Order
Now
Product
Folder
Support &
Community
Tools &
Software
Technical
Documents
LM2852
SNVS325E – JANUARY 2005 – REVISED JANUARY 2016
LM2852 2A 500/1500 kHz Synchronous Buck Regulator
1 Features
3 Description
•
•
The LM2852 synchronous buck regulator is a high
frequency step-down switching voltage regulator
capable of driving up to a 2A load with excellent line
and load regulation. The LM2852 can accept an input
voltage between 2.85 V and
5.5 V and deliver an output voltage that is factory
programmable from 0.8 V to 3.3 V in 100-mV
increments. The LM2852 is available with a choice of
two switching frequencies –500 kHz (LM2852Y) or
1.5 MHz (LM2852X). It also features internal, typethree compensation to deliver a low component count
solution. The exposed-pad HTSSOP-14 package
enhances the thermal performance of the LM2852.
1
•
•
•
•
•
•
•
Input Voltage Range of 2.85 V to 5.5 V
Factory EEPROM Set Output Voltages from 0.8 V
to 3.3 V in 100-mV Increments
Maximum Load Current of 2 A
Voltage Mode Control
Internal Type-Three Compensation
Switching Frequency of 500 kHz or 1.5 MHz
Low Standby Current of 10 µA
Internal 60-mΩ MOSFET Switches
Standard Voltage Options 0.8/1/1.2/1.5/1.8/2.5/3.3
V
Device Information(1)
2 Applications
•
•
•
•
PART NUMBER
Low Voltage Point of Load Regulation
Local Solution for FPGA/DSP/ASIC Core Power
Broadband Networking and Communications
Infrastructure
Portable Computing
space
Typical Application Circuit
LM2852
PACKAGE
HTSSOP (14)
BODY SIZE (NOM)
5.00 mm × 4.40 mm
(1) For all available packages, see the orderable addendum at
the end of the data sheet.
Figure 1. Efficiency vs ILOAD
VIN = 3.3V
96
PVIN
CIN = 22 PF
AVIN
EN
SS
LM2852Y
SNS
PGND
PVIN = 3.3V
VOUT = 2.5V
ILOAD = 0A to 2A
SW
SGND
LO = 10 PH
+
94
CO = 100 PF
EFFICIENCY (%)
CSS = 2.7 nF
92
90
88
86
84
0.1
1.0
10
ILOAD (A)
1
An IMPORTANT NOTICE at the end of this data sheet addresses availability, warranty, changes, use in safety-critical applications,
intellectual property matters and other important disclaimers. PRODUCTION DATA.
LM2852
SNVS325E – JANUARY 2005 – REVISED JANUARY 2016
www.ti.com
Table of Contents
1
2
3
4
5
6
7
Features ..................................................................
Applications ...........................................................
Description .............................................................
Revision History.....................................................
Pin Configuration and Functions .........................
Specifications.........................................................
1
1
1
2
3
4
6.1
6.2
6.3
6.4
6.5
6.6
6.7
6.8
4
4
4
4
5
7
8
Absolute Maximum Ratings ......................................
ESD Ratings..............................................................
Recommended Operating Conditions.......................
Thermal Information ..................................................
Electrical Characteristics...........................................
LM2852Y Typical Characteristics (500 kHz).............
LM2852X Typical Characteristics (1500 kHz)...........
LM2852 Typical Characteristics (Both Y and X
Versions) ....................................................................
9
Detailed Description ............................................ 10
7.1 Overview ................................................................. 10
7.2 Functional Block Diagram ....................................... 10
7.3 Feature Description................................................. 11
7.4 Device Functional Modes........................................ 11
8
Application and Implementation ........................ 12
8.1 Application Information............................................ 12
8.2 Typical Application ................................................. 12
9 Power Supply Recommendations...................... 18
10 Layout................................................................... 18
10.1 Layout Guidelines ................................................. 18
10.2 Layout Example .................................................... 18
11 Device and Documentation Support ................. 19
11.1
11.2
11.3
11.4
11.5
Device Support......................................................
