LX7176ACLQ-TR [MICROSEMI]
Switching Regulator, Voltage-mode, 4A, 1750kHz Switching Freq-Max, PQCC12,;
| 型号： | LX7176ACLQ-TR |
| 厂家： | 
Microsemi |
| 描述： | Switching Regulator, Voltage-mode, 4A, 1750kHz Switching Freq-Max, PQCC12, 开关 |
| 文件： | 总15页 (文件大小：1560K) |
| 中文： | 中文翻译 | 下载： | 下载PDF数据表文档文件 |
LX7176A
4A Step-Down-Regulator
Production Datasheet
Description
Features
The LX7176A is a 4A step-down regulator with
integrated MOSFETs packaged in a space saving QFN12
2mm x 2mm for today’s mobile devices. It uses an ultra
fast, constant frequency hysteretic control method to
minimize external filter components while maintaining
excellent regulation. The LX7176A reference voltage is
0.6V.
0-4A Step-down Regulator
Operational Input Supply Voltage Range:
3V-5.5V (short durations to 6.5V.)
Hysteretic control offers best transient
response
CCM switching at a constant 1.65MHz
Automatically switches to DCM switching
The LX7176A operates from 3V to 5.5V rails and outputs
0.6V to 100% of the input voltage.
under light loads to improve efficiency
100% Duty Ratio Operation
Cycle-by-cycle current limiting protects against over-
current conditions. Hiccup mode provides protection for
Input under voltage and over voltage
protection
heavy over-load or short-circuit faults.
Thermal
protection shuts down the regulator under over-
temperature conditions. Over voltage conditions will
immediately shut off the output to protect against
permanent damage. The LX7176A automatically restarts
when all fault conditions are cleared. Internal soft start
circuitry limits start up inrush currents.
Enable and Power Good Function
Internal soft-start
Cycle-by-Cycle Over Current Protection
Hiccup Mode protects against short circuit
faults
RoHS Compliant
SW
0.47µH
VIN
VOUT
GND
1
2, 11
PVIN
VIN
SW
FB
GND
10
22µF, X5R
Applications
R1
R2
10µF
X5R
10µF
X5R
7
LX7176A
8
9
EN
High Performance HDD
LCD TV
6
5
OUT
NC
500k
PGOOD
Notebook/Netbook
Server and Workstations
Video Cards
PGND
3, 12
AGND
4
PGOOD
PoE Powered Devices Smart Phone
Figure 1: Typical Application Diagram
Copyright © 2013
Rev. 1.2 09/21/15
Microsemi
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Analog Mixed Signal Group
One Enterprise Aliso Viejo, CA 92656 USA 1-800-713-4113, 1-949-380-6100, fax 1-949-215-4996
LX7176A
4A Step-Down-Regulator
Production Datasheet
Pin Configuration and Pinout
• 76A
YWWL
• Pin 1 Indicator, YWWL = Year/Week/Lot Code
RoHS / Pb-free Matte Tin Pin Finish
Figure 2: Pinout
Ordering Information
Ambient
Temperature
Packaging
Type
Package
Part Number
LX7176ACLQ
Type
Bulk
0°C to 85°C
RoHS compliant, Pb-free QFN 2x2mm 12L
LX7176ACLQ-TR Tape and Reel
Thermal Properties
Thermal Resistance(θJA)
Typ
Units
QFN 2x2mm 12L
30
°C/W
Note: The JA number assumes no forced airflow. Junction Temperature is calculated using TJ = TA + (PD x JA). In particular,
θJA is a function of the PCB construction. The stated number above is for a four-layer board in accordance with JESD-51
(JEDEC).
Copyright © 2013
Rev. 1.2 09/21/15
Microsemi
Analog Mixed Signal Group
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LX7176A
4A Step-Down-Regulator
Production Datasheet
Pin Description
Pin Number Pin Designator Description
Supply Voltage. Bypass PVIN to ground plane as close as possible to
the IC.
1, 10
PVIN
2, 11
3, 12
4
SW
PGND
AGND
Switch Output. Drives the external L-C filter.
