19-3329; Rev 3; 3/10
KIT
ATION
EVALU
BLE
AVAILA
High-Efficiency LCD Boost
with True Shutdown
General Description
Features
♦
15V or Adjustable Output Voltage Up to 28V
♦
Safety Features Protect Against Output Faults
♦
20mA at 20V from a Single Li+ Battery
♦
♦
♦
♦
True Shutdown
87% Efficiency
Up to 800kHz Switching Frequency
Small, 6-Pin SOT23 and
µDFN
(MAX8570 Only)
Packages
MAX8570–MAX8575
The MAX8570 family of LCD step-up converters uses
an internal n-channel switch and an internal p-channel
output isolation switch. These converters operate from
a 2.7V to 5.5V supply voltage and deliver up to 28V at
the output.
A unique control scheme provides the highest efficien-
cy over a wide range of load conditions. The internal
MOSFET switch reduces external component count and
a high switching frequency (up to 800kHz) allows for
tiny surface-mount components. Three current-limit
options are available. The MAX8570 and MAX8572 use
a 110mA current limit to reduce ripple and component
size in low-current applications. For high-power require-
ments, the MAX8574 and MAX8575 use a 500mA cur-
rent limit and supply up to 20mA at 20V. The MAX8571
and MAX8573 use a 250mA current limit for a compro-
mise between ripple and power. Built-in safety features
protect the internal switch and down-stream compo-
nents from fault conditions.
Additional features include a low quiescent current and
a True Shutdown™ mode to save power. The MAX8570/
MAX8571/MAX8574 allow the user to set the output
voltage between 3V and 28V, and the MAX8572/
MAX8573/MAX8575 have a preset 15V output. These
step-up converters are ideal for small LCD panels with
low current requirements, but can also be used in other
applications. The MAX8571 evaluation kit is available to
help reduce design time.
Ordering Information
PART
MAX8570ELT+T
MAX8570EUT+T
MAX8571EUT+T
MAX8572EUT+T
MAX8573EUT+T
MAX8574EUT+T
TEMP RANGE
-40°C to +85°C
-40°C to +85°C
-40°C to +85°C
-40°C to +85°C
-40°C to +85°C
-40°C to +85°C
PIN-
PACKAGE
6L μDFN
6 SOT23
6 SOT23
6 SOT23
6 SOT23
6 SOT23
TOP
MARK
ACW
ABTJ
ABTK
ABTL
ABTM
ABTN
ABTO
MAX8575EUT+T
-40°C to +85°C
6 SOT23
+Denotes
a lead(Pb)-free RoHS-compliant package.
T = Tape and reel.
Applications
LCD Bias Generators
Polymer LEDs (OLED)
Cellular or Cordless Phones
Palmtop Computers
Personal Digital Assistants (PDAs)
Organizers
Handy Terminals
PART
MAX8570
MAX8571
MAX8572
MAX8573
MAX8574
MAX8575
110mA
250mA
110mA
250mA
500mA
500mA
Selector Guide
CURRENT LIMIT
OUTPUT VOLTAGE
Adjustable
Adjustable
15V
15V
Adjustable
15V
Pin Configurations
TOP VIEW
+
FB 1
GND 2
SHDN 3
6
V
CC
SW
LX
Typical Operating Circuit
V
OUT
= V
CC
TO 28V
SW
LX
MAX8570
MAX8571
MAX8574
5
4
V
CC
= 2.7V TO 5.5V
V
CC
MAX8572
MAX8573
MAX8575
OUT
SOT23
Pin Configurations continued at end of data sheet.
True Shutdown is a trademark of Maxim Integrated Products, Inc.
