Advanced Analog Technology, Inc.
AAT1109
Details are subject to change without notice.
ONE-CHANNEL STEP-UP PWM CONTROLLER
FEATURES
Under-Voltage Lockout (UVLO) Protection
Totem Pole Output
Output Short Circuit Protection
Soft-Start Function
Wide Operating Frequency：
10 kHz to 1MHz
Shutdown Control
Low Dissipation Current :
Typical
1.6mA
in Operation
SOP-8 & TSSOP-8 Package Available
GENERAL DESCRIPTION
The AAT1109 is a one-channel step-up PWM
controller incorporating a soft-start and a short
circuit protection (SCP) function.
This device consists of an on-chip voltage reference,
error amplifier, pulse width modulation controller,
under-voltage lockout protection, soft-start, and
short circuit protection circuits. Switching
frequency up to 1MHz is set by an external resistor
and capacitor. Soft-start time can be implemented
by the SCP capacitor.
Additionally, a chip-enable feature is also provided
to power down and reduce the current supply
to
10µA
. With the minimal external components,
the AAT1109 offers a simple and economical
solution.
PIN CONFIGURATION
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AAT1109
PIN DESCRIPTION
PIN NO.
1
2
3
4
5
6
7
8
NAME I/O
DESCRIPTION
CE
I Chip Enable Input Pin（Internal Pull "H"）
SCP
I Soft-Start and SCP Capacitor Connection Pin
V
DD
- Power Supply
OUT
O Totem Pole Type Output Pin
GND
- Ground
OSC
O Capacitor and Resistor Connection Pin for Setting the Oscillation Frequency
OE
O Output Pin of Error Amplifier
I Inverting Input Pin of Error Amplifier
IE
ABSOLUTE MAXIMUM RATINGS
CHARACTERISTICS
Supply Voltage
Output Current
Operating Free-Air Temperature Range
Storage Temperature Range
Power Dissipation
SYMBOL
V
DD
VALUE
7
−
120 /
+
120
−
20
to
+
85
−
45
to
+
125
UNIT
V
mA
o
o
I
O
T
C
T
storage
C
P
d
500
C
mW
RECOMMENDED OPERATING CONDITIONS
Supply Voltage
Error Amplifier Input Voltage
Oscillator (OSC) Capacitance
Oscillator (OSC) Resistance
Oscillator (OSC) Frequency
Output Current
Operating Free-Air Temperature
SYMBOL
V
DD
V
I
C
OSC
MIN
2.6
0.5
MAX
6.5
1.6
UNIT
V
V
pF
k
Ω
100
1.0
10
−
20
10,000
10.0
1,000
+
30 /
−
30
+
85
R
OSC
f
OSC
I
O
T
C
kHz
mA
o
C
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AAT1109
ELECTRICAL CHARACTERISTICS,
V
DD
= 3.3V (UNLESS OTHERWISE
SPECIFIED) (SEE NOTE 1)
OSCILLATOR
PARAMETER
SYMBOL
Oscillation Frequency
Frequency Variation with
Temperature
Frequency Input Stability
f
OSC
f
∆
T
f
∆
V
TEST CONDITION
C
OSC
=270pF
R
OSC
=
4.2kΩ
MIN TYP MAX UNIT
400
500
5
1
600
kHz
%
%
T
C
= −
20
o
C to
+
85 C
V
DD
=
2.6V to 6.5V
o
UNDER-VOLTAGE PROTECTION
PARAMETER
TEST CONDITION
Upper Threshold Voltage
Lower Threshold Voltage
Hysteresis
(
V
UPH
−
V
UPL
)
V
UPH
V
UPL
V
HYS
T
C
=
25
o
C
T
C
=
25
o
C
T
C
=
25
o
C
=
25
o
C
.