Power Ground. Connect to ground plane.
Analog Ground. Connect to ground plane.
No connect pin. Leave floating. Serves as SCL when accessing the
serial port.
5
NC
Output Voltage Sense Pin – This pin monitors the output voltage.
Serves as SDA when accessing the serial port. Digital signals at this
pin will be capacitively coupled onto FB and disturb the output
voltage.
6
OUT
Feedback – Analog input, monitors the output voltage either directly
7
8
FB
or through a resistor divider.
EN
Enable – Digital input. Force high to enable the IC.
Power Good – Open drain digital output. Pulls low to indicate a fault
condition. Requires an external pull up resistor. Also used to
monitor selected internal signals.
9
PG
Copyright © 2013
Rev. 1.2 09/21/15
Microsemi
Analog Mixed Signal Group
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LX7176A
4A Step-Down-Regulator
Production Datasheet
Block Diagram
Figure 3: Block Diagram
Copyright © 2013
Rev. 1.2 09/21/15
Microsemi
Analog Mixed Signal Group
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One Enterprise Aliso Viejo, CA 92656 USA 1-800-713-4113, 1-949-380-6100, fax 1-949-215-4996
LX7176A
4A Step-Down-Regulator
Production Datasheet
Absolute Maximum Ratings
Performance is not necessarily guaranteed over this entire range. These are maximum stress ratings
only. Exceeding these ratings, even momentarily, can cause immediate damage, or negatively impact
long-term operating reliability.
Parameter
PVIN, EN, PG, OUT, FB, SW to PGND
AGND to PGND
SW to PGND (Shorter than 50ns)
Junction Temperature Range
Storage Temperature Range
Peak Lead Soldering Temperature (40s, reflow)
Min
-0.3
-0.3
-2
0
-65
Max
7
0.3
7
150
Units
V
V
V
°C
°C
°C
150
260 (+0, -5)
Operating Ratings
Performance is generally guaranteed over this range as further detailed below under Electrical
Characteristics.
Parameter
Input Voltage
Output Voltage
Output Current (VIN = 3V to 5V)
Min
3.0
0.6
0
Max
5.5
5.5
4
Units
V
V
A
Ambient Temperature
Note: Corresponding Max Junction Temperature is 125°C
0
85
°C
Copyright © 2013
Rev. 1.2 09/21/15
Microsemi
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Analog Mixed Signal Group
One Enterprise Aliso Viejo, CA 92656 USA 1-800-713-4113, 1-949-380-6100, fax 1-949-215-4996
LX7176A
4A Step-Down-Regulator
Production Datasheet
Electrical Characteristics
Unless otherwise specified, the following specifications apply over the operating ambient temperature
of 0°C ≤ TA ≤ 85°C with the following test conditions: PVIN = 5V. Typical parameters refers to TJ = 25°C.
VOUT = 0.9V. VOUT is disconnected from FB for open loop tests. Iload = 0,. EN=high, GBD specifications are
guaranteed by design and/or characterization and are not tested on a production basis.
Symbol
PVIN
IQPSM
Parameter
Conditions
Enable PSM
Min
Typ
Max
Units
PSM Bias Current
Input Current at
Shutdown
280
0.1
µA
µA
ISLEEP
EN = low, TJ = 25°C
3
Under Voltage
Rising Threshold
UVLORISING
PVIN rising
2.8
V
V
V
UVLOHYST UVLO Hysteresis
PVIN falling
PVIN rising. Will also trigger on
DV/DT > 1V/µs
0.2
6.1
Over Voltage
OVPR
Rising Threshold
Over Voltage
OVPF
PVIN falling
5.5
5.85
V
Falling Threshold
VREF
VREF
Reference Voltage
VREF Slew Rate
Hiccup Time
0.594
0.6
3.75
1.2
0.606
0.909
V
TSS
mV/µs
ms
THICCUP
VOUT
VOUT is set to 0.9V with 0.1%
feedback resistors. PVIN = 5V, ,
0°C to 85°C.
