LX7175CLD-TR [MICROSEMI]
Switching Regulator, Voltage-mode, 3.5A, 1650kHz Switching Freq-Max, PDSO10, DFN-10;
| 型号： | LX7175CLD-TR |
| 厂家： | 
Microsemi |
| 描述： | Switching Regulator, Voltage-mode, 3.5A, 1650kHz Switching Freq-Max, PDSO10, DFN-10 开关 光电二极管 输出元件 |
| 文件： | 总16页 (文件大小：1037K) |
| 中文： | 中文翻译 | 下载： | 下载PDF数据表文档文件 |
LX7175
3V-5.5V, 3.5A Step Down
PWM Switching Regulator
Features
. 3.5A Step-down Regulator
Description
. Operational Input Supply Voltage Range:
LX7175 is a step-down PWM Switching Regulator
IC with integrated high side P-CH and low side N-
CH MOSFETs. The IC operates using a hysteretic
3V-5.5V
. Integrated PMOS and NMOS
. Load Current from zero to 3.5A
. 1.4MHz Switching Frequency
control topology with
a
full load switching
frequency of 1.4MHz allowing small output filter
components while maintaining excellent dynamic
load response.
. SKIP Pulse to Improve Light Load
Efficiency
The operational input voltage range of LX7175 is
from 3V to 5.5V and it has two modes of operation
selected externally by MODE pin. When MODE
pin is high, it operates in continuous PWM
operation and when it is tied low, it operates in
Power Save Mode (PSM) with automatic transition
between PWM and PSM mode depending on the
load current. This allows the converter’s efficiency
to remain high when load current drops.
. Open VReg Type 0 LV Compatible
. Input UVLO Protection
. Enable Pin
. Power Good
. Internal Soft-start
. Cycle-by-Cycle Over Current Protection
. Latch Off Operation Under Output Short.
. RoHS Compliant for Pb-free
In the shutdown mode, the IC’s current consumption
is reduced to less than 1µA and the output capacitor
is discharged.
Applications
. Small Battery Operated Devices
. HDD
Other features of the part are: a) cycle-by-cycle
current limit followed by latch off, b) thermal
protection with hysteresis, c) internal digital soft
start, d) and Power Good function.
. Set-Top Box
. LCD TV’s
. Notebook/Netbook
. Routers
. Video Cards
. PC Peripherals
. PoE Powered Devices
VIN
CVIN
10µF, X5R
2, 3
VIN
Rmode
L
RPgood
VOUT
8
6, 7
MODE
SW
FB
1µH
R1
1%
COUT
2x22µF, X5R
C1
LX7175
9
1
PGOOD
R2
1%
EN
10
4, 5
EN
GND
on
off
PAD
Figure 1 · Typical Application of LX7175
July 2013 Rev. 1.2
www.microsemi.com
© 2013 Microsemi Corporation
1
3V-5.5V, 3.5A Step Down PWM Switching Regulator
Pin Configuration and Pinout
1
10
9
FB
EN
2
PGOOD
MODE
SW
VIN
Thermal
Pad
(GND)
3
4
5
8
VIN
GND
GND
7
6
SW
Figure 2 · Pinout DFN 3x3 10L Top View
Marking: Line1 7175
Line2 Date / Lot Code
Line3 * MSC ( * is the pin 1 dot )
Ordering Information
Ambient
Type
Package
Part Number
Packaging Type
Temperature
LX7175CLD
Bulk / Tube
RoHS Compliant,
-10°C to 85°C
DFN 3X3 10L
Pb-free
LX7175CLD-TR
Tape and Reel
2
Pin Description
Pin Description
Pin Number
Pin Designator
Description
Voltage feedback pin. Connect to the output terminal through a resistor
divider network to set the output voltage of the regulator to the desired
voltage.
1
FB
Input voltage terminal of the regulator. A minimum of 10µF, X5R type
ceramic capacitor must be connected as close as possible from this pin to
GND plane to insure proper operation.
2, 3
VIN
4, 5
6, 7
GND
SW
Ground pins for the power stage.
Switch-node pin. Connect the output inductor between this pin and output
capacitor.
When this pin is connected to GND, the chip will go into variable frequency
hysteretic mode that gradually reduces switching frequency as the load is
reduced. When it is connected to VIN, it operates in constant frequency
hysteretic mode, and will remain in continuous conduction mode. In this
mode the low side MOSFET is not turned off when the current in the
inductor reverses direction to pull current from the load.
