AMS AMS1027

AMS1027
DESCRIPTION
FEATURES
The AMS1027 is a 5-pin thin SOT23 current
mode step up converter intended for small, low
power applications. The AMS1027 switches at
1.3MHz and allows the use of tiny, low cost
capacitors and inductors 2mm or less in height.
Internal soft start results in small inrush current
and extends battery life.The AMS1027 operates
from an input voltage as low as 2.5V and can
generate 12V at up to 200mA from a 5V supply.
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The AMS1027 includes under-voltage lockout,
current limiting, and thermal overload protection
to prevent damage in the event of an output
overload. The AMS1027 is available in a small
5-pin SOT23 package.
On Board Power MOSFET
Uses Tiny Capacitors and Inductors
1.3MHz Fixed Switching Frequency
Internally Compensated
Internal Soft-Start
Operates with Input Voltage as Low as 2.5V
and Output Voltage as High as 22V
12V at 200mA from 5V Input
UVLO, Thermal Shutdown
Internal Current Limit
Available in a SOT23-5 Package
APPLICATIONS
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Camera Phone Flash
Handheld Computers and PDAs
Digital Still and Video Cameras
External Modems
Small LCD Displays
White LED Driver
TYPICAL APPLICATION
D1
VIN
5V
5
OFF ON
IN
4
EN
2
1
SW
AMS1027
GND
VOUT
12V
200mA
FB
3
Vout=1.25(1+R1/R2) (V)
1
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AMS1027
PACKAGE REFERENCE
TOP VIEW
SW
1
GND
2
FB
3
5
IN
4
EN
ABSOLUTE MAXIMUM RATINGS
SW Pin ...........................................–0.5V to 25V
All Other Pins ................................–0.3V to 6.5V
Lead Temperature ....................................260°C
Storage Temperature.............. –65°C to +150°C
Recommended Operating Conditions
Supply Voltage VIN .............................2.5V to 6V
Output Voltage VOUT ............................Vin to 22V
Operating Temperature............. –40°C to +85°C
Functional Block Diagram
SW
1
FB
3
-
+
CONTROL
LOGIC
+
1.25V
ERROR
AMPLIFIER
PWM
COMPARATOR
+
+
-
CURRENT
SENSE
AMPLIFIER
1.3MHz
OSC
2
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2
GND
AMS1027
PIN FUNCTIONS
Pin #
Name Function
Power Switch Output. SW is the drain of the internal MOSFET switch. Connect the power
inductor and output rectifier to SW. SW can swing between GND and 22V.
1
SW
2
GND
3
FB
Feedback Input. FB voltage is 1.25V. Connect a resistor divider to FB.
4
EN
Regulator On/Off Control Input. A high input at EN turns on the converter, and a low input turns
it off. When not used, connect EN to the input source for automatic startup. The EN pin cannot
be left floating.
5
IN
Input Supply Pin. Must be locally bypassed.
Ground.
ELECTRICAL CHARACTERISTICS
VIN = VEN = 5V, TA = +25°C unless otherwise specified.
Parameters
Symbol
Operating Input Voltage
Condition
VIN
Min
Typ
2.5
Undervoltage Lockout
2.25
Undervoltage Lockout
Hysteresis
92
Max
Units
6
V
2.45
V
mV
Supply Current (Shutdown)
VEN = 0V
0.1
1
µA
Supply Current (Quiescent)
VFB = 1.3V
635
850
µA
1.0
1.3
1.5
MHz
Switching Frequency
fSW
Maximum Duty Cycle
VFB = 0V
85
92
EN Threshold
VEN Rising
1.1
1.35
EN Threshold
VEN Rising, VIN = 2.5V
0.8
EN Hysteresis
VEN = 0V, 5V
EN Input Bias Current
FB Voltage
VFB
FB Input Bias Current
SW On-Resistance
VFB = 1.25V
1.6
V
V
90
mV
1
µA
1.21
1.25
–100
–30
nA
0.5
Ω
1.9
A
RDS (ON)
SW Current Limit
SW Leakage
%
VSW = 15V
Thermal Shutdown
1
160
3
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1.29
V
µA
°C
AMS1027
TYPICAL APPLICATION CIRCUITS
V IN = 5V, VOUT = 12V, IOUT = 200mA Boost Circuit
D1
MBR0520L
VIN
5V
5
OFF ON
4
2
IN
EN
1
C3
100pF
SW
AMS1027
GND
VOUT
12V
200mA
FB
3
4
Advanced Monolithic Systems http://www.ams-semitech.com
AMS1027
PACKAGE INFORMATION
SOT23-5
2.80
3.00
5
4
1.50
1.70
2.60
3.00
0.09
0.20
SIDE VIEW
1
3
TOP VIEW
0.84
0.90
1.00 MAX
SEATING PLANE
0.30
0.50
0.95 BSC
0.00
0.10
NOTE:
FRONT VIEW
ALL DIMENSIONS ARE IN MILLIMETERS.
5
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