Community Resources..........................................
Trademarks ...........................................................
Electrostatic Discharge Caution ............................
Glossary ................................................................
19
19
19
19
19
12 Mechanical, Packaging, and Orderable
Information ........................................................... 19
4 Revision History
NOTE: Page numbers for previous revisions may differ from page numbers in the current version.
Changes from Revision D (April 2013) to Revision E
•
2
Page
Added ESD Ratings table, Feature Description section, Device Functional Modes, Application and Implementation
section, Power Supply Recommendations section, Layout section, Device and Documentation Support section, and
Mechanical, Packaging, and Orderable Information section .................................................................................................. 1
Submit Documentation Feedback
Copyright © 2005–2016, Texas Instruments Incorporated
Product Folder Links: LM2852
LM2852
www.ti.com
SNVS325E – JANUARY 2005 – REVISED JANUARY 2016
5 Pin Configuration and Functions
PWP Package
14-Pin HTSSOP
Top View
AVIN
1
14
SNS
EN
2
13
NC
SGND
3
12
NC
SS
4
11
PGND
NC
5
10
PGND
PVIN
6
9
SW
PVIN
7
8
SW
LM2852
Pin Functions
PIN
NAME
NO.
I/O
DESCRIPTION
AVIN
1
I
Chip bias input pin. This provides power to the logic of the chip. Connect to the input voltage
or a separate rail.
EN
2
I
Enable. Connect this pin to ground to disable the chip; connect to AVIN or leave floating to
enable the chip; enable is internally pulled up.
Exposed
NC
Connect to ground.
5, 12, 13
No connect. These pins must be tied to ground or left floating in the application.
PGND
10, 11
G
Power ground. Connect this to an internal ground plane or other large ground plane.
PVIN
6, 7
I
Input supply pin. PVIN is connected to the input voltage. This rail connects to the source of
the internal power PFET.
SGND
3
G
Signal ground.
SNS
14
O
Output voltage sense pin. Connect this pin to the output voltage as close to the load as
possible.
SS
4
I
Soft-start pin. Connect this pin to a small capacitor to control startup. The soft-start
capacitance range is restricted to values 1 nF to 50 nF.
SW
8, 9
O
Switch pin. Connect to the output inductor.
Submit Documentation Feedback
Copyright © 2005–2016, Texas Instruments Incorporated
Product Folder Links: LM2852
3
LM2852
SNVS325E – JANUARY 2005 – REVISED JANUARY 2016
www.ti.com
6 Specifications
6.1 Absolute Maximum Ratings
over operating free-air temperature range (unless otherwise noted) (1) (2)
MIN
PVIN, AVIN, EN, SNS
Power dissipation
V
Infrared (15 sec)
220
°C
Vapor phase (60 sec)
215
°C
150
°C
150
°C
Maximum junction temperature
−65
Storage temperature, Tstg
(2)
UNIT
6.5
Internally limited
14-Pin exposed pad HTSSOP package
(1)
MAX
Stresses beyond those listed under Absolute Maximum Ratings may cause permanent damage to the device. These are stress ratings
only, which do not imply functional operation of the device at these or any other conditions beyond those indicated under Recommended
Operating Conditions. Exposure to absolute-maximum-rated conditions for extended periods may affect device reliability.
If Military/Aerospace specified devices are required, please contact the Texas Instruments Sales Office/ Distributors for availability and
specifications.
6.2 ESD Ratings
V(ESD)
(1)
Electrostatic discharge
VALUE
UNIT
±2000
V
Human-body model (HBM), per ANSI/ESDA/JEDEC JS-001 (1)
JEDEC document JEP155 states that 500-V HBM allows safe manufacturing with a standard ESD control process.
