GRM31CR60J106KA01L [ANALOGICTECH]
1MHz 1.2A Buck DC/DC Converter; 1MHz的1.2A降压型DC / DC转换器
| 型号： | GRM31CR60J106KA01L |
| 厂家： | 
ADVANCED ANALOGIC TECHNOLOGIES |
| 描述： | 1MHz 1.2A Buck DC/DC Converter |
| 文件： | 总14页 (文件大小：395K) |
| 中文： | 中文翻译 | 下载： | 下载PDF数据表文档文件 |
AAT1157
1MHz 1.2A Buck DC/DC Converter
™
SwitchReg
General Description
Features
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.
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•
•
•
•
•
•
•
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VIN Range: 2.7V to 5.5V
Up to 95% Efficiency
110 mΩ RDS(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
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16-Pin QFN 3x3mm Package
-40°C to +85°C Temperature Range
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.
Applications
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HDD MP3 Players
Notebook Computers
PDAs
Point-of-Load Regulation
Set Top Boxes
Smart Phones
Wireless Notebook Adapters
Typical Application
U1
AAT1157
3.3V
2.5V
4
12
VP
FB
LX
R3
187k
15
14
13
16
3
11
R1
100
VP
10
L1
3.0µH
VP
LX
C1
10µF
7
EN
LX
9
VCC
N/C
N/C
N/C
R4
59k
C3-C4
2x 22µF
6
PGND
PGND
2
8
C2
0.1µF
1
5
SGND PGND
1157.2005.11.1.4
1
AAT1157
1MHz 1.2A Buck DC/DC Converter
Pin Descriptions
Pin #
Symbol
Function
1, 2, 3
PGND
Main power ground return pin. Connect to the output and input capacitor
return. (See board layout rules.)
4
FB
Feedback input pin. This pin is connected to the converter output. It is used to
set the output of the converter to regulate to the desired value via an internal
resistive divider. For an adjustable output, an external resistive divider is con-
nected to this pin.
5
7
SGND
EN
Signal ground. Connect the return of all small signal components to this pin.
(See board layout rules.)
Enable input pin. A logic high enables the converter; a logic low forces the
AAT1157 into shutdown mode reducing the supply current to less than 1µA.
The pin should not be left floating.
6, 8, 16
9
N/C
Not internally connected.
VCC
Bias supply. Supplies power for the internal circuitry. Connect to input power
via low pass filter with decoupling to SGND.
10, 11, 12
13, 14, 15
EP
VP
LX
Input supply voltage for the converter power stage. Must be closely decoupled
to PGND.
Connect inductor to these pins. Switching node internally connected to the
drain of both high- and low-side MOSFETs.
Exposed paddle (bottom); connect to PGND directly beneath package.
Pin Configuration
QFN33-16
(Top View)
1
2
3
4
12
11
10
9
PGND
PGND
PGND
FB
VP
VP
VP
VCC
2
1157.2005.11.1.4
AAT1157
1MHz 1.2A Buck DC/DC Converter
Absolute Maximum Ratings1
Symbol
Description
Value
Units
VCC, VP
VLX
VCC, VP to GND
6
V
V
LX to GND
-0.3 to VP + 0.3
-0.3 to VCC + 0.3
-0.3 to -6
VFB
FB to GND
V
VEN
EN to GND
V
TJ
Operating Junction Temperature Range
ESD Rating2 - HBM
-40 to150
°C
V
VESD
3000
Thermal Characteristics
Symbol
Description
Value
Units
θJA
θJC
PD
Maximum Thermal Resistance (QFN33-16)3
Maximum Thermal Resistance (QFN33-16)
Maximum Power Dissipation (QFN33-16) (TA = 25°C)3, 4
50
4.2
2.0
°C/W
°C/W
W
Recommended Operating Conditions
Symbol
Description
Value
Units
T
Ambient Temperature Range
-40 to 85
°C
1. Stresses above those listed in Absolute Maximum Ratings may cause damage to the device. Functional operation at conditions other
than the operating conditions specified is not implied. Only one Absolute Maximum Rating should be applied at any one time.
