AAT1160 AAT, AAT1160 Datasheet - Page 10

• Manufacturer Part Number: AAT1160
• Description: Step Up Current Mode PWM Converter
• Manufacturer: AAT

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Operation Information:
Setting the Output Voltage:
Output voltage is set by using a feedback pin and a
resistor divider; equation is as follows:
Soft-Start:
The soft-start function is embedded with a typical
setting of 14ms
Operation Frequency Setting:
Pin4 (FREQ) can set PWM operation to low with
Diode Selection:
Schottky diode for the boost regulator must be
selected correctly depending on the output voltage
and the output current. The diode must have a
reverse voltage equal to or greater than the output
voltage. In addition, the diode current must
exceed the switch current limit as a lower forward
voltage will increase efficiency.
Inductor Selection:
D: PWM duty
Maximum current of the inductor must be greater
than
V =1.265 (1+R1/R2)
f
f
I
V /
OSC
OSC
L(peak)
O
P1
V =1/ (1-D)
=600kHz, or set PWM operation to high with
=1.2 MHz.
I
IN
L(peak)
=
I +
IN
V *D/(2*L*
IN
Advanced Analog Technology, Inc.
–
–
f )
S
Advanced Analog Technology, Inc
台灣類比科技股份有限公司
Page 10 of 14
The Compensation:
Pin17 (EO) series with
compensation, usually range as 1k Ω ≤
Ω , 100pF ≤
only for reference purpose, as PCB has a lot of
noise or parasitic capacitance and resistance, it
often requires on board adjustment.
The key steps for step-up compensation are as
follows:
Transconductance (from FB to CC),
Current-sense amplifier transresistance,
(0.275V/A)
For continuous conduction, the right-half-plane
zero frequency (
duty cycle=1-(
and
target, crossover (
For example, if oscillation frequency is assumed to
be
L=4.7µH, then:
If
1.25/5)(10/0.275)*[105µS/(6.28*14kHz)](1/4)=2.7
nF
Now selected
requirements. For example, if 4% of transient
droop is allowed, input to error amplifier moves
f
I
f
C =(
RHPZ
OUT
RHPZ
C
f =14kHz, C
f
C
OSC
I
=
=5(2.5/5)
V /
=0.5A, then
LOAD
V (1-D)
FB
O
=500kHz,
V )(
is the maximum output current. Typical
C ≤ 6,800pF. Standard formulas are
O
C
V /
2
R has fulfilled transient-droop
/(2 π *4.7*10
R
f
IN
C
C
2
RHPZ
/(2 π *L*
f ), is 1/6 of the RHPZ.
would be calculated as:
LOAD
C
V ), L is the inductance value,
R
V =2.5V,
O
LOAD
) is given by the following:
–
/
IN
.
R )(
–
R
CS
C
=10 Ω . If we select
I
LOAD
&
-6
g /2π*
*0.5)=84.65kHz
m
C
) where D=the
V =5V, and
C
AAT1160
O
for
g
f )(1-D)/2=(
V 1.0
R ≤ 200k
m
C
C
R
(105µS)
CS