AAT1146IJS-0.6-T1 Analogic Tech, AAT1146IJS-0.6-T1 Datasheet - Page 14

• Manufacturer Part Number: AAT1146IJS-0.6-T1
• Description: Switching Converters, Regulators & Controllers Fast Transient 400mA DC/DC Converter
• Manufacturer: Analogic Tech

Specifications of AAT1146IJS-0.6-T1

• Output Voltage: 0.6 V (Adj.)
• Output Current: 400 mA (Max)
• Input Voltage: 2.7 V
• Switching Frequency: 1 MHz
• Operating Temperature Range: - 40 C to + 85 C
• Mounting Style: SMD/SMT
• Package / Case: SC70JW-8
• Lead Free Status / Rohs Status: Lead free / RoHS Compliant

Thermal Calculations
There are three types of losses associated with the
AAT1146 step-down converter: switching losses, con-
duction losses, and quiescent current losses. Conduction
losses are associated with the R
the power output switching devices. Switching losses are
dominated by the gate charge of the power output
14
SwitchReg
Table 2: Adjustable Resistor Values For Use With
V
OUT
1.85
0.8
0.9
1.0
1.1
1.2
1.3
1.4
1.5
1.8
2.0
2.5
3.3
(V)
0.6V Step-Down Converter.
TM
R2 = 59kΩ
R1 (kΩ)
Figure 5: AAT1146 Adjustable Version Evaluation Board Schematic
19.6
29.4
39.2
49.9
59.0
68.1
78.7
88.7
118
124
137
187
267
(for Fixed Version, R1 is a short and C4, R2 are open).
DS(ON)
V
OUT
R2 = 221kΩ
characteristics of
GND
GND2
10μF
C1
=1.8V
1.00M
113K
150K
187K
221K
261K
301K
332K
442K
464K
523K
715K
75K
R1
V
IN
w w w . a n a l o g i c t e c h . c o m
C3
n/a
C4
100pF
L1
4.7μH
Enable
118k
R1
1
2
3
R2
59k
LX
Fast Transient 400mA Step-Down Converter
C2 4.7μF 10V 0805 X5R
C1 10μF 6.3V 0805 X5R
U1 AAT1146 SC70JW-8
L1 CDRH3D16-4R7
switching devices. At full load, assuming continuous con-
duction mode (CCM), a simplified form of the losses is
given by:
I
term t
verter switching losses.
For the condition where the step-down converter is in
dropout at 100% duty cycle, the total device dissipation
reduces to:
Since R
vary with input voltage, the total losses should be inves-
tigated over the complete input voltage range.
Given the total losses, the maximum junction tempera-
ture can be derived from the θ
age which is 160°C/W.
Q
is the step-down converter quiescent current. The
C2
4.7μF
1
2
3
4
P
TOTAL
sw
EN
OUT
VIN
LX
U1
AAT1146
DS(ON)
is used to estimate the full load step-down con-
+ (t
=
PGND
PGND
PGND
AGND
, quiescent current, and switching losses all
I
O
P
sw
2
TOTAL
T
· (R
· F · I
8
7
6
5
J(MAX)
DSON(HS)
= I
O
PRODUCT DATASHEET
= P
O
+ I
2
· R
TOTAL
Q
) · V
· V
DSON(HS)
O
· Θ
IN
JA
+ R
AAT1146
V
for the SC70JW-8 pack-
JA
IN
DSON(LS)
+ I
+ T
Q
AMB
· V
1146.2009.05.1.7
· [V
IN
IN
- V
O
])