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Advanced Analog Technology, Inc.
AAT1109A
Preliminary and Provisional
ONE-CHANNEL BOOST SWITCHING REGULATOR
Features
Under-voltage lockout protection Totem pole output Output short circuit protection Incorporates soft start function Wide operating frequencyG 10kHz to 1MHz Shut down control Low dissipation current : Typical 1.6mA in operation Sop-8 & Tssop-8 package available
General Description
The AAT1109A is a one-channel switching regulator control IC incorporating a soft start function and a short circuit protection function. Each device consists of an on-chip voltage reference, error amplifier, pulse width modulation controller, under-voltage protection, soft start and short circuit protection circuits. Switching frequencies up to 1MHz are set by an external resistor and capacitor. Soft-start time can be implemented by the SCP capacitor. Additionally, a chip enable feature is provided to power down reducing the supply current to 10uA. With a minimum number of external components, the AAT1109A offers a simple and cost effective solution.
Pin Configuration
TOP VIEW -IN SCP Vcc CE 1 2 3 4 8 7 6 5 FB OSC GND OUT
(SOP-8 PACKAGE) (TSSOP-8 PACKAGE)
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Advanced Analog Technology, Inc.
AAT1109A
Pin Description
Pin # 1 2 3 4 5 6 7 8 Name -IN SCP Vcc CE OUT GND OSC FB I/O Description I Error amplifier inverting input pin I Soft start and SCP capacitor connection pin Power supply I Chip enable input pin] internal pull "H"^ O Totem-type output pin Ground O Capacitor and resistor connection pin for setting the oscillation frequency O Error amplifier output pin
Absolute Maximum Ratings
CHARACTERISTICS Supply voltage SYMBOL VDD VALUE 7 UNIT V
Output current Operating free-air temperature range Storage temperature range Power dissipation
IO
Tope Tstg
-120/+120 -20 to 85 -65 to 150 500
mA
o o
C C
Pd
mW
Recommended Operating Conditions
Supply voltage, VDD Error amplifier input voltage OSC capacitor OSC resistor Oscillator frequency Output current Operating free-air temperature
Symbol VDD VI CT RT f OSC Min 2.6 0.5 100 1.0 Max 6.5 1.6 10000 10 Unit V V pF k[
10 -20
1000 +30/-30 85
kHz mA
o
IO
Tope
C
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AAT1109A
Electrical Characteristics, VDD = 3.3V (Unless Otherwise Specified) (See Note 1) Oscillator
Parameter Test Condition
Min
Typ
Oscillation frequency Frequency variation with temperature Frequency input stability
f OSC
C T = 270pF, R T = 4.2k[
400
500 5
Max Unit 600 KHz
f dT
f dV VDD = 2.6V to 6.5V
% %
1
Under-voltage Protection
Parameter Test Condition Min Typ Max Unit
Upper threshold voltage Lower threshold voltage Hysteresis ( VUPH - VUPL )
VUPH VUPL VHYS
TA = 25 C TA = 25 oC TA = 25 C TA =25 C.
o
o
2.12 2.47 1.96 2.28 0.3
2.85 2.63
V V V
o
Note1 : Typical values of all parameters are specified at
Short Circuit Protection Control
Parameter Test Condition Min Typ Max Unit
Input threshold voltage Short-circuit detect threshold voltage Charging current
Vr1
1.16 1.262 1.16 1.262 Vscp=0v -1.0 -1.5
1.36 1.36 -2.15
V V A
Vr 2
I SCP
Soft start
Parameter Test Condition Min Typ Max Unit
Charging current Voltage at soft start completion
Ics Vts
Vscp=0v
-1.0
-1.5
-2.15 1.36
A V
1.16 1.262
Shun Down Control
Parameter Test Condition Min Typ Max Unit
Shut down release voltage Shut down enable voltage
Vsdh Vsdl 2.0
0.5
V V
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Advanced Analog Technology, Inc.
