AAT1146IJS-0.6-T1 Analogic Tech, AAT1146IJS-0.6-T1 Datasheet - Page 10

• 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

Control Loop
The AAT1146 is a peak current mode step-down con-
verter. The current through the P-channel MOSFET (high
side) is sensed for current loop control, as well as short
circuit and overload protection. A fixed slope compensa-
tion signal is added to the sensed current to maintain
stability for duty cycles greater than 50%. The peak cur-
rent mode loop appears as a voltage-programmed cur-
rent source in parallel with the output capacitor.
The output of the voltage error amplifier programs the
current mode loop for the necessary peak switch current
to force a constant output voltage for all load and line
conditions. Internal loop compensation terminates the
transconductance voltage error amplifier output. For
fixed voltage versions, the error amplifier reference volt-
age is internally set to program the converter output
voltage. For the adjustable output, the error amplifier
reference is fixed at 0.6V.
Soft Start / Enable
Soft start limits the current surge seen at the input and
eliminates output voltage overshoot. When pulled low,
the enable input forces the AAT1146 into a low-power,
non-switching state. The total input current during shut-
down is less than 1μA.
10
SwitchReg
TM
Figure 1: Enhanced Transient Response Schematic.
V
10µF
GND
GND2
OUT
C1
V
IN
w w w . a n a l o g i c t e c h . c o m
R1
L1
4.7µH
Enable
118k
C
FF
1
2
3
59k
R2
LX
C1 10µF 10V 0805 X5R
C2 4.7µF 10V 0805 X5R
U1 AAT1146 SC70JW-8
L1 CDRH3D16-4R7
Fast Transient 400mA Step-Down Converter
Current Limit and
Over-Temperature Protection
For overload conditions, the peak input current is limit-
ed. To minimize power dissipation and stresses under
current limit and short-circuit conditions, switching is
terminated after entering current limit for a series of
pulses. Switching is terminated for seven consecutive
clock cycles after a current limit has been sensed for a
series of four consecutive clock cycles.
Thermal protection completely disables switching when
internal dissipation becomes excessive. The junction
over-temperature threshold is 140°C with 15°C of hys-
teresis. Once an over-temperature or over-current fault
conditions is removed, the output voltage automatically
recovers.
Under-Voltage Lockout
Internal bias of all circuits is controlled via the V
Under-voltage lockout (UVLO) guarantees sufficient V
bias and proper operation of all internal circuitry prior to
activation.
4.7µF
C2
1
2
3
4
U1
AAT1146
EN
OUT
VIN
LX
PGND
PGND
PGND
AGND
8
7
6
5
PRODUCT DATASHEET
AAT1146
1146.2009.05.1.7
IN
input.
IN