2. Human body model is 100pF capacitor discharged through a 1.5kΩ resistor into each pin.
3. Mounted on a demo board (FR4, in still air). Exposed pad must be mounted to PCB.
4. Derate 20mW/°C above 25°C.
1157.2005.11.1.4
3
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
Min Typ Max Units
VIN
Input Voltage Range
2.7
5.5
V
V
IN = VOUT + 0.2 to 5.5V,
VOUT
Output Voltage Tolerance
Load Regulation
-4
+4
%
IOUT = 0 to 1.2A
VIN = 4.2V, ILOAD = 0 to 1.2A
VIN =2.7 to 5.5V
No Load
∆VOUT/VOUT
∆VOUT(VOUT*∆VIN) Line Regulation
±2.5
±0.1
160
%
%/V
µA
µA
A
IQ
Quiescent Supply Current
300
1.0
ISHDN
ILIM
Shutdown Current
Current Limit
VEN = 0V, VIN = 5.5V
TA = 25°C
1.7
1.2
VIN Rising, VEN = VCC
2.5
0.6
VUVLO
Under-Voltage Lockout
V
VIN Falling, VEN = VCC
VUVLO(HYS)
VIL
Under-Voltage Lockout Hysteresis
Input Low Voltage
250
mV
V
VIH
Input High Voltage
1.4
V
IIL
Input Low Current
VIN = VFB = 5.5V
VIN = VFB = 0V
TA = 25°C
1.0
1.0
µA
µA
mΩ
mΩ
kHz
IIH
Input High Current
RDS(ON)H
RDS(ON)L
FOSC
High Side Switch On Resistance
Low Side Switch On Resistance
Oscillator Frequency
Over-Temperature Shutdown
Threshold
110
100
150
150
TA = 25°C
TA = 25°C
750
1000 1250
TSD
140
°C
°C
Over-Temperature Shutdown
Hysteresis
THYS
15
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.
4
1157.2005.11.1.4
AAT1157
1MHz 1.2A Buck DC/DC Converter
Typical Characteristics
No Load Supply Current vs. Input Voltage
DC Regulation
(VOUT = 2.5V)
2.0
300
85°C
VIN = 3.6V
1.0
250
200
VIN = 3.0V
VIN = 3.3V
0.0
-1.0
-2.0
-3.0
-4.0
25°C
150
-40°C
100
50
0
1
10
100
1000
10000
2.5
3
3.5
4
4.5
5
5.5
Input Voltage (V)
Output Current (mA)
P-Channel RDSON vs. Input Voltage
N-Channel RDSON vs. Input Voltage
200
200
180
160
140
120
100
80
180
160
140
120
100
80
100°C
25°C
120°C
100°C
120°C
85°C
85°C
25°C
60
60
40
40
20
20
0
0
2.5
3
3.5
4
4.5
5
5.5
2.5
3
3.5
4
4.5
5
5.5
Input Voltage (V)
Input Voltage (V)
Output Voltage vs. Temperature
(VIN = 3.6V; VOUT = 2.5V; IOUT = 1.0A)
Frequency vs. Input Voltage
(VOUT = 1.8V)
0.1
0
1.3
1.28
1.26
1.24
1.22
1.2
-0.1
-0.2
-0.3
-0.4
-0.5
-0.6
-0.7
-40
-20
0
20
40
60
80
100
2.7
3.1
3.5
3.9
4.3
4.7
5.1
5.5
Temperature (°C)
Input Voltage (V)
1157.2005.11.1.4
5
AAT1157
1MHz 1.2A Buck DC/DC Converter
Typical Characteristics
Soft Start
(VOUT = 2.5V; IOUT = 1.2A; VIN = 3.6V)
Output Ripple
(VOUT = 2.5V; IOUT = 1.2A; VIN = 3.6V)
0.02
0.01
0
3
6.0
4.0
3.5
3.0
2.5
2.0
1.5
1.0
0.5
0.0
-0.5
2.5
2
2.0
-0.01
-0.02
-0.03
-0.04
-0.05
-0.06
0.0
1.5
1
-2.0
-4.0
-6.0
-8.0
-10.0
0.5
0
Time (250µs/div)
Time (500ns/div)
Line Transient
(IOUT = 1.2A; VO = 2.5V)
Load Transient Response
(400mA-1.2A; VIN = 3.3V; VOUT = 2.5V)
0.08
0.05
4.0
4.4
4.2
4.0
3.8
3.6
3.4
3.2
3.0
2.8
0.24
3.5
3.0
2.5
2.0
1.5
1.0
0.5
0.0
0.20
0.16
0.12
0.08
0.04
0.00
-0.04
-0.08
0.02
-0.01
-0.04
-0.07
-0.10
-0.13
-0.16
1.2A
400mA
Time (25µs/div)
Time (20µs/div)
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1157.2005.11.1.4
AAT1157
1MHz 1.2A Buck DC/DC Converter
Functional Block Diagram
VCC
VP = 2.7V to 5.5V
1.0V REF
CMP
DH
OP. AMP
FB
LOGIC
LX
DL
1MΩ
OSC
Temp.