6.3 Recommended Operating Conditions
over operating free-air temperature range (unless otherwise noted)
MIN
MAX
UNIT
PVIN to GND
1.5
5.5
AVIN to GND
2.85
5.5
V
Junction temperature
−40
125
°C
V
6.4 Thermal Information
LM2852
THERMAL METRIC (1)
PWP (HTTSOP)
UNIT
14 PINS
RθJA
Junction-to-ambient thermal resistance
39.2
°C/W
RθJC(top)
Junction-to-case (top) thermal resistance
24.1
°C/W
RθJB
Junction-to-board thermal resistance
20.1
°C/W
ψJT
Junction-to-top characterization parameter
0.6
°C/W
ψJB
Junction-to-board characterization parameter
19.8
°C/W
RθJC(bot)
Junction-to-case (bottom) thermal resistance
1.7
°C/W
(1)
4
For more information about traditional and new thermal metrics, see the Semiconductor and IC Package Thermal Metrics application
report.
Submit Documentation Feedback
Copyright © 2005–2016, Texas Instruments Incorporated
Product Folder Links: LM2852
LM2852
www.ti.com
SNVS325E – JANUARY 2005 – REVISED JANUARY 2016
6.5 Electrical Characteristics
AVIN = PVIN = 5 V unless otherwise indicated under the Test Conditions column. Limits apply over the junction temperature
(TJ) range of –40°C to 125°C (unless otherwise noted). Minimum and Maximum limits are ensured through test, design, or
statistical correlation. Typical values represent the most likely parametric norm at TJ = 25°C, and are provided for reference
purposes only.
PARAMETER
TEST CONDITIONS
MIN
TYP
MAX
UNIT
SYSTEM PARAMETERS
VOUT = 0.8-V option
VOUT = 1-V option
VOUT
ΔVOUT/ ΔAVIN
Voltage
tolerance (1)
Line regulation (1)
VON
Load regulation
0.818
1.0225
VOUT = 1.2-V option
1.173
1.227
VOUT = 1.5-V option
1.4663
1.5337
VOUT = 1.8-V option
1.7595
1.8405
VOUT = 2.5-V option
2.4437
2.5563
VOUT = 3-V option
2.9325
3.0675
VOUT = 3.3-V option
3.2257
3.3743
VOUT = 0.8 V, 1 V, 1.2 V, 1.5 V, TJ = –40°C to
125°C
1.8 V or 2.5 V,
2.85 V ≤ AVIN ≤ 5.5 V
TJ = 25°C
VOUT = 3.3 V,
3.5 V ≤ AVIN ≤ 5.5 V
ΔVOUT/ΔIO
0.782
0.9775
0.6%
0.2%
TJ = –40°C to
125°C
0.6%
TJ = 25°C
0.2%
Normal operation
TJ = 25°C
8
Rising
TJ = –40°C to
125°C
Falling hysteresis
TJ = –40°C to
125°C
PFET ON resistance
85
NFET ON resistance
140
120
TJ = 25°C
RSS
Soft-start resistance
400
LM2852X
TJ = –40°C to
125°C
LM2852Y
TJ = 25°C
IQ
Operating current
Non-switching
RSNS
(1)
Shutdown quiescent
current
EN = 0 V
Sense pin resistance
TJ = 25°C
4
2.25
A
3.65
3
2
mA
0.85
TJ = –40°C to
125°C
TJ = 25°C
kΩ
4.95
TJ = –40°C to
125°C
TJ = 25°C
ISD
2.75
TJ = 25°C
Peak current limit
threshold
ICL
mΩ
55
TJ = 25°C
TJ = –40°C to
125°C
mΩ
75
TJ = –40°C to
125°C
Isw = 2 A
mV
150
TJ = 25°C
rDSON-N
210
TJ = –40°C to
125°C
Isw = 2 A
V
2.47
TJ = 25°C
rDSON-P
mV/A
2.85
TJ = 25°C
UVLO threshold (AVIN)
V
25
µA
10
400
kΩ
VOUT measured in a non-switching, closed-loop configuration at the SNS pin.
