AAT1230ITP-T1 Analogic Tech, AAT1230ITP-T1 Datasheet - Page 11

• Manufacturer Part Number: AAT1230ITP-T1
• Description: Switching Converters, Regulators & Controllers 18V 100mA Step-Up Converter
• Manufacturer: Analogic Tech

Specifications of AAT1230ITP-T1

• Lead Free Status / Rohs Status: Lead free / RoHS Compliant

The average diode current is equal to the output
current.
The average output current multiplied by the for-
ward diode voltage determines the loss of the out-
put diode.
Diode junction temperature can be estimated.
Output diode junction temperature should be
maintained below 110ºC, but may vary depending
on application and/or system guidelines.
diode θ
area on the cathode. PCB heatsinking the anode
may degrade EMI performance.
The reverse leakage current of the rectifier must be
considered to maintain low quiescent (input) cur-
rent and high efficiency under light load. The recti-
fier reverse current increases dramatically at high
temperatures.
1230.2007.06.1.6
10000
1000
100
10
0.00
JA
T
can be minimized with additional PCB
J(DIODE)
0.10
P
LOSS(DIODE)
= T
0.20
Forward Voltage (V)
I
AVG(TOT)
B340LA
AMB
0.30
= I
= I
+ Θ
= I
OUT
AVG(TOT)
MBR0530
JA
OUT
0.40
· V
· P
F
LOSS(DIODE)
· V
0.50
ZHCS350
F
BAT42W
0.60
The
0.70
Selecting the Boost Inductor
The AAT1230/1230-1 controller utilizes hysteretic
control and the switching frequency varies with out-
put load and input voltage. The value of the induc-
tor determines the maximum switching frequency
of the AAT1230/1230-1 boost converter. Increased
output inductance decreases the switching fre-
quency, resulting in higher peak currents and
increased output voltage ripple. To maintain 2MHz
maximum switching frequency and stable opera-
tion, an output inductor sized from 1.5µH to 2.7µH
is recommended.
A better estimate of D
known.
Where V
not known, it can be estimated at 0.5V.
Manufacturer’s specifications list both the inductor
DC current rating, which is a thermal limitation, and
peak inductor current rating, which is determined
by the saturation characteristics. Measurements at
full load and high ambient temperature should be
completed to ensure that the inductor does not sat-
urate or exhibit excessive temperature rise.
The output inductor (L) is selected to avoid satura-
tion at minimum input voltage, maximum output load
conditions. Peak current may be estimated using
the following equation, assuming continuous con-
duction mode. Worst-case peak current occurs at
minimum input voltage (maximum duty cycle) and
maximum load. Switching frequency can be estimat-
ed from the curves and assumes a 2.2µH inductor.
18V 100mA Step-Up Converter
2.0
1.8
1.6
1.4
1.2
1.0
0.8
0.6
0.4
40
V
F
V
OUT
IN
V
V
is the Schottky diode forward voltage. If
OUT
IN
= 2.7V
D
= 18V
= 3.0V
= 18V
MAX
50
V
=
V
OUT
IN
V
(V
V
= 2.7V
OUT
AAT1230/1230-1
Output Current (mA)
IN
= 15V
60
= 3.0V
OUT
= 15V
MAX
(V
+ V
OUT
70
is possible when V
V
V
F
OUT
IN
+ V
- V
= 3.6V
= 18V
F
IN(MIN)
)
80
V
V
OUT
)
IN
= 3.6V
= 15V
90
100
F
11
is