Sensing
SGND
EN
PGND
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.
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.
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.
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.
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.
Soft Start/Enable
Soft start increases the inductor current limit point
in discrete steps once the input voltage or enable
1157.2005.11.1.4
7
AAT1157
1MHz 1.2A Buck DC/DC Converter
LX
Enable
U1
AAT1157
VOUT+
VIN+
12
11
10
4
VP
FB
VOUT(V)
R3 (kΩ)
R3
15
14
13
16
3
R1
100
0.8
0.9
1.0
1.1
1.2
1.3
1.4
1.5
1.8
2.0
2.5
3.3
19.6
29.4
39.2
49.9
59.0
68.1
78.7
88.7
118
VP
LX
LX
L1
VP
3.0µH
R2
7
EN
LX
100K
9
6
8
5
C1
10µF
VCC
N/C
N/C
N/C
R4
59.0k
C2
0.1µF
PGND
PGND
137
C3-C4
2x 22µF
2
187
267
1
SGND PGND
GND
GND
C1 Murata 10µF 6.3V X5R GRM42-6X5R106K6.3
C3,C4 MuRata 22µF 6.3V GRM21BR60J226ME39L X5R 0805
L1 Sumida CDRH5D28-3R0NC
Figure 1: AAT1157 Evaluation Board Schematic
Lithium-Ion to 2.5V Converter.
Inductor
Input Capacitor
The output inductor should limit the ripple current to
330mA at the maximum input voltage. This match-
es the inductor current downslope with the fixed
internal slope compensation. For a 2.5V output and
the ripple set to a maximum input voltage of 4.2V,
the inductance value required to limit the ripple cur-
rent to 330mA is 3.0µH. From this calculated value,
a standard value can be selected.
The primary function of the input capacitor is to pro-
vide a low impedance loop for the edges of pulsed
current drawn by the AAT1157. A low ESR/ESL
ceramic capacitor is ideal for this function. To mini-
mize stray inductance, the capacitor should be
placed as closely as possible to the IC. This keeps
the high frequency content of the input current
localized, minimizing radiated and conducted EMI
while facilitating optimum performance of the
AAT1157. Ceramic X5R or X7R capacitors are
ideal for this function. The size required will vary
depending on the load, output voltage, and input
voltage source impedance characteristics. Values
range from 1µF to 10µF. The input capacitor RMS
current varies with the input voltage and the output
voltage. The equation for the RMS current in the
input capacitor is:
Manufacturer's specifications list both the inductor
DC current rating, which is a thermal limitation, and
the peak current rating, which is determined by the
saturation characteristics. The inductor should not
show any appreciable saturation under normal load
conditions. Some inductors may meet the peak and
average current ratings yet result in excessive loss-
es due to a high DCR. Always consider the losses
associated with the DCR and its effect on the total
converter efficiency when selecting an inductor.
VO
VIN
⎛
VO ⎞
VIN ⎠
I
RMS = IO ⋅
⋅ 1 -
⎝
VOUT
∆IPP ⋅ F
⎛
VOUT
⎞
L =
=
⋅ 1 -
⎝
⎠
VIN(MAX)
The input capacitor RMS ripple current reaches a
maximum when VIN is two times the output volt-
age where it is approximately one half of the load
current. Losses associated with the input ceramic
capacitor are typically minimal and are not an
issue. The proper placement of the input capaci-
tor can be seen in the evaluation board layout (C1
in Figure 2).