ON
OFF
SHDN
GND
________________________________________________________________
Maxim Integrated Products
1
For pricing, delivery, and ordering information, please contact Maxim Direct at 1-888-629-4642,
or visit Maxim’s website at www.maxim-ic.com
High-Efficiency LCD Boost
with True Shutdown
MAX8570–MAX8575
ABSOLUTE MAXIMUM RATINGS
V
CC
,
SHDN
to GND ..................................................-0.3V to +6V
SW to GND .................................................-0.3V to (V
CC
+ 0.3V)
FB to GND (MAX8570/MAX8571/
MAX8574)...............................................-0.3V to (V
CC
+ 0.3V)
OUT to GND (MAX8572/MAX8573/MAX8575) .......-0.3V to +30V
LX to GND ..............................................................-0.3V to +30V
I
LX
, I
CC
..............................................................................600mA
Continuous Power Dissipation (T
A
= +70°C)
μDFN (derate 4.5mW/°C above +70°C)....................357.8mW
SOT23-6 (derate 8.7mW/°C above +70°C)...............695.7mW
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
Soldering Temperature (reflow) .......................................+260°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
(V
CC
= V
SHDN
= 3.6V, SW open, V
FB
= 1.3V (MAX8570/MAX8571/MAX8574) or V
OUT
= 16V (MAX8572/MAX8573/MAX8575), T
A
=
-40°C to +85°C, unless otherwise noted. Typical values are at T
A
= +25°C.) (Note 1)
PARAMETER
V
CC
Input Voltage Range
V
CC
Undervoltage Lockout
V
CC
Supply Current
V
CC
Shutdown Current
Line Regulation
Load Regulation
FB Regulation Voltage
FB Input Bias Current
OUT Regulation Voltage
OUT Input Bias Current
LX Voltage Range
MAX8571/MAX8573
LX Switch Current Limit (Note 2)
MAX8570/MAX8572
MAX8574/MAX8575
LX On-Resistance
LX Leakage Current
Maximum LX On-Time
Minimum LX Off-Time
Current-Limit Propagation Delay
SHDN
Low Level (V
IL
)
SHDN
High Level (V
IH
)
SHDN
Leakage Current
2.7V
≤
V
CC
≤
5.5V
4.2V
≤
V
CC
≤
5.5V
2.7V
≤
V
CC
< 4.2V
1.5
1.4
-1
+1
V
FB
> 1V or V
OUT
> 12.2V
V
FB
= 0.25V or V
OUT
= 3.4V
MAX8571/MAX8573/MAX8574/MAX8575, I
LX
= 100mA
MAX8570/MAX8572, I
LX
= 50mA
V
LX
= 28V
T
A
= +25°C
T
A
= -40°C to +85°C
8
0.8
4.0
0.217
0.088
0.425
0.241
0.101
0.484
0.9
1.5
0.01
0.05
11
1
5
55
0.7
14
1.2
6.0
T
A
= 0°C to +85°C
T
A
= -40°C to +85°C
V
OUT
= 15V
SHDN
= GND, V
CC
= 5.5V
T
A
= +25°C
T
A
= -40°C to +85°C
V
CC
rising, 50mV typical hysteresis
CONDITIONS
MIN
2.70
2.33
2.5
25
0.05
0.05
0.1
0.1
1.216
1.2137
-50
14.85
14.813
2.4
-4
15
1.226
1.236
1.2383
+50
15.15
15.187
4.4
28
0.267
0.108
0.540
1.5
2.4
2
Ω
μA
μs
μs
ns
V
V
μA
A
TYP
MAX
5.50
2.65
35
1
UNITS
V
V
μA
μA
%/V
%/mA
V
nA
V
μA
V
Circuit of Figure 3, V
OUT
= 15V, I
LOAD
= 5mA,
V
CC
= 2.7V to 5.5V
Circuit of Figure 3, V
OUT
= 15V, I
LOAD
= 0 to 5mA
T
A
= 0°C to +85°C
T
A
= -40°C to +85°C
2
_______________________________________________________________________________________
High-Efficiency LCD Boost
with True Shutdown
ELECTRICAL CHARACTERISTICS (continued)
(V
CC
= V
SHDN
= 3.6V, SW open, V
FB
= 1.3V (MAX8570/MAX8571/MAX8574) or V
OUT
= 16V (MAX8572/MAX8573/MAX8575), T
A
=
-40°C to +85°C, unless otherwise noted. Typical values are at T
A
= +25°C.) (Note 1)
PARAMETER
SW PMOS Current Limit
SW PMOS On-Resistance
SW PMOS Leakage Current
SW Soft-Start Time
CONDITIONS
V
CC
= 3.6V, V
SW
= 0V, V
FB
= 0V, I
CC
(peak)
V
CC
= 3.6V, V
SW
= 0V, V
FB
= 0V, I
CC
(average)
V
CC
= 2.7V, V
FB
= 0V, I
SW
= 100mA
SW = GND, V
CC
= 5.5V, V
FB
= 0V
V
CC
= 2.7V, C
SW
= 4.7μF
T
A
= +25°C
T
A
= -40°C to +85°C
MIN
0.45
0.15
TYP
0.75
0.30
1.5
0.01
0.02
0.2
1
MAX
1.10
0.60
2.5
1
UNITS
A
Ω
μA
ms
MAX8570–MAX8575
Note 1:
Parameters are production tested at T
A
= +25°C. Limits over temperature are guaranteed by design.
