBT
I
FB
∆V
DO
ms
Start-Up Overshoot
%V
OUT
2
_______________________________________________________________________________________
High-Voltage, Low-Power Linear Regulators
for Notebook Computers
MAX1615/MAX1616
ELECTRICAL CHARACTERISTICS (continued)
(V
IN
= 15V,
SHDN
= V
IN
, I
LOAD
= 5µA, T
A
= T
MIN
to T
MAX
, unless otherwise noted. Typical values are at T
A
= +25°C.) (Note 2)
PARAMETER
SHDN
Input Threshold
Voltage
SHDN
Input Current
Thermal-Shutdown
Temperature
T
SHDN
SYMBOL
V
IL
V
IH
V
SHDN
= 0V or 15V
V
SHDN
= 0V or 15V, hysteresis = +20°C
1.4
-1
150
1
CONDITIONS
MIN
TYP
MAX
0.25
UNITS
V
µA
°C
Note 2:
Limits are 100% production tested at T
A
= +25°C. Limits over the operating temperature range are guaranteed through
correlation using standard quality-control (SQC) methods.
Note 3:
Pulse tested at V
IN
= 28V, I
LOAD
= 30mA to avoid exceeding package power-dissipation limits.
Note 4:
Guaranteed by design. Tested with V
OUT
set to 5V. Dropout voltage is tested by reducing the input voltage until V
OUT
drops
to 100mV below its nominal value, measured with V
IN
starting 2V above V
OUT
.
Note 5:
Use at least 1µF minimum for light loads. Add 0.125µF/mA (0.2µF/mA for the MAX1616) for loads greater than 100µA,
not production tested. See
Capacitor Selection
in the
Applications Information
section.
__________________________________________Typical Operating Characteristics
(V
OUT
set to 5V, T
A
= +25°C, unless otherwise noted.)
SAFE LOAD-CURRENT
OPERATING AREA
vs. SUPPLY VOLTAGE
MAX1615-01
GROUND CURRENT
vs. SUPPLY VOLTAGE
AT VARIOUS LOADS
MAX1615-02
SUPPLY CURRENT
vs. SUPPLY VOLTAGE
8.5
SUPPLY CURRENT (µA)
8.0
7.5
7.0
6.5
6.0
5.5
5.0
5
10
T
A
= +85°C
T
A
= +25°C
T
A
= -40°C
15
20
25
30
MAX1615-03
60
V
OUT
= 5V
50
OUTPUT CURRENT (mA)
40
30
20
10
0
0
5
10
15
20
25
POWER-
DISSIPATION
LIMIT REGION
8
7
GROUND CURRENT (mA)
6
5
4
3
2
1
0
15mA
5
10
15
20
25
45mA
35mA
25mA
5mA
65mA
55mA
9.0
30
30
SUPPLY VOLTAGE (V)
SUPPLY VOLTAGE (V)
SUPPLY VOLTAGE (V)
_______________________________________________________________________________________
3
High-Voltage, Low-Power Linear Regulators
for Notebook Computers
MAX1615/MAX1616
____________________________Typical Operating Characteristics (continued)
(V
OUT
set to 5V, T
A
= +25°C, unless otherwise noted.)
SHUTDOWN SUPPLY CURRENT
vs. SUPPLY VOLTAGE
MAX1615-04
RIPPLE REJECTION vs. FREQUENCY
MAX1615-05
1.6
SHUTDOWN SUPPLY CURRENT (µA)
1.4
1.2
1.0
0.8
0.6
0.4
0.2
0
4
8
12
16
20
24
-70
-60
RIPPLE REJECTION (dB)
-50
-40
-30
-20
-10
I
LOAD
= 10mA
0
28
0.01
0.1
1
FREQUENCY (kHz)
10
100
SUPPLY VOLTAGE (V)
TIME TO EXIT SHUTDOWN
MAX1615-06
LINE-TRANSIENT RESPONSE
MAX1615-07
LOAD-TRANSIENT RESPONSE
MAX1615-08
+5V
SHDN
0V
+20V
C
IN
10µF
V
IN
+10V
V
OUT
50mV/div
C
OUT
4.7µF
V
OUT
50mV/div
+5V
OUT
0V
V
IN
= 10V
500µs/div
50µs/div
100µs/div
I
OUT
30mA/div
DROPOUT SUPPLY CURRENT
vs. SUPPLY VOLTAGE
80
70
V
IN
- V
OUT
(V)
60
50
40
30
20
10
0
4.0 4.2 4.4 4.6 4.8 5.0 5.2 5.4 5.6 5.8 6.0
SUPPLY VOLTAGE (V)
0
0
5
T
A
= -40°C
T
A
= +25°C
T
A
= 0°C
0.20
0.15
0.10
0.05
T
A
= +85°C
MAX1615-09
DROPOUT VOLTAGE
vs. LOAD CURRENT
MAX1615-10
90
DROPOUT SUPPLY CURRENT (µA)
0.30
0.25
10
15
20
25
30
35
40
LOAD CURRENT (mA)
4
_______________________________________________________________________________________
High-Voltage, Low-Power Linear Regulators
for Notebook Computers
______________________________________________________________Pin Description
PIN
MAX1615
1
2
3
4
—
5
MAX1616
1
2
3
—
4
5
NAME
IN
GND
OUT
5/3
FB
SHDN
FUNCTION
Positive Input Voltage. Connect to a +4V to +28V supply.
Ground
Regulator Output
Preset Output Voltage Select. Connect to GND for 3.3V output or to OUT
for 5.0V output.
Feedback Input. Regulates to 1.24V nominally.
Shutdown, active low input. Connect to IN for automatic start up.
MAX1615/MAX1616
IN
VREF
The MAX1615’s output voltage is fed back through an
internal resistor voltage divider connected to OUT. Set
the output voltage to either 3.3V or 5.0V with the 5/3 pin.
Select the 5V output by connecting 5/3 to OUT, or the
3.3V output by connecting 5/3 to GND.
OUT
CURRENT
LIMIT
SHDN
The MAX1616 uses external feedback, allowing the out-
put voltage to be set by external resistors (see
Setting
the MAX1616 Output Voltage
section). The typical FB
threshold is at 1.24V.
MAX1615
MAX1616
Shutdown
The device enters shutdown mode when
SHDN
is low.
In shutdown mode, the pass transistor, control circuit,
reference, and all biases turn off, reducing the supply
current to below 1µA. Connect
SHDN
to IN for automatic
start-up.
Current Limit
Output current is limited to 100mA (typical). The current
limit exceeds the 30mA (max) safe operating limit. The
output can be shorted to ground for 30 seconds without
damaging the part.
FB
(MAX1616)
5/3
(MAX1615)
GND
Thermal-Overload Protection
When the junction temperature exceeds T
J
= +150°C,
the thermal sensor sends a signal to the shutdown
logic, turning off the pass transistor and allowing the IC
to cool. The thermal sensor turns the pass transistor on
again after the IC’s junction temperature cools by
+20°C (typical), resulting in a pulsating output during
continuous thermal-overload conditions.
Figure 1. Functional Diagram
_______________Detailed Description
The MAX1615/MAX1616 low-quiescent-current linear
regulators are designed primarily for high input voltage
applications. The MAX1615 supplies a preselected 3.3V
or 5.0V output for loads up to 30mA. The MAX1616
provides an adjustable voltage from 1.24V to 28V. The
maximum output current is a function of the package’s
maximum power dissipation for a given temperature. A
5µA load is required to maintain output regulation.
Operating Region and Power Dissipation
Maximum power dissipation depends on the thermal
resistance of the case and circuit board, the tempera-
ture difference between the die junction and ambient
air, and the rate of air flow. The device’s power dissipa-
5
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