VOUT
VOUT Accuracy
0.891
0.9
V
ILOAD = 0.1A
0.01
0.06
-0.06
VIN from 3V to 5V,
(in DCM)
Line Regulation
Load Regulation
VOUT = 0.9V. Note
%/V
ILOAD = 2.5A
(in CCM)
VOUT = 0.9V, IOUT = 0A to 4A .
1
VOUTLR
%/A
µA
Note 1
FBIL
FB Input Current
FB Under Voltage
Threshold
1
VOUT below this threshold will
initiate a hiccup sequence.
FBUV
80
%VREF
Output Discharge
Resistance
RDISC
SW
EN = low
80
314
500
Ω
High Side On
Resistance
RDSON_H
46
mΩ
Copyright © 2013
Rev. 1.2 09/21/15
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Analog Mixed Signal Group
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LX7176A
4A Step-Down-Regulator
Production Datasheet
Symbol
RDSON_L
Parameter
Low Side On
Resistance
Conditions
Min
Typ
Max
Units
21
mΩ
Rated Output
Current
IRATED
ICL
PVIN = 3V to 5V. Note 1
4
A
A
Peak inductor current. PVIN = 3V
to 5V . Note 1
Current Limit
6.3
7.4
9
Thermal
TSH
TH
Shutdown
Threshold¹
Thermal
Note 1
150
°C
°C
Shutdown
Hysteresis¹
Note 1
20
PWM Switching
Frequency
FSW
VOUT / VIN ≥ 35%, T=25°C, Note 1
1.55
0.4
1.65
1.75
MHz
EN
VIH
VIL
IIN
Input High
Input Low
Input Current
1.2
1
V
V
µA
0.01
90
PG
PGOOD VOUT
Lower Threshold
PGOOD VOUT
Upper Threshold
Hysteresis
PGOOD Pull-down
Resistance
VPG90
VOUT rising, percentage of VREF
%
VPG110
VPGHY
VOUT falling, percentage of VREF
Percentage of VREF
110
5
%
%
Ω
PGRDSON
13
50
1
PGOOD Leakage
Current
PGILEAK
TJ = 25°C
0
µA
Note 1: These parameters are not tested, but guaranteed by design and characterization.
Copyright © 2013
Rev. 1.2 09/21/15
Microsemi
Analog Mixed Signal Group
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LX7176A
4A Step-Down-Regulator
Production Datasheet
Typical Performance Curves (Efficiency)
100%
90%
80%
70%
60%
50%
40%
30%
VOUT = 0.9V
VOUT = 1.8V
VOUT = 3.3V
1
10
100
1000
Load Current (mA)
Figure 4: LX7176A Efficiency with VIN = 5V, L = 0.47µH, COUT = 22µF
Copyright © 2013
Rev. 1.2 09/21/15
Microsemi
Analog Mixed Signal Group
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LX7176A
4A Step-Down-Regulator
Production Datasheet
Step Response(Load Current = 1.5A to 4A, L = 0.47μH, COUT = 22μF)
Typical Performance Curves
Figure 5. Step Load
Figure 6. Step Load Rising Edge
Figure 7. Step Load Falling Edge
Copyright © 2013
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Microsemi
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Analog Mixed Signal Group
One Enterprise Aliso Viejo, CA 92656 USA 1-800-713-4113, 1-949-380-6100, fax 1-949-215-4996
LX7176A
4A Step-Down-Regulator
Production Datasheet
Theory of Operation
Basic Operation
a hiccup sequence will be initiated where both
output switches are shut off for 1.2ms before
initiating another soft start. This protects against a
crowbar short circuit. FB under voltage detection is
not active during startup.
The LX7176A compares the FB voltage to an
internal reference, VREF. When FB is lower than
Vref, the upper switch turns on and the lower
switch turns off. When FB is higher than VREF, the
upper switch turns off and the lower switch turns
on. An internal ramp and a frequency control loop
keep the switching frequency constant when in
constant conduction mode (CCM) over a wide
range of output capacitor values and parasitic
components (i.e. ESR, ESL).
Setting the Output Voltage
The reference voltage is 0.6V
R1
R2
VOUT
1 VREF
(1)
At light loads, the converter automatically reduces
the switching frequency to optimize conversion
efficiency.
Where R1 is high side feedback divider resistor, R2 is
low side feedback divider resistor, VREF is 0.6V.
Startup
The LX7176A is enabled when EN is high and PVIN
rises above the UVLO threshold. At start up, after
all the internal bias voltages and currents stabilize,
VREF ramps up from 0V to the target voltage at the
defined slew rate. While VREF ramps, PGOOD is
held low. At the end of the ramp time, PGOOD is
allowed to go high if the FB has reached the
PGOOD rising threshold.
Over Current Protection
The LX7176A protects against all types of short
circuit conditions. Cycle by cycle over current
protection turns off the upper switch when the
current exceeds the ICL threshold. When this
occurs, the upper switch is kept off for about
360ns before being allowed to turn on again. After
startup, if FB drops below the FBUV threshold,
Copyright © 2013
Rev. 1.2 09/21/15
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Analog Mixed Signal Group
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LX7176A
4A Step-Down-Regulator
Production Datasheet
Recommended Output Filter Components
The following tables show recommended feedback
component values (RHIGH, RLOW, Cff) for different
input/output voltages, power inductor (L), and
output capacitance (C) values that result in
optimum closed loop response of the regulator in
each case. The estimated crossover frequency is
also shown in the table in each case. If the L*C
factor exceeds a certain number the regulator
would run with low phase margin, or become
unstable. The L and C range provided in the table
provides 30°, or higher of phase margin. Therefore,
it is not recommended to increase L*C factor
beyond what is given in the table.
It is a good practice to determine L such that the
peak-to-peak inductor ripple current in continuous
conduction mode operation is roughly equal to 30%
of converter’s rated output current. In general,
increasing the inductance slows down the closed
loop response of the regulator. Hence, for
applications that require fast line/load transient
response, lower inductance values should be
preferred over larger ones. Output capacitance can
be determined based on desired output ripple
voltage staying within the limits provided in the
table depending on the inductance value.
F
VIN
(V)
VOUT
(V)
L
COUT
(µF)
RHIGH
(kΩ)
RLOW
(kΩ)
Cff
(pF)
crossover
(kHz)
(µH)
4x22
3x22
2x22
1x22
5x22
4x22
3x22
2x22
1x22
5x22
4x22
3x22
2x22
1x22
5x22
4x22
3x22
2x22
1x22
5x22
4x22
3x22
2x22
1x22
70
47
83
2.2
1.5
33
12
100
150
73
27
12
22
12
10
0
84
100
120
200
92
110
130
170
300
140
170
220
280
575
180
220
280
400
625
60
120
1.0
5.0
0.9
0.47
0.33
6.8
0
L
VIN
VOUT
1
2, 11
PVIN
VIN
SW
GND
10
Cout
Cff
Rhigh
Rlow
GND
10µF
X5R
10µF
X5R
7
FB
7.5
15
LX7176A
8
9
EN
6
5
OUT
NC
500k
PGOOD
PGND
3, 12
AGND
4
PGOOD
Copyright © 2013
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LX7176A
4A Step-Down-Regulator
Production Datasheet
Recommended Output Filter Components - Continued
F
F
VIN
(V)
VOUT
(V)
L
COUT
(µF)
RHIGH
(kΩ)
RLOW
(kΩ) (pF)
Cff
VIN VOUT
L
COUT
(µF)
RHIGH RLOW
Cff
crossover
(kHz)
crossover
(kHz)
(µH)
(V)
(V)
(µH)
(kΩ)
(kΩ) (pF)
33
12
27
2x22
