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AAT1157 PDF 데이터시트 : 부품 기능 및 핀배열

부품번호 AAT1157
기능 DC/DC Converter
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AAT1157 데이터시트, 핀배열, 회로
General Description
The AAT1157 SwitchReg™ is a member of
AnalogicTech's Total Power Management IC™
(TPMIC™) product family. The step-down switch-
ing converter is ideal for applications where fixed
frequency and low ripple are required over the full
range of load conditions. The 2.7V to 5.5V input
voltage range makes the AAT1157 ideal for single-
cell lithium-ion/polymer battery applications.
Capable of up to 1.2A with internal MOSFETs, the
current-mode controlled IC provides high efficiency
over a wide operating range. Fully integrated com-
pensation simplifies system design and lowers
external parts count. The device operates at a
fixed 1MHz switching frequency across all load
conditions.
The AAT1157 is available in the Pb-free, 16-pin
3x3mm QFN package and is rated over the -40°C
to +85°C temperature range.
AAT1157
1MHz 1.2A Buck DC/DC Converter
Features
SwitchReg
• VIN Range: 2.7V to 5.5V
• Up to 95% Efficiency
• 110 mRDS(ON) Internal Switches
• <1µA Shutdown Current
• 1MHz Buck Switching Frequency
• Fixed or Adjustable VOUT 0.8V
• Integrated Power Switches
• Current Mode Operation
• Internal Compensation
• Stable with Ceramic Capacitors
• Constant PWM Operation for Low Output
Ripple
• Internal Soft Start
• Over-Temperature Protection
• Current Limit Protection
• 16-Pin QFN 3x3mm Package
• -40°C to +85°C Temperature Range
Applications
www.DataSheet4U.com
• HDD MP3 Players
• Notebook Computers
• PDAs
• Point-of-Load Regulation
• Set Top Boxes
• Smart Phones
• Wireless Notebook Adapters
Typical Application
3.3V
C1
10µF
R1
100
C2
0.1µF
U1
AAT1157
12 VP
FB 4
11 VP
LX 15
10 VP
LX 14
7 EN
LX 13
9 VCC
N/C 16
6 N/C PGND 3
8 N/C PGND 2
5 SGND PGND 1
L1
3.0µH
2.5V
R3
187k
R4 C3-C4
59k 2x 22µF
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AAT1157 pdf, 반도체, 판매, 대치품
AAT1157
1MHz 1.2A Buck DC/DC Converter
Electrical Characteristics1
VIN = VCC = VP = 5V, TA = -40°C to +85°C, unless otherwise noted. Typical values are at TA = 25°C.
Symbol
Description
Conditions
VIN
VOUT
VOUT/VOUT
VOUT(VOUT*VIN)
IQ
ISHDN
ILIM
VUVLO
VUVLO(HYS)
VIL
VIH
IIL
IIH
RDS(ON)H
RDS(ON)L
FOSC
TSD
Input Voltage Range
Output Voltage Tolerance
Load Regulation
Line Regulation
Quiescent Supply Current
Shutdown Current
Current Limit
Under-Voltage Lockout
Under-Voltage Lockout Hysteresis
Input Low Voltage
Input High Voltage
Input Low Current
Input High Current
High Side Switch On Resistance
Low Side Switch On Resistance
Oscillator Frequency
Over-Temperature Shutdown
Threshold
VIN = VOUT + 0.2 to 5.5V,
IOUT = 0 to 1.2A
VIN = 4.2V, ILOAD = 0 to 1.2A
VIN =2.7 to 5.5V
No Load
VEN = 0V, VIN = 5.5V
TA = 25°C
VIN Rising, VEN = VCC
VIN Falling, VEN = VCC
VIN = VFB = 5.5V
VIN = VFB = 0V
TA = 25°C
TA = 25°C
TA = 25°C
THYS
Over-Temperature Shutdown
Hysteresis
Min Typ Max Units
2.7 5.5 V
-4 +4 %
±2.5 %
±0.1 %/V
160 300 µA
1.0 µA
1.7 A
2.5 V
1.2
250 mV
0.6 V
1.4 V
1.0 µA
1.0 µA
110 150 m
100 150 m
750 1000 1250 kHz
140 °C
15 °C
1. The AAT1157 is guaranteed to meet performance specifications over the -40°C to +85°C operating temperature range and is assured
by design, characterization, and correlation with statistical process controls.
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AAT1157 전자부품, 판매, 대치품
Functional Block Diagram
AAT1157
1MHz 1.2A Buck DC/DC Converter
VCC VP = 2.7V to 5.5V
1.0V REF
FB
OP. AMP
CMP
DH
LOGIC
1M
OSC
Temp.
Sensing
DL
LX
SGND
EN
PGND
Applications Information
Control Loop
The AAT1157 is a peak current mode buck converter.
The inner wide bandwidth loop controls the inductor
peak current. The inductor current is sensed through
the P-channel MOSFET (high side) and is also used
for short-circuit and overload protection. A fixed slope
compensation signal is added to the sensed current
to maintain stability for duty cycles greater than 50%.
The loop appears as a voltage-programmed current
source in parallel with the output capacitor.
The voltage error amplifier output programs the
current loop for the necessary inductor current to
force a constant output voltage for all load and line
conditions. The external voltage feedback resistive
divider divides the output voltage to the error ampli-
fier reference voltage of 0.6V. The low-DC gain
voltage error amplifier eliminates the need for
external compensation components while provid-
ing sufficient DC loop gain for good load regulation.
The voltage loop crossover frequency and phase
margin are set by the output capacitor.
Soft Start/Enable
Soft start increases the inductor current limit point
in discrete steps once the input voltage or enable
input is applied. It limits the current surge seen at
the input and eliminates output voltage overshoot.
When pulled low, the enable input forces the
AAT1157 into a non-switching shutdown state.
The total input current during shutdown is less
than 1µA.
Power and Signal Source
Separate small signal ground and power supply
pins isolate the internal control circuitry from the
noise associated with the output power MOSFET
switching. The low-pass filter R1 and C2 shown in
the Figure 1 schematic filters the input noise asso-
ciated with the power switching.
Current Limit and Over-Temperature
Protection
For overload conditions, the peak input current
sensed through the high-side P-channel MOSFET
is limited. Thermal protection completely disables
switching when internal dissipation becomes
excessive, protecting the device from damage. The
junction over-temperature threshold is 140°C with
15°C of hysteresis. Once the over-temperature or
over-current fault is removed, the AAT1157 auto-
matically recovers.
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