MIN TYP MAX UNIT
V
2.12 2.47 2.85
1.96 2.28
0.19
2.63
V
V
Note 1: Typical values of all parameters are specified at
T
C
SHORT CIRCUIT PROTECTION CONTROL
PARAMETER
TEST CONDITION
MIN TYP MAX UNIT
Input Threshold Voltage
Short-Circuit Detection
Threshold Voltage
Charging Current
V
r1
V
r 2
I
SCP
V
SCP
=
0V
1.160 1.262 1.360
1.160 1.262 1.360
−
2.15
−
1.50
−
1.00
V
V
µ
A
SOFT-START
PARAMETER
Charging Current
Voltage at Soft-Start
Completion
I
CS
V
ts
TEST CONDITION
V
SCP
=
0V
MIN TYP MAX UNIT
−
2.15
−
1.50
−
1.00 µA
1.160 1.262 1.360
V
SHUTDOWN CONTROL
PARAMETER
TEST CONDITION
MIN TYP MAX UNIT
Shutdown Enable Voltage
Shutdown Release Voltage
V
SE
V
SR
2.0
0.5
V
V
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Advanced Analog Technology, Inc.
AAT1109
ELECTRICAL CHARACTERISTICS,
V
DD
= 3.3V (UNLESS OTHERWISE
SPECIFIED (SEE NOTE 1)
IDLE PERIOD ADJUSTMENT SECTION
PARAMETER
Maximum Duty Cycle
t
Duty
TEST CONTION
MIN TYP MAX UNIT
,
C
OSC
=
270pF
75
85
93
%
R
OSC
=
4.2k
Ω
,
V
OE
=
1.12V
EA (ERROR AMPLIFIER)
PARAMETER
Input Threshold Voltage
V
T
V
T
∆
V
V
T
∆
T
TEST CONDITION
V
OE
=
0.7V
MIN
TYP MAX UNIT
1.249 1.262 1.275
2
1
0.1
1.4
1.7
0.05
0.20
20
−
75
V
mV
V
T
Input Stability
V
T
Variation with
Temperature
Input Bias Current
Output Voltage Swing
Output Sink Current
Output Source Current
Open-Loop Voltage Gain
V
DD
=
2.6 to 6.5V
T
C
= −
20
o
C to
+
85
o
C
8
%
1.0
µ
A
I
B
V
OS
+
V
OS
−
I
OS
+
I
OS
−
A
VO
V
OE
=
0.7V
V
OE
=
0.7V
V
mA
µ
A
3
−
45
70
85
dB
OUTPUT SECTION
PARAMETER
TEST CONDITION
TYP MAX UNIT
High-Level Output Voltage
Low-Level Output Voltage
Rise Time
Fall Time
V
OH
V
OL
t
RISE
I
o
= −
30mA
I
o
= +
30mA
C
L
=
1,000pF
1.9
2.3
0.8
100
1.2
V
V
ns
ns
t
FALL
C
L
=
1,000pF
100
OPERATING CURRENT
PARAMETER
TEST CONDITION
MIN
TYP MAX UNIT
Supply Current
I
DD
−
OFF
I
DD
−
ON
Output ”OFF” State
R
OSC
=
4.2k
Ω
1.3
1.6
mA
mA
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Advanced Analog Technology, Inc.
AAT1109
HOW TO SET THE TIME CONSTANT FOR SOFT-START AND SHORT
CIRCUIT PROTECTION
1. Soft-Start
AAT1109 operates in soft-start mode. The PWM comparator monitors the voltage at soft-start setting
and SCP pin, which varies proportionally to each other. This proportion relation controls the ON duty
of the OUT pin and activates the soft-start operation. In the Soft-start mode, the voltage at SCP pin
( V
SCP
) is input to the PWM comparator, so that the ON duty of the OUT pin is determined by the V
SCP
.
When the soft-started mode is completed, its setting voltage remains high and the circuit enters the
output short circuit protection wait state while V
SCP
remains low.
Soft-Start Time
t
s
(
sec
)
~
0
.
84
×
C
SCP
(
µ
F
)
2. Short Circuit Protection
In response to a sudden drop of the switching regulator output, the device locks the error amplifier, OE
pin, at V
OS
+
, and starts feeding currents into the capacitor at SCP pin to achieve in a voltage value of
approximately 0.84V at this pin. This chain reaction protects the circuit by keeping the SCP pin and
output pin low. Users could reverse this process by restarting the device.
Short Circuit Detection Time
t
SCP
(
sec
)
~
0
.
84
×
C
SCP
(
µ
F
)
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