8
MODE
Power-good pin. This is an open-drain output and should be connected to
a voltage rail (for example, VIN) with an external pull-up resistor. During
the power on sequence, this pin switches from Low to High state when the
FB voltage exceeds the power good threshold and the internal soft start
has finished its operation. It will be pulled low, when the FB falls below the
power good threshold minus the hysteresis. It will turn back on, when the
pull FB rises again above the threshold.
9
PGOOD
Pulling this pin higher than 2V will enable the regulator. When pulled low,
the regulator will turn off.
10
EN
For good thermal connection, this PAD must be connected using thermal
VIAs to the GND plane and to the LAND pattern of the IC.
Thermal PAD
3
3V-5.5V, 3.5A Step Down PWM Switching Regulator
Block Diagram
2,3
VIN
PGOOD
9
CHARGE
POWER
GOOD
PHASE DET
PUMP
HIGH SIDE
DRIVER
OSC
SW
6,7
MODE
CURRENT
LIMIT
PWM
CONTROL
8
FB
1
LOW SIDE
DRIVER
TON, TOFF
CONTROL
-
+
EN
ENABLE
10
GND
4,5
VREF+
SOFT START
DIODE
EMULATOR
SOFT
DISHARGE
LX7175
PAD
Figure 3 · Simplified Block Diagram of LX7175
4
Absolute Maximum Ratings
Absolute Maximum Ratings
Min
-0.3
-0.3
-4
Max
7
Units
V
Parameter
VIN, EN, FB, PGOOD, MODE to GND
SW to GND
7
V
SW to GND (Shorter than 15ns)
Maximum Junction Temperature
Storage Temperature
7
V
150
150
°C
°C
-65
Peak Package Solder Reflow Temperature
(40s, reflow)
260 (+0, -5)
°C
Note: 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
Operating Ratings
Min
3.0
0.8
-10
0
Max
5.5
3.3
85
Units
V
VIN
VOUT
V
Ambient Temperature
Output Current
°C
A
3.5
Thermal Properties
Thermal Resistance
Typ
Units
θJA
41.2
°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).
Electrical Characteristics
Note: The following specifications apply over the operating ambient temperature of -10C ≤ TA ≤ 85C except
where otherwise noted with the following test conditions: 3.0 < VIN < 5.5V. Typical parameters refer to
TJ = 25°C, VIN = 5V.
Symbol
Parameter
Test Condition
Min
Typ
Max
Units
Operating Current
IQ
Input Current
ILOAD = 0, MODE = GND
EN = GND, TA = 25°C
200
0.1
500
1
µA
µA
Input Current at Shut
Down
IIN
5
3V-5.5V, 3.5A Step Down PWM Switching Regulator
Symbol
Parameter
Test Condition
Min
Typ
Max
Units
VIN INPUT UVLO
VIN
Under Voltage Lockout VIN rising
UVLO Hysteresis
2.4
2.8
V
VHYS
250
mV
FEEDBACK
TA = 25°C
0.788 0.800 0.812
V
V
Feedback Voltage
VREF
IFB
Internal Reference
0 < TJ < 125°C
0.782
0.818
10
FB Pin Input Current
nA
VIN from 3V to 5.5V, MODE = High,
ILOAD = 0.1A, VOUT = 1V ,
Line Regulation
Load Regulation
0.065
%
L = 0.68µH, COUT = 44µF. GBD
VIN = 5V, MODE = High
VOUT = 1V
0.06
0.08
ILOAD = 0 to 3.5A,
L = 0.68µH, COUT = 44µF.
GBD
%/A
VOUT = 3.3V
VOUT = 1V
VIN = 5V, MODE = Low
ILOAD = 0.2A to 3.5A,
L = 0.68µH, COUT = 44µF.
GBD
0.075
0.11
%/A
mV
VOUT = 3.3V
Load from 0.1A to 1.5A, Tr = Tf = 1µs,
VOUT = 1V, L = 0.68µH, COUT = 44μF,
MODE = High. GBD
Transient Response
FB UVLO Threshold
±35
FB UVLO
VFBULVO
40%
50%
VREF
OUTPUT DEVICE
RDSON_H RDSON of High Side
RDSON_L
55
40
100
65
mΩ
mΩ
RDSON of High Side
Current Limit
VIN = 5V.