Submit Documentation Feedback
Copyright © 2005–2016, Texas Instruments Incorporated
Product Folder Links: LM2852
5
LM2852
SNVS325E – JANUARY 2005 – REVISED JANUARY 2016
www.ti.com
Electrical Characteristics (continued)
AVIN = PVIN = 5 V unless otherwise indicated under the Test Conditions column. Limits apply over the junction temperature
(TJ) range of –40°C to 125°C (unless otherwise noted). Minimum and Maximum limits are ensured through test, design, or
statistical correlation. Typical values represent the most likely parametric norm at TJ = 25°C, and are provided for reference
purposes only.
PARAMETER
TEST CONDITIONS
MIN
TYP
MAX
UNIT
PWM
LM2852X
1500-kHz option.
TJ = –40°C to
125°C
1050
TJ = 25°C
fosc
LM2852Y
500-kHz option.
TJ = –40°C to
125°C
Duty cycle
kHz
1500
325
TJ = 25°C
Drange
1825
625
kHz
500
0%
100%
ENABLE CONTROL (2)
VIH
EN pin minimum high
input
VIL
EN pin maximum low
input
IEN
EN pin pullup current
% of
AVIN
75
25
EN = 0 V
TJ = 25°C
% of
AVIN
1.2
µA
THERMAL CONTROLS
TSD
TJ for thermal shutdown
TJ = 25°C
165
°C
TSD-HYS
Hysteresis for thermal
shutdown
TJ = 25°C
10
°C
(2)
6
The enable pin is internally pulled up, so the LM2852 is automatically enabled unless an external enable voltage is applied.
Submit Documentation Feedback
Copyright © 2005–2016, Texas Instruments Incorporated
Product Folder Links: LM2852
LM2852
www.ti.com
SNVS325E – JANUARY 2005 – REVISED JANUARY 2016
6.6 LM2852Y Typical Characteristics (500 kHz)
92
96
PVIN = 3.3V
PVIN = 3.3V
90
94
86
84
92
EFFICIENCY (%)
EFFICIENCY (%)
88
PVIN = 5.0V
82
90
PVIN = 5.0V
88
80
86
78
76
0.1
1.0
84
10
0.1
1.0
Figure 3. Efficiency vs ILoad VOUT = 2.5 V
Figure 2. Efficiency vs ILoad VOUT = 1.5 V
95
560
94
550
VIN = 3.3V
PVIN = 5.0V
540
FREQUENCY (kHz)
EFFICIENCY (%)
93
92
91
90
530
520
510
89
500
88
490
87
0.1
10
ILOAD (A)
ILOAD (A)
1.0
10
VIN = 5V
480
-50
-25
0
25
50
75
100 125 150
TEMPERATURE (oC)
ILOAD (A)
Figure 4. Efficiency vs ILoad VOUT = 3.3 V
Figure 5. Frequency vs Temperature
Submit Documentation Feedback
Copyright © 2005–2016, Texas Instruments Incorporated
Product Folder Links: LM2852
7
LM2852
SNVS325E – JANUARY 2005 – REVISED JANUARY 2016
www.ti.com
6.7 LM2852X Typical Characteristics (1500 kHz)
100
85
PVIN = 3.3V
PVIN = 3.3V
80
90
70
65
60
80
EFFICIENCY (%)
EFFICIENCY (%)
75
PVIN = 5.0V
PVIN = 5.0V
70
60
55
50
50
45
0.1
1.0
40
0.1
10
1.0
ILOAD (A)
ILOAD (A)
Figure 6. Efficiency vs ILoad VOUT = 1.5 V
Figure 7. Efficiency vs ILoad VOUT = 2.5 V
90
1600
85
1550
FREQUENCY (kHz)
EFFICIENCY (%)
80
75
PVIN = 5.0V
70
65
60
55
50
0.1
PVIN = 3.3V
1500
1450
PVIN = 5.0V
1400
1350
1300
1250
1.0
10
1200
-50 -25
ILOAD (A)
0
25
50
75
80
85
90
o
TEMPERATURE ( C)
Figure 8. Efficiency vs ILoad VOUT = 3.3 V
8
10
Submit Documentation Feedback
Figure 9. Frequency vs Temperature
Copyright © 2005–2016, Texas Instruments Incorporated
Product Folder Links: LