Page 1 of 11 V 0.2
AAT1500
Product information presented is current as of publication date. Details are subject to change without notice
CONSTANT CURRENT BOOST CONVERTER
FOR 1 TO 4 WHITE LEDS
Features
Up to 4 LEDs at 2.8V Supply
High Efficiency (85%)
Output Over Voltage Protection
HV Internal Switch
1 MHz PWM Switching Frequency
Uses Tiny 1 mm Height Inductor
2.6V to 6V Input Range
0.1A Shutdown Current
SOT-26 & VQFN-8 Package Available
Pin Configuration
General Description
The AAT1500 is a step-up converter that provides a
solution to drive 1 to 4 white LEDs with a constant
current from a Lithium Ion cell, and its switching
frequency is fixed at 1 MHz.
The AAT1500 offers a low 0.25V reference, which
minimizes power loss in the current setting resistor
and improves efficiency. Protection feature includes
output over voltage protection. The AAT1500
consists of a 0.1A shutdown current, and HV
internal switch. Input supple range allows operation
from 2.6V to 6V.
The AAT1500 is available in 6-pin SOT-26 and
8-pin VQFN-8 package.
Applications
Palmtops
MP3 Player
Digital Still Cameras
Portable Media Player
Cell Phones and Smart Phones
Electronic Information Organizers
TOP
VIEW
SOT-26 PACKAGE
SW
GND
IE
EN
OVP
VDD
1
2
3
4
5
6
TOP
VIEW
SOT-26 PACKAGE
SW
GND
IE
EN
OVP
VDD
1
2
3
4
5
6
TOP
VIEW
VQFN-8 PACKAGE
SW
GND
IE
EN
OVP
VDD
1
2
3
4
5
6
7
8
NC
GND1
TOP
VIEW
VQFN-8 PACKAGE
SW
GND
IE
EN
OVP
VDD
1
2
3
4
5
6
7
8
NC
GND1
Page 2 of 11 V 0.2
AAT1500
Pin Description
PIN NO
SOT-26
PIN NO
VQFN-8
NAME
I/O
DESCRIPTION
1
8
SW
O
Switch Pin
2
4
GND
-
Ground
3
6
IE
I
Inverting Input Pin of Error Amplifier
4
3
EN
I
Chip Enable/Disable(Active High)
5
1
OVP
I
Over Voltage Protection
6
2
VDD
-
Supply Voltage
-
7
GND1
-
SW MOS Ground
-
5
NC
-
NC
Absolute Maximum Ratings
(Note 1)
CHARACTERISTICS
SYMBOL
VALUE
UNIT
Supply Voltage
DD
V
3
.
0 to 7
V
SW, OVP to GND
3
.
0 to 21
V
Other I/O Pin Voltage
3
.
0 to 6
V
Junction Temperature
125
o
C
Storage Temperature Range
storage
T
45 to 125
o
C
Operating Temperature Range
C
T
40 to 85
o
C
Lead Temperature
L
T
260
o
C
Recommended Operating Conditions
CHARACTERISTICS
SYMBOL
VALUE
UNIT
Supply Voltage
DD
V
2.6 to 6
V
Dissipation Ratings
CHARACTERISTICS
PACKAGE SYMBOL
VALUE
UNIT
SOT-26
JA
208
o
C/W
Package Thermal Resistance
VQFN-8
JA
50
o
C/W
SOT-26
d
P
0.48
W
Power Dissipation,
C
T = 25
o
C
VQFN-8
d
P
2
W
Page 3 of 11 V 0.2
AAT1500
Electrical Characteristics, V
DD
= 3.6 V, T
C
= 25
o
C (Unless Otherwise Specified)
Operating Condition
PARAMETER
SYMBOL TEST CONDITION
MIN TYP MAX UNIT
Supply Voltage
DD
V
2.6
6.0
V
Under Voltage Lockout
UVLO
V
1.8
2.2
2.3
V
Operating Current
DD
I
DD
V
= 5.5V, Switch On
2
mA
Quiescent Current
Q
I
DD
V
= 5.5V
FB
V
= 1.3V, Switch Off
250
500
A
Shutdown Current
SD
I
DD
V
= 5.5V,
EN
V < 0.4V
0.1
1
A
Oscillator
PARAMETER
SYMBOL TEST CONDITION
MIN TYP MAX UNIT
Operating Frequency
OSC
f
0.8
1.0
1.2 MHz
Maximum Duty Cycle
MAX
D
79
85
92
%
Reference Voltage
PARAMETER
SYMBOL TEST CONDITION
MIN TYP MAX UNIT
Feedback Voltage
IE
V
Note 2
0.237 0.250 0.263
V
N-Channel Switch
PARAMETER
SYMBOL TEST CONDITION
MIN TYP MAX UNIT
Current Limit
LIM
I
0.60
0.75 0.90
A
On-Resistance
ON
R
0.50
0.75 1.00
Leakage Current
SWOFF
I
SW
V = 12V
0.01 20.00 A
Control and Protection
PARAMETER
SYMBOL TEST CONDITION
MIN TYP MAX UNIT
EN pin Current
EN
I
4
6
A
OVP Threshold
OVP
V
14.5
15.5 20.0
V
ENH
V
Chip Enable
0.8
1.4
V
Chip Enable/Disable
ENL
V
Chip Disable
0.4
0.8
V
Page 4 of 11 V 0.2
AAT1500
Note 1.
Stresses beyond those listed under "Absolute Maximum Ratings" may cause permanent damage to
the device. Exposure to absolute maximum rating conditions for extended period of time may
affect device reliability.
Note 2.
To measure the feedback voltage, the device
IE
V
would connect to the application circuit. The
inductance is 10 H and the output voltage equals 12V.
Block Diagram
SOT-26 and VQFN-8
Bandgap
Soft-Start
VBG
Current Sense
Control
Logic
Driver
Oscillator
IE
GND/
GND1
SW
EN
VDD
0.25V
0.25V
VBG
OVP
UVLO
OVP
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