2.5
V
2.5V
4.2V
⎛
⎞
⎠
⋅ 1 -
0.33A ⋅ 1MHz
⎝
= 3.07µH
For a maximum ripple current of 330mA, the peak
switch and inductor current at 1.2A is 1.365A. A stan-
dard value of 3.0µH can be used in this example. The
3.0µH Sumida series CDRH5D28 inductor has a
24mΩ maximum DCR and a 2.4A DC current rating.
8
1157.2005.11.1.4
AAT1157
1MHz 1.2A Buck DC/DC Converter
3. The trace connecting the FB pin to resistors R3
and R4 should be as short as possible by plac-
ing R3 and R4 immediately next to the
AAT1157. The sense trace connection R3 to
the output voltage should be separate from any
power trace and connect as closely as possible
to the load point. Sensing along a high-current
load trace will degrade DC load regulation.
4. The resistance of the trace from the load return to
the PGND (Pins 1, 2, and 3) and SGND (Pin 5)
should be kept to a minimum. This will help to
minimize any error in DC regulation due to differ-
ences in the potential of the internal signal
ground and the power ground. SGND (Pin 5) can
also be used to remotely sense the output
ground at the point of load to improve regulation.
5. A low pass filter (R1 and C2) provides a clean-
er bias source for the AAT1157 active circuitry.
C2 should be placed as closely as possible to
SGND (Pin 5) and VCC (Pin 9).
Output Capacitor
Since there are no external compensation compo-
nents, the output capacitor has a strong effect on loop
stability. Larger output capacitance reduces the
crossover frequency while increasing the phase mar-
gin. For the 2.5V 1.2A design using the 3.0µH induc-
tor, a 40µF capacitor provides a stable output. Table 1
provides a list of suggested output capacitor values
for various output voltages. In addition to assisting in
stability, the output capacitor limits the output ripple
and provides holdup during large load transitions. The
output capacitor RMS ripple current is given by:
VOUT
⋅
(VIN - VOUT
VIN
)
1
IRMS
=
⋅
L
⋅ F ⋅
2
⋅ 3
For an X7R or X5R ceramic capacitor, the ESR is
very low and the dissipation due to the RMS current
of the capacitor is not a concern. Tantalum capaci-
tors with sufficiently low ESR to meet output voltage
ripple requirements also have an RMS current rating
well beyond that actually seen in this application.
6. For good heat transfer, four 15 mil vias spaced
on a 26 mil grid connect the QFN central pad-
dle to the bottom side ground plane, as shown
in Figures 2 and 3.
Thermal Calculations
Layout
There are three types of losses associated with the
AAT1157: MOSFET switching losses, conduction
losses, and quiescent current losses. The conduc-
tion losses are due to the RDSON characteristics of
the internal P- and N-channel MOSFET power
devices. At full load, assuming continuous conduc-
tion mode (CCM), a simplified form of the total loss-
es is given by:
Figures 2 and 3 display the suggested PCB layout
for the AAT1157. The following guidelines should
be used to help insure a proper layout.
1. The input capacitor (C1) should connect as
closely as possible to VP (Pins 10, 11, and 12)
and PGND (Pins 1, 2, and 3).
2. C3-C4 and L1 should be connected as close-
ly as possible. The connection from L1 to the
LX node should be as short as possible.
Figure 2: Evaluation Board Top Side.
Figure 3: Evaluation Board Bottom Side.
1157.2005.11.1.4
9
AAT1157
1MHz 1.2A Buck DC/DC Converter
59kΩ. Values higher than this can cause stability
problems, while lower values can degrade light
load efficiency. For a 2.5V output with R4 set to
59kΩ, R3 is 187kΩ.
IO2 ⋅ (RDSON(HS) ⋅ VO + RDSON(LS) ⋅ (VIN - VO))
P =
VIN
+ (tsw ⋅ F ⋅ IO ⋅ VIN + IQ) ⋅ VIN
V
2.5V
0.6V
⎛
⎝
⎞
⎛
⎝
⎞
⎠
O
R3 =
-1 · R4 =
- 1 · 59kΩ = 187kΩ
Where IQ is the AAT1157 quiescent current.
V
⎠
REF
Once the total losses have been determined, the
junction temperature can be derived from the θJA for
the QFN package. Close attention should be paid to
the proper layout for the QFN package. Proper size
and placement of thermal routing vias below the
central paddle is necessary for good heat transfer to
other PCB layers and their ground planes. The θJA
for the QFN package with no connection to the cen-
tral paddle is 50°C/W. The actual θJA will vary with
the number and type of vias. The PCB board size,
number of board layers, and ground plane charac-
teristics also influence the θJA. A good thermal con-
nection from the paddle to the PCB ground plane
layers can significantly reduce θJA.