0 < TJ < 125°C. GBD
4.5
5.9
5.3
7.3
IL
A
VIN = 3V.
3.89
6.74
Thermal Shut Down
Threshold
TSH
TH
GBD
GBD
140
163
27
185
°C
°C
Hysteresis
OSCILLATOR
f
Switching Frequency
MODE = High
1.25
0.3
70
1.4
1.65
0.6
MHz
MHz
%
In Boundary Conduction Mode, In Hysteretic
Mode (The PLL is off)
FHYST
Switching Frequency
Maximum Duty Cycle
0.445
DMAX
SOFT START
From EN going high to VOUT reaches
regulation.
TSS
Soft Start Time
0.8
1.4
1.8
ms
6
Electrical Characteristics
Symbol
Parameter
Test Condition
Min
Typ
Max
Units
MODE
MVIH
Input High
1.1
V
MVIL
Input Low
Input Bias
0.4
1
V
MVIH
0.01
µA
EN INPUT
ENVIH
ENVIL
ENH
Input High
1.1
V
V
Input Low
0.4
1
Hysteresis
0.1
V
ENII
Input Bias Current
0.01
µA
POWER-GOOD
Power-good Transition VFB rising, in percentage of output voltage
VPG
83
40
%
mV
Ω
High Threshold
set-point.
VPGHY
PGRDSON
Hysteresis
Either VFB rising or falling
Power-good Internal
FET RDSON
VIN = 5V, 0 < TJ < 125°C
100
1
PGOOD FET Leakage
Current
0.01
5
µA
µs
PGOOD Internal Glitch
Filter
OUTPUT DISCHARGE
Internal Discharge
80
300
600
Ω
Resistor
GBD Guaranteed by design, not production tested.
7
3V-5.5V, 3.5A Step Down PWM Switching Regulator
Typical Performance Curves (Efficiency & Line Regulation)
95
90
85
80
75
70
95
90
85
80
75
70
0
500
1000
1500
2000
2500
3000
3500
1
10
100
1000
Load Current (mA)
Load Current (mA)
VIN = 3.3V, VOUT = 0.9V
VIN = 3.3V, VOUT = 1.2V
VIN = 3.3V, VOUT = 1.8V
VIN = 5V, VOUT = 0.9V
VIN = 5V, VOUT = 1.2V
VIN = 5V, VOUT = 1.8V
VIN = 3.3V, VOUT = 0.9V
VIN = 3.3V, VOUT = 1.2V
VIN = 3.3V, VOUT = 1.8V
VIN = 5V, VOUT = 0.9V
VIN = 5V, VOUT = 1.2V
VIN = 5V, VOUT = 1.8V
Figure 4 · PSM Mode Efficiency
Figure 5 · PSM Mode Efficiency in Log Scale
100
90
80
70
60
50
40
30
20
10
0.91
0.905
0.9
0.895
0.89
2.75
3.25
3.75
4.25
4.75
5.25
5.75
1
10
100
1000
VIN (V)
Load Current (mA)
VIN = 3.3V, PSM
VIN = 5V, PSM
VIN = 3.3V, PWM
VIN = 5V, PWM
VOUT=0.9V
Figure 6 · PSM vs. PWM Efficiency with VOUT=1.8V
Figure 7 · Line Regulation VOUT = 0.9V (VOUT vs. VIN)
8
Typical Performance Curves (Line Regulation & Load Regulation)
Typical Performance Curves (Line Regulation & Load Regulation)
1.21
1.208
1.206
1.204
1.202
1.2
1.82
1.81
1.8
1.79
1.78
1.77
1.76
1.198
1.196
1.194
1.192
1.19
2.75
3.25
3.75
4.25
4.75
5.25
5.75
2.75
3.25
3.75
4.25
4.75
5.25
5.75
VIN (V)
VIN (V)
VOUT=1.2V
VOUT=1.8V
Figure 8 · Line Regulation VOUT = 1.2V (VOUT vs. VIN)
Figure 9 · Line Regulation VOUT = 1.8V (VOUT vs. VIN)
3.31
3.308
3.306
3.304
3.302
3.3
1.012
1.01
1.008
1.006
1.004
1.002
1
3.298
3.296
3.294
0.998
0
0.5
1
1.5
Load Curent (A)
MODE=LOW
2
2.5
3
3.5
0
0.5
1
1.5
Load Current (A)
MODE=LOW
2
2.5
3
3.5
MODE=HIGH
MODE=HIGH
Figure 10 · Load Regulation VIN = 5V, VOUT = 1.0V
Figure 11 · Load Regulation VIN = 5V, VOUT = 3.3V