1x22
3x22
2x22
1x22
5x22
4x22
3x22
2x22
1x22
5x22
4x22
3x22
2x22
1x22
5x22
4x22
3x22
2x22
1x22
76
110
74
5x22
4x22
2x22
3x22
1x22
5x22
4x22
3x22
2x22
1x22
5x22
4x22
3x22
2x22
1x22
5x22
4x22
3x22
2x22
1x22
5x22
4x22
3x22
2x22
1x22
49
57
2.2
1.5
12
2.2
1.5
70
90
85
12
6.8
140
68
150
58
22
78
68
1.0
93
6.8
84
120
190
100
120
150
180
325
130
150
190
240
475
12
120
200
77
240
120
3.0
0.9
60
120
10
0
6.8
0
92
0.47
0.33
5.0
1.8
1.0
120
130
260
110
130
180
190
475
150
190
260
220
500
6.8
0
0.47
0.33
0
120
240
60
60
120
0
30
Copyright © 2013
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LX7176A
4A Step-Down-Regulator
Production Datasheet
Recommended Output Filter Components - Continued
F
F
VIN VOUT
(V) (V)
L
COUT
(µF)
RHIGH
(kΩ)
RLOW
(kΩ) (pF)
Cff
VIN VOUT
L
COUT
(µF)
RHIGH RLOW
Cff
crossover
(kHz)
crossover
(kHz)
(µH)
(V)
(V)
(µH)
(kΩ)
(kΩ) (pF)
5x22
4x22
3x22
2x22
1x22
5x22
4x22
3x22
2x22
1x22
5x22
4x22
3x22
2x22
1x22
5x22
4x22
3x22
2x22
1x22
5x22
4x22
3x22
2x22
1x22
36
42
5x22
4x22
2x22
3x22
1x22
5x22
4x22
3x22
2x22
1x22
5x22
4x22
3x22
2x22
1x22
5x22
4x22
3x22
2x22
1x22
5x22
4x22
3x22
2x22
1x22
58
12
67
2.2
1.5
2.2
1.5
81
50
110
170
75
60
6.8
6.8
100
42
22
87
49
100
140
240
100
120
140
190
325
170
200
240
350
450
220
260
325
475
525
60
79
540
120
140
55
6.8
64
5.0
3.3
1.0
33
3.0 1.8V
1.0
240
120
79
87
0
0
150
76
33
0.47
0.33
89
0.47
0.33
110
160
350
97
225
540
135
50
120
30
0
22
120
150
240
525
0
0
Copyright © 2013
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LX7176A
4A Step-Down-Regulator
Production Datasheet
Package Dimensions
QFN 2x2mm 12L Package
D2
10
MILLIMETERS
INCHES
D
L
Dim
MIN
MAX
MIN
MAX
A
A3
B
0.80
1.00
0.031
.039
9
8
7
6
1
2
3
4
b
0.20 REF
0.008 REF
0.20
0.30
0.008
0.012
E
D
1.90
2.10
0.075
0.083
e
D2
E
0.50BSC
0.02BSC
1.90
2.10
0.075
0.083
5
Top View
Side View
e
0.50 BSC
0.020 REF
b
L
0.30
0.45
0.012
0.018
Bottom View
A
Note:
1. Dimensions do not include mold flash or
protrusions; these shall not exceed 0.155mm
(.006”) on any side. Lead dimension shall not
include solder coverage.
A3
2. Dimensions are in millimeters, inches for
reference only.
Recommended Footprint
Copyright © 2013
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Analog Mixed Signal Group
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LX7176A
4A Step-Down-Regulator
Production Datasheet
2.20mm
0.55mm
0.50mm
0.55mm
2.20mm
0.30mm
0.70mm
Disclaimer:
This PCB land pattern recommendation is based on information available to Microsemi by its suppliers. The actual land pattern to be used could be different depending on the materials and
processes used in the PCB assembly, end user must account for this in their final layout. Microsemi makes no warranty or representation of performance based on this recommended land pattern
PRODUCTION DATA – Information contained in this document is pre-production data and is
proprietary to Microsemi. It may not be modified in any way without the express written
consent of Microsemi. Product referred to herein is offered in pre-production form only and
may not have completed Microsemi’s Quality Assurance process for Release to Production.
Microsemi reserves the right to change or discontinue this proposed product at any time.
Copyright © 2013
Rev. 1.2 09/21/15
Microsemi
Analog Mixed Signal Group
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