Table 1: Suggested Component Values.
Output
Voltage
(V)
Output
Capacitor
(C3-C4) (µF)
R3 for
R4 = 59kΩ
(kΩ)
L1
(µH)
0.8
1.0
1.2
1.5
1.8
2.5
3.3
1.5 - 2.6
1.5 - 3.3
2.2 - 3.3
2.2 - 4.7
3.0 - 4.7
3.0 - 4.7
2.2 - 4.7
3x 22
2x 22
2x 22
2x 22
2x 22
2x 22
22
19.6
39.2
59
88.7
118
187
267
TJ = P · ΘJA + TAMB
Buck-Boost Output
Figure 4 shows how to configure the AAT1157 in a
buck boost configuration with an external MOSFET
and Schottky diode. The converter has a 3.3V
600mA output with an input voltage ranging from
2.7V to 5.5V.
Adjustable Output
Resistors R3 and R4, as shown in Figure 1, force
the output to regulate higher than the 0.6V refer-
ence voltage level. The optimum value for R4 is
VIN 2.7V to 5.5V
U1
VO 3.3V/600mA
R2
AAT1157
267k
12
11
10
7
4
VP
OUT
15
14
13
16
3
L1
3.0µH
R1
100
VP
LX
D1
VP
LX
MBRM120L
EN
LX
C1
22µF
9
Q1
Si2302ADS
VCC
N/C
N/C
N/C
C3,C4
2x 22µF
R3
59.0k
6
C2
0.1µF
PGND
PGND
8
2
5
1
SGND PGND
L1 SumidaCDRH5D28-3R0
C1 Murata 22µF 10V X7R 1210 GRM32ER71A226KE20L
C3,C4 MuRata 22µF 6.3V X5R 0805 GRM21BR60J226ME39L
Figure 4: AAT1157 Buck Boost Converter.
10
1157.2005.11.1.4
AAT1157
1MHz 1.2A Buck DC/DC Converter
Design Example
Specifications
IOUT
1.2A
IRIPPLE 330mA
VOUT 2.5V
VIN
FS
3.0V to 4.2V
1MHz
TAMB = 85°C
Maximum Input Capacitor Ripple:
V
V
O
⎛
⎞
⎠
O
IRMS = IO ·
· 1-
= 0.59Arms
⎝
V
V
IN
IN
P = esr · IRMS2 = 5mΩ · 0.592 A = 1.7mW
Inductor Selection:
VOUT
∆IPP ⋅ F
⎛
⋅ 1 -
⎝
VOUT
⎞
2.5
V
2.5V
⎞
4.2V
⎠
⎛
⎝
L =
=
⋅
1 -
= 3.07µH
⎠
VIN
0.33A ⋅ 1MHz
Select Sumida inductor CDRH5D28 3.0µH.