AAT1109A
Electrical Characteristics, VDD = 3.3V (Unless Otherwise Specified) (See Note 1) Idle period adjustment section
Parameter Test Conditions Min Typ Max Unit
Maximum duty cycle
tDUTY
C T = 270pF, R T = 4.2k[ VFB = 1.12v
75
85
93
%
EA (Error Amplifier)
Parameter Test Condition
Input threshold voltage VT input stability VT variation with temperature Input bias current Output voltage swing Output sink current Output source current Open-loop voltage amplification
VT VTdV VTdT
VFB =
0.7v Vdd = 2.6 to 6.5v TA = -20 oC to 90 oC
Min Typ Max Unit 1.249 1.262 1.275 V 2 8 mV 1 %
IB
VOM + VOM - I OM + I OM - A VD FB=0.7V FB=0.7V 3 -45 70 1.4
0.1 1.7 0.05 20 -75 85
1 0.2
A V mA A dB
Output section
Parameter Test Condition
Typ
Max Unit
High-level output voltage Low-level output voltage Rise time Fall time
VOH VOL Trise Tfall
IO=-30mA IO=+30mA CL=1000pF CL=1000pF
1.9
2.3 0.8 100 100
1.2
V V nS nS
Operating Current
Parameter Test Condition
Min
Supply current
I DD-OFF I DD-ON
Output "OFF"state RT =4.2k
Typ 1.3
Max Unit mA
1.6
mA
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AAT1109A
How to set the time constant for soft start and short circuit protection 1.Soft start
At power on, the AAT1109A operates in soft start mode. The capacitor Cscp connected to SCP pin starts charging at a constant current. In the soft start mode, the voltage at SCP pin (VSCP) is input to the PWM comparator, so that the ON duty of the OUT pin is controlled by the VSCP. On completion of soft start operation, the voltage at the SCP pin stays low, the input from soft start circuit to the PWM comparator stay high, and enter the short circuit protection waiting state. Soft start time Ts(sec) ~ 0.84 N C SCP (uF) 2.Short circuit protection If the switching regulator output suddenly drops due to loading effect , the error amplifier output is fixed at VOM+ and capacitor CSCP starts charging. When the voltage at the SCP pin reaches approximately 1.26V ,the output pin set low and SCP pin stays low. Once the protection circuit operates, the circuit can be recovered by setting the power supply. Short circuit detection time Tscp(sec) ~ 0.84 N C SCP (uF)
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Advanced Analog Technology, Inc.
AAT1109A
Function Block Diagram
VDD
CE
C h ip E n a b le
IR E F
GND
V ref 1 .2 6 V SCP com p.
LATCH
SCP
S o ft sta rt SCP
UVC UVC
CE O SC O SC
CE UVLO
VCC CE
V re f 1 .2 6 v
PW M C om p.
FB
VREF CE
VCC D TC 0 .7 6 5 V E rr-A m p V ref 1 .2 6 V
OUT
UVC
-IN CE
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AAT1109A
Application Circuit 1 BOOST(step-up)
VDD
L1 D1
CE
CE SCP
4
1
-IN
C4 R4
VOUT
2
8
FB OSC
R3 C3
VDD C1 R1 -IN R2 Q1 C2
VDD 3
7
OUT
5
6
GND
AAT1109A
Application Circuit 2 (with charge pump)
VDD
L1 D1 VOUT C2 R1 -IN R2 Q1
CE
CE
4
1
-IN
C4 R4
SCP
VDD
2
8
FB
C1
VDD 3
7
OSC
R3 C3
OUT
5
6
GND
V
P
tuoV*3
D2
5C D6 D3 7C 4D C8 9 C C10
AAT1109A
C6
D5
D7
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AAT1109A
Boost ] Step-up^ Timing Chart
FB Reference input for short circuit ldle period setting voltage Soft start setting voltage OSC
1.262V
OUTPU T
SCP soft start
output short circuit
output short circuit
Ts
2.47V Lockout free
VDD
Tscp
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AAT1109A
Package Dimension (Unit: Mil)
8-pin SOP
DIMENSIONS IN MILLIMETERS SYMBOLS A A1 A2 b C D E E1 e L y MIN 1.47 0.10 --0.33 0.19 4.80 5.80 3.80 --0.38 --0 NOM. 1.60 --1.45 0.41 0.20 4.85 6.00 3.90 1.27 0.71 ----MAX 1.73 0.22 --0.51 0.25 4.95 6.20 4.00 --1.27 0.076 0
DEMINSIONS IN INCHES MIN 0.058 0.004 --0.013 0.0075 0.189 0.228 0.150 --0.015 --0 NOM. 0.063 --0.057 0.016 0.008 0.191 0.236 0.154 0.050 0.028 ----MAX 0.068 0.008 --0.020 0.0098 0.195 0.244 0.157 --0.050 0.00. 0
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Advanced Analog Technology, Inc.
AAT1109A
Package Dimension (Unit: Mil)
8-pin TSSOP
D
E1
E
L C
Dimension
Millimeters Min Nom
1.10 0.10 0.22 0.127 3.00 6.40 4.40 0.65 0.60 3X
Inches Max
1.20 0.175 -----------3.10 6.60 4.50 --0.75 8X
A
Min
0.039 0.002 ------------0.114 0.244 0.169 --0.020 0X
Nom
0.043 0.004 0.008 0.005 0.118 0.252 0.173 0.026 0.024 3X
Max
0.047 0.006 ------------0.122 0.260 0.177 --0.028 8X
A A1
1.00 0.025 ----------2.90 6.20 4.30 --0.45 0X
A1
b C D E E1 e L
b
e
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