(VOUT vs. Load Current)
(VOUT vs. Load Current)
9
3V-5.5V, 3.5A Step Down PWM Switching Regulator
Typical Performance Curves (Load Transient - VIN = 5V, VOUT = 1V)
Figure 12 · L = 0.68µH, COUT=44µF
Figure 13 · L = 0.68µH, COUT=44µF, Rising Edge
CH2: VOUT, CH4: IL
CH2: VOUT, CH4: IL
Figure 14 · L = 0.68µH, COUT=154µF
Figure 15 · L = 0.68µH, COUT=154µF Rising Edge
CH2: VOUT, CH4: IL
CH2: VOUT, CH4: IL
10
Typical Performance Curves (Start Up - VIN = 5V, VOUT = 1V)
Typical Performance Curves (Start Up - VIN = 5V, VOUT = 1V)
Figure 16 · Power up with no load, MODE = High
Figure 17 · Power up with resistive load, MODE = High
CH1: VIN, CH2: VOUT, CH3: PGOOD,
CH4: Inductor Current
CH1: VIN, CH2: VOUT, CH3: PGOOD,
CH4: Inductor Current
Figure 18 · Power up with no load, MODE = Low
Figure 19 · Power up with resistive load
CH1: VIN, CH2: VOUT, CH3: PGOOD,
CH4: Inductor Current
CH1: VIN, CH2: VOUT, CH3: PGOOD,
CH4: Inductor Current
11
3V-5.5V, 3.5A Step Down PWM Switching Regulator
Typical Performance Curves (Short Condition)
Figure 20 · Output Short 5V input 1V output
Figure 21 · Output Short 5V input 3.3V output
CH1: VIN, CH2: VOUT, CH3: PGOOD,
CH4: Inductor Current
CH1: VIN, CH2: VOUT, CH3: PGOOD,
CH4: Inductor Current
Figure 22 · Power into Short from VIN, VIN = 5V
Figure 23 · Power into Short from EN, EN = VIN = 5V
CH1: VIN, CH2: VOUT, CH3: PGOOD,
CH4: Inductor Current
CH1: VIN, CH2: VOUT, CH3: PGOOD,
CH4: Inductor Current
12
Typical Performance Curves (Output Voltage Ripple)
Typical Performance Curves (Output Voltage Ripple)
34
32
30
28
26
24
22
20
45
40
35
30
25
20
15
22
44
66
88
110
132
154
176
22
44
66
88
110
132
154
176
Output capacitance (µF)
Output capacitance (µF)
L=0.68uH, Vin=5V
L=0.68uH, Vin=3V
L=1.5uH, Vin=5V
L=1.5uH, Vin=3V
L=0.68uH
L=1.5uH
Figure 24 · No Load Peak to Peak Output Ripple
Figure 25 · No Load Peak to Peak Output Ripple
VOUT = 1V
VIN = 5V, VOUT = 3.3V
Figure 26 · No Load Peak to Peak Output Ripple
Figure 27 · Figure 26 Rising Edge Zoom In
CH2: VOUT
CH1: SW, CH2: VOUT, CH4: Inductor Current
VIN = 5V, VOUT = 3.3V,
VIN = 5V, VOUT = 3.3V,
L = 0.68µH, COUT = 154µF
L = 0.68µH, COUT = 154µF
13
3V-5.5V, 3.5A Step Down PWM Switching Regulator
Theory of Operation / Application Information
Basic Operation
The operation of the controller consists of comparing the VFB voltage to an internal reference.
When the VFB voltage is lower than the VREF, the upper switch turns on. When the VFB voltage is
higher than VREF, the upper switch turns off and the lower switch turns on. An internal ramp and
clock signal are used to stabilize the switching frequency and keep the VFB immune to the output
capacitor, Co, value or parasitic components (i.e. ESR, ESL).