⎛
⎞
2.5V
⎠
4.2V
VO
L ⋅ F
VO
VIN
2.5
V
⎛
⎞
⎠
∆I =
⋅ 1 -
⎝
=
⋅ 1-
= 340mA
⎝
3.0µH ⋅ 1MHz
∆I
2
IPK = IOUT
+
= 1.2A + 0.17A = 1.37A
P = IO2 ⋅ DCR = (1.2A)2 ⋅ 31mΩ = 45mW
Output Capacitor Ripple Current:
(VOUT) · (VIN - VOUT
)
1
2.5V · (4.2V - 2.5V)
1
·
= 97.4mArms
IRMS
=
·
=
3.0µH · 1MHz · 4.2V
L·F·V
2· 3
2· 3
IN
Pesr = esr · IRMS2 = 5mΩ · (97.4mA)2 = 47.4µW
1157.2005.11.1.4
11
AAT1157
1MHz 1.2A Buck DC/DC Converter
AAT1157 Dissipation and Junction Temperature Estimate:
IO2 · (RDSON(HS) · VO + RDSON(LS) · (VIN -VO))
PTOTAL
=
=
+ (tsw · F · IO + IQ) · VIN
VIN
1.2A2 · (0.17Ω · 2.5V + 0.16Ω · (4.2V - 2.5V))
+ (20nsec · 1MHz · 1.2A + 275µA) · 4.2V
4.2V
= 341mW
TJ(MAX) = TAMB + ΘJA · PTOTAL = 85°C + 50°C/W · 0.341W = 102°C
Surface Mount Inductors
Value
(µH)
Max DC
DCR
Size (mm)
L x W x H
Manufacturer Part Number
Current (A) (mΩ)
Type
Sumida
Sumida
Sumida
TaiyoYuden
Sumida
Sumida
Sumida
Sumida
Sumida
Sumida
MuRata
MuRata
CDRH5D28-2R6
CDRH5D28-3R0
CDRH5D28-4R2
NPO5DB4R7M
2.6
3.0
4.2
4.7
2.2
2.7
3.3
4.1
2.2
3.3
4.7
4.7
2.6
2.4
18
24
31
38
31
43
49
57
59
85
41
25
5.7x5.7x3.0
5.7x5.7x3.0
5.7x5.7x3.0
5.9x6.1x2.8
5.0x5.0x3.0
5.0x5.0x3.0
5.0x5.0x3.0
5.7x5.7x2.0
4.0x4.0x1.8
4.0x4.0x1.8
5.0x5.0x4.7
6.3x6.3x4.7
Shielded
Shielded
Shielded
Shielded
Shielded
Shielded
Shielded
Shielded
Shielded
Shielded
Non-Shielded
Shielded
2.2
1.4
CDRH4D28-2R2
CDRH4D28-2R7
CDRH4D28-3R3
CDRH5D18-4R1
CDRH3D16/HP-2R2
CDRH3D16/HP-3R3
LQH55DN4R7M03
LQH66SN4R7M03
2.04
1.6
1.57
1.95
2.3
1.8
2.7
2.2
Surface Mount Capacitors
Value
(µF)
Voltage
(V)
Manufacturer
Part Number
Temp. Co.
Case
MuRata
MuRata
MuRata
GRM21BR60J106ME01L
GRM21BR60J226ME01L
GRM31CR60J106KA01L
10
22
10
6.3
6.3
6.3
X5R
X5R
X5R
0805
0805
1206
12
1157.2005.11.1.4
AAT1157
1MHz 1.2A Buck DC/DC Converter
Ordering Information
Output Voltage
Package
Marking1
Part Number (Tape and Reel)2
AAT1157IVN-T1
FB = 0.8V, Adjustable ≥ 0.8V
QFN33-16
OEXYY
All AnalogicTech products are offered in Pb-free packaging. The term “Pb-free” means
semiconductor products that are in compliance with current RoHS standards, including
the requirement that lead not exceed 0.1% by weight in homogeneous materials. For more
information, please visit our website at http://www.analogictech.com/pbfree.
Package Information
QFN33-16
0.230 0.05
Pin 1 Identification
1
5
Pin 1 Dot By Marking
13
9
3.000 0.05
0.500 0.05
Top View
Bottom View
0.203 0.0254
Side View
All dimensions in millimeters.
1. XYY = assembly and date code.
2. Sample stock is generally held on part numbers listed in BOLD.
1157.2005.11.1.4
13
AAT1157
1MHz 1.2A Buck DC/DC Converter
© Advanced Analogic Technologies, Inc.
AnalogicTech cannot assume responsibility for use of any circuitry other than circuitry entirely embodied in an AnalogicTech product. No circuit patent licenses, copyrights, mask work rights,
or other intellectual property rights are implied. AnalogicTech reserves the right to make changes to their products or specifications or to discontinue any product or service without notice.
Customers are advised to obtain the latest version of relevant information to verify, before placing orders, that information being relied on is current and complete. All products are sold
subject to the terms and conditions of sale supplied at the time of order acknowledgement, including those pertaining to warranty, patent infringement, and limitation of liability. AnalogicTech
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trol techniques are utilized to the extent AnalogicTech deems necessary to support this warranty. Specific testing of all parameters of each device is not necessarily performed.
Advanced Analogic Technologies, Inc.
830 E. Arques Avenue, Sunnyvale, CA 94085
Phone (408) 737-4600
Fax (408) 737-4611
14
1157.2005.11.1.4
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