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Электронный компонент: AAT1109-S-T

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Advanced Analog Technology, Inc.
Advanced Analog Technology, Inc
.
Page 1 of 18 V 1.0
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
PIN CONFIGURATION
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
A
10
. With the minimal external components,
the AAT1109 offers a simple and economical
solution.



Advanced Analog Technology, Inc.
Advanced Analog Technology, Inc
.
Page 2 of 18 V 1.0
AAT1109
PIN DESCRIPTION
PIN NO. NAME I/O
DESCRIPTION
1 CE
I
Chip Enable Input PinInternal Pull "H"
2
SCP
I Soft-Start and SCP Capacitor Connection Pin
3
DD
V
- Power
Supply
4
OUT
O Totem Pole Type Output Pin
5 GND
-
Ground
6
OSC
O Capacitor and Resistor Connection Pin for Setting the Oscillation Frequency
7
OE
O Output Pin of Error Amplifier
8
IE
I Inverting Input Pin of Error Amplifier
ABSOLUTE MAXIMUM RATINGS
CHARACTERISTICS SYMBOL
VALUE
UNIT
Supply Voltage
DD
V
7 V
Output Current
O
I
120
/
120
+
-
mA
Operating Free-Air Temperature Range
C
T
20
-
to
85
+
C
o
Storage Temperature Range
storage
T
45
-
to
125
+
C
o
Power Dissipation
d
P
500
mW
RECOMMENDED OPERATING CONDITIONS
SYMBOL
MIN
MAX
UNIT
Supply Voltage
DD
V
2.6 6.5 V
Error Amplifier Input Voltage
I
V
0.5 1.6 V
Oscillator (OSC) Capacitance
OSC
C
100 10,000
pF
Oscillator (OSC) Resistance
OSC
R
1.0 10.0
k
Oscillator (OSC) Frequency
OSC
f
10 1,000 kHz
Output Current
O
I
30
/
30
-
+
mA
Operating Free-Air Temperature
C
T
20
-
85
+
C
o
Advanced Analog Technology, Inc.
Advanced Analog Technology, Inc
.
Page 3 of 18 V 1.0
AAT1109
ELECTRICAL CHARACTERISTICS,
DD
V
= 3.3V (UNLESS OTHERWISE
SPECIFIED) (SEE NOTE 1)
OSCILLATOR
PARAMETER
SYMBOL
TEST CONDITION
MIN TYP MAX UNIT
Oscillation Frequency
OSC
f
OSC
C
=270pF
k
2
.
4
R
OSC
=
400
500 600 kHz
Frequency Variation with
Temperature
T
f
C
20
T
o
C
-
=
to
C
85
o
+
5
%
Frequency Input Stability
V
f
6.5V
to
2.6V
V
DD
=
1
%
UNDER-VOLTAGE PROTECTION
PARAMETER
TEST CONDITION
MIN TYP MAX UNIT
Upper Threshold Voltage
UPH
V
C
25
T
C
o
=
2.12 2.47 2.85
V
Lower Threshold Voltage
UPL
V
C
25
T
C
o
=
1.96 2.28 2.63
V
Hysteresis
(
)
UPL
UPH
V
V
-
HYS
V
C
25
T
C
o
=
0.19
V
Note 1: Typical values of all parameters are specified at
C
25
T
C
o
=
.
SHORT CIRCUIT PROTECTION CONTROL
PARAMETER
TEST
CONDITION
MIN TYP
MAX UNIT
Input Threshold Voltage
1
r
V
1.160 1.262
1.360
V
Short-Circuit Detection
Threshold Voltage
2
r
V
1.160 1.262
1.360
V
Charging Current
SCP
I
V
0
V
SCP
=
15
.
2
-
50
.
1
-
00
.
1
-
A
SOFT-START
PARAMETER
TEST
CONDITION
MIN TYP
MAX UNIT
Charging Current
CS
I V
0
V
SCP
=
15
.
2
-
50
.
1
-
00
.
1
-
A
Voltage at Soft-Start
Completion
ts
V
1.160 1.262
1.360
V
SHUTDOWN CONTROL
PARAMETER
TEST
CONDITION
MIN TYP
MAX UNIT
Shutdown Enable Voltage
SE
V
0.5
V
Shutdown Release Voltage
SR
V
2.0
V
Advanced Analog Technology, Inc.
Advanced Analog Technology, Inc
.
Page 4 of 18 V 1.0
AAT1109
ELECTRICAL CHARACTERISTICS,
DD
V
= 3.3V (UNLESS OTHERWISE
SPECIFIED (SEE NOTE 1)
IDLE PERIOD ADJUSTMENT SECTION
PARAMETER
TEST
CONTION
MIN TYP
MAX
UNIT
Maximum Duty Cycle
Duty
t
pF
270
C
OSC
=
,
=
k
2
.
4
R
OSC
,
V
12
.
1
V
OE
=
75 85 93 %
EA (ERROR AMPLIFIER)
PARAMETER
TEST CONDITION
MIN
TYP MAX UNIT
Input Threshold Voltage
T
V
V
7
.
0
V
OE
=
1.249 1.262 1.275 V
T
V
Input Stability
V
T
V
V
5
.
6
to
6
.
2
V
DD
=
2 8
mV
T
V
Variation with
Temperature
T
T
V
C
85
C to
20
T
C
o
o
+
-
=
1 %
Input Bias Current
B
I
0.1
1.0
A
+
OS
V
1.4
1.7
Output Voltage Swing
-
OS
V
0.05
0.20
V
Output Sink Current
+
OS
I
V
7
.
0
V
OE
=
3 20
mA
Output Source Current
-
OS
I
V
7
.
0
V
OE
=
45
-
75
-
A
Open-Loop Voltage Gain
VO
A
70 85 dB
OUTPUT SECTION
PARAMETER
TEST CONDITION
TYP MAX UNIT
High-Level Output Voltage
OH
V
mA
30
I
o
-
=
1.9 2.3 V
Low-Level Output Voltage
OL
V mA
30
I
o
+
=
0.8
1.2
V
Rise Time
RISE
t
pF
000
,
1
C
L
=
100 ns
Fall Time
FALL
t
pF
000
,
1
C
L
=
100 ns
OPERATING CURRENT
PARAMETER
TEST CONDITION
MIN
TYP MAX UNIT
OFF
DD
I
-
Output "OFF" State
1.3
mA

Supply Current
ON
DD
I
-
=
k
2
.
4
R
OSC
1.6
mA
Advanced Analog Technology, Inc.
Advanced Analog Technology, Inc
.
Page 5 of 18 V 1.0
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
(
SCP
V
) is input to the PWM comparator, so that the ON duty of the OUT pin is determined by the
SCP
V
.
When the soft-started mode is completed, its setting voltage remains high and the circuit enters the
output short circuit protection wait state while
SCP
V
remains low.
Soft-Start Time
( )
( )
F
C
84
0
t
SCP
s
.
~
sec

2. Short Circuit Protection
In response to a sudden drop of the switching regulator output, the device locks the error amplifier, OE
pin, at
+
OS
V
, 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
( )
( )
F
C
84
0
t
SCP
SCP
.
~
sec