Setting of the Output Voltage
The values of R1 and R2 are chosen so according to the following equation:
ꢄꢅ
(
)
ꢇ ꢈꢅ ꢉꢈ
ꢊꢋꢌ
ꢀꢁꢂ
ꢃ
ꢄꢆ
Startup
The reference is ramped up from zero voltage to 0.8V in 1.4ms. During this time, the PGOOD is
pulled low. When the reference reaches 0.8V, signaling the end of the soft start cycle, the PGOOD
pin will go high within 5μS.
Over Current Protection
The IC has the ability to protect against all types of short circuit conditions. It has cycle by cycle short
protection that turns off the upper MOSFET and ends the cycle when the current exceeds the OCP
threshold. When this occurs, the off-time is at least 200ns before the upper FET is turned on again.
This will clamp the current at the peak current threshold.
If the load requires more than the peak current threshold, the output voltage will drop since the current
is clamped. If the output drops below the feedback UVLO threshold, the device will latch off. The
enable pin can be cycled to restart the converter.
During the soft start sequence the current protection mechanism is different. If the peak current
threshold is exceeded during soft start, the upper FET is turned off for approximately 1μs. After 1μs,
the upper FET is turned back on. This will limit the peak output current at the peak current threshold.
During soft start the feedback UVLO alarm is not active, so in the event of a short, the peak current
will continue to trip until the end of the soft start period. After soft start, the feedback UVLO alarm will
be active and the latch-off event will occur.
Output Component Selection Table
The table below shows the recommended resistor and feedforward capacitor values for a given
output inductor and output capacitor value. See Figure 1 for the schematic location of R1, R2 and
C1.
VIN
VOUT
L
COUT
R1
R2
C1
1.5µH
0.68µH
1.5µH
1µH
0.68µH
1.5µH
0.68µH
1.5µH
1µH
180 pF
100 pF
68 pF
47pF
33 pF
330 pF
220 pF
150 pF
120pF
100 pF
180pF
47pF
154µF (7x22µF)
5V
1V
24.9k
100k
44µF (2x22µF)
154µF (7x22µF)
44µF (2x22µF)
5V
3V
3.3V
1V
100k
32.4k
0.68µH
1.5µH
1µH
154µF (7x22µF)
44µF (2x22µF)
24.9k
24.9k
100k
100k
14
DFN 3x3 10L PACKAGE OUTLINE DIMENSIONS
DFN 3x3 10L PACKAGE OUTLINE DIMENSIONS
D
e
MILLIMETERS
INCHES
L
Dim
MIN
0.70
0
MAX
0.80
0.05
MIN
MAX
A
A1
A3
b
0.0276
0
0.0315
0.0019
E
E2
0.20 REF
0.0079 REF
0.18
0.30
0.0071
0.0118
D
3.00 BSC
0.1181 BSC
Bottom
View
Top View
b
D2
e
2.25
0.50 BSC
3.00 BSC
2.50
0.0886
0.0984
D2
0.0197 BSC
0.1181 BSC
E
E2
L
1.50
0.30
1.75
0.50
0.0591
0.0118
0.0689
0.0197
A
A3
A1
Figure 28 · Package Dimensions
Note: 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
LAND PATTERN RECOMMENDATION
0.50mm
0.30mm
0.70mm
1.75mm
3.40mm
2.50mm
Figure 29 · Package Footprint
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 proprietary to Microsemi and is
current as of publication date. This document may not be modified in any way without the express
written consent of Microsemi. Product processing does not necessarily include testing of all
parameters. Microsemi reserves the right to change the configuration and performance of the product
and to discontinue product at any time.
15
Microsemi Corporation (NASDAQ: MSCC) offers a comprehensive portfolio of semiconductor
solutions for: aerospace, defense and security; enterprise and communications; and industrial
and alternative energy markets. Products include high-performance, high-reliability analog and
RF devices, mixed signal and RF integrated circuits, customizable SoCs, FPGAs, and
complete subsystems. Microsemi is headquartered in Aliso Viejo, Calif. Learn more at
www.microsemi.com.
Microsemi Corporate Headquarters
One Enterprise, Aliso Viejo CA 92656 USA
Within the USA: +1(949) 380-6100
Sales: +1 (949) 380-6136
© 2013 Microsemi Corporation. All rights reserved. Microsemi and the Microsemi logo are trademarks of
Microsemi Corporation. All other trademarks and service marks are the property of their respective owners.
Fax: +1 (949) 215-4996
LX7175-4/1.2
相关型号：
©2020 ICPDF网 联系我们和版权申明