Note 2:
Specified currents are measured at DC. Actual LX current limits are slightly higher in circuit due to current-limit comparator
delay. Actual currents (with 2μH) are 110mA (MAX8570/MAX8572), 250mA (MAX8571/MAX8573), and 500mA
(MAX8574/MAX8575).
Typical Operating Characteristics
(MAX8571, V
CC
= 3.6V, V
OUT
= 18V, Circuit of Figure 2, T
A
= +25°C, unless otherwise noted.)
OUTPUT VOLTAGE
vs. SUPPLY VOLTAGE (MAX8571)
MAX8570/71/73/74/75 toc01
OUTPUT VOLTAGE
vs. SUPPLY VOLTAGE (FIGURE 3, MAX8573)
MAX8570/71/73/74/75 toc02
OUTPUT VOLTAGE
vs. SUPPLY VOLTAGE (MAX8574)
18.8
18.6
OUTPUT VOLTAGE (V)
18.4
18.2
18.0
17.8
17.6
17.4
L1 = TOKO S1024-100M
R1 = 1.1MΩ, R2 = 75kΩ, C4 = 4.7pF
3.1
3.4
3.7
4.0
4.3
4.6
4.9
20mA LOAD
MAX8570/71/73/74/75 toc03
18.5
18.4
18.3
OUTPUT VOLTAGE (V)
18.2
18.1
18.0
17.9
17.8
17.7
17.6
17.5
L1 = MURATA LQH32CN220K23
R1 = 3.9MΩ, R2 = 287kΩ
2.7
3.1
3.5
3.9
4.3
4.7
5.1
1mA LOAD
5mA LOAD
15.5
15.4
15.3
OUTPUT VOLTAGE (V)
15.2
15.1
15.0
14.9
14.8
14.7
14.6
14.5
L1 = MURATA LQH32CN220K23
2.7
3.1
3.5
3.9
4.3
4.7
5.1
5mA LOAD
1mA LOAD
19.0
5mA LOAD
17.2
17.0
5.5
5.5
SUPPLY VOLTAGE (V)
SUPPLY VOLTAGE (V)
SUPPLY VOLTAGE (V)
OUTPUT VOLTAGE
vs. LOAD CURRENT
MAX8570/71/73/74/75 toc04
OUTPUT VOLTAGE vs. TEMPERATURE
MAX8570/71/73/74/75 toc05
EFFICIENCY vs. SUPPLY VOLTAGE
MAX8570/71/73/74/75 toc06
19.0
18.8
OUTPUT VOLTAGE (V)
18.6
18.4
18.2
18.0
17.8
17.6
17.4
0
L1 = MURATA LQH32CN220K23
MAX8574, R1 = 1.1MΩ, R2 = 75kΩ, C4 = 4.7pF
18.4
18.3
18.2
OUTPUT VOLTAGE (V)
18.1
18.0
17.9
17.8
17.7
100
95
EFFICIENCY (%)
90
85
80
22μH, 5mA LOAD
75
22μH, 1mA LOAD
L1 = TOKO A914BYW-470M
47μH, 5mA LOAD
47μH, 1mA LOAD
MAX8570
MAX8571
17.6
20
25
1mA LOAD
-40
-15
10
35
60
85
L1 = MURATA LQH32CN220K23
R1 = 3.9MΩ, R2 = 287kΩ, C4 = 10pF
5
10
15
70
2.7
3.1
3.5
3.9
4.3
4.7
5.1
5.5
TEMPERATURE (°C)
SUPPLY VOLTAGE (V)
LOAD CURRENT (mA)
_______________________________________________________________________________________
3
High-Efficiency LCD Boost
with True Shutdown
MAX8570–MAX8575
Typical Operating Characteristics (continued)
(MAX8571, V
CC
= 3.6V, V
OUT
= 18V, Circuit of Figure 2, T
A
= +25°C, unless otherwise noted.)
EFFICIENCY vs. BATTERY VOLTAGE
(FIGURE 4)
MAX8570/71/73/74/75 toc07
EFFICIENCY vs. LOAD CURRENT
WITH 22μH INDUCTOR
MAX8570/71/73/74/75 toc08
EFFICIENCY vs. LOAD CURRENT
WITH 47μH INDUCTOR
MAX8570, L1 = MURATA LQH32CN470K23
90
EFFICIENCY (%)
80
70
60
50
40
MAX8571, L1 = TOKO A914BYW-470M
MAX8570/71/73/74/75 toc09
100
5mA LOAD
90
EFFICIENCY (%)
80
1mA LOAD
70
60
50
40
0
V
CC
= 3.6V
L1 = MURATA LQH32CN220K23
100
90
EFFICIENCY (%)
80
70
60
50
40
MAX8571, MURATA LQH32CN220K23
MAX8574, TOKO A914BYW-220M
MAX8570, MURATA LQH32CN220K23
100
2
4
6
8
10
12
0.1
1
10
100
0.1
1
10
100
BATTERY VOLTAGE (V)
LOAD CURRENT (mA)
LOAD CURRENT (mA)
PEAK INDUCTOR CURRENT LIMIT
vs. SUPPLY VOLTAGE
MAX8570/71/73/74/75 toc10
SUPPLY CURRENT vs. LOAD CURRENT
MAX8570/71/73/74/75 toc11
NO-LOAD CURRENT vs. SUPPLY VOLTAGE
70
SUPPLY CURRENT (μA)
60
50
40
30
20
MAX8573,
FIGURE 3
R1 = 7.87MΩ
R2 = 576kΩ
R1 = 3.9MΩ
R2 = 287kΩ
MAX8570/71/73/74/75 toc12
700
600
CURRENT LIMIT (mA)
500
400
300
200
100
0
2.7
3.1
3.5
3.9
4.3
4.7
5.1
MAX8570
MAX8571
MAX8574
120
100
SUPPLY CURRENT (mA)
80
60
40
20
0
L1 = MURATA LQH32CN220K23
0
5
10
80
10
0
15
0
L1 = MURATA
LQH32CN220K23
1
2
3
NO SWITCHING
5.5
4
5
6
SUPPLY VOLTAGE (V)
LOAD CURRENT (mA)
SUPPLY VOLTAGE (V)
LINE TRANSIENT 3V TO 5.5V (MAX8571)
MAX8570/71/73/74/75 toc13
LINE TRANSIENT 3V TO 5.5V
(FIGURE 3, MAX8573)
MAX8570/71/73/74/75 toc14
V
OUT
200mV/div
(AC-COUPLED)
V
OUT
200mV/div
(AC-COUPLED)
V
CC
2V/div
V
CC
2V/div
0
100μs/div
3.6kΩ LOAD, R1 = 3.9MΩ, R2 = 287kΩ
3kΩ LOAD
100μs/div
0
4
_______________________________________________________________________________________
High-Efficiency LCD Boost
with True Shutdown
Typical Operating Characteristics (continued)
(MAX8571, V
CC
= 3.6V, V
OUT
= 18V, Circuit of Figure 2, T
A
= +25°C, unless otherwise noted.)
MAX8570–MAX8575
LOAD TRANSIENT
MAX8570/71/73/74/75 toc15
STARTUP AND SHUTDOWN WAVEFORMS
MAX8570/71/73/74/75 toc16
V
OUT
V
SHDN
100mV/div
(AC-COUPLED)
BOOST SOFT-START
SW TURN-ON
V
OUT
5mA/div
5V/div
10V/div
0
I
OUT
0
I
LX
200mA/div
0
400µs/div
1.8Ω LOAD
100µs/div
Pin Description
PIN
MAX8570
(µDFN)
MAX8570/ MAX8572/
MAX8571/ MAX8573/
MAX8574 MAX8575
(SOT23)
(SOT23)
1
—
NAME
FUNCTION
3
FB
Feedback for Setting the Output Voltage. Connect FB to the center of a resistor
voltage-divider from the output to GND to set positive output voltages.
Output. The output voltage is preset to 15V. Connect a 1µF ceramic capacitor
from OUT to GND. In shutdown, OUT is pulled to GND by an internal 7.5MΩ
resistor.
Ground
Shutdown Input. A logic-low at
SHDN
places the part in low-power shutdown
mode. Pull
SHDN
high or connect to V
CC
for normal operation.
Inductor Switching Connection
Isolation Switch Output. Internally connected to the drain of a p-channel
MOSFET used to isolate the output from the input during shutdown. Connect a
4.7µF ceramic capacitor from SW to GND. If True Shutdown is not required, SW
can be left open with the input supply connected directly to the inductor.
Input Voltage Supply. Connect a 2.7V to 5.5V input supply to V
CC
. Connect a
1µF ceramic capacitor from V
CC
to GND.
—
2
1
6
—
2
3
4
1
2
3
4
OUT
GND
SHDN
LX
5
5
5
SW
4
6
6
V
CC
_______________________________________________________________________________________
5
京公网安备 11010802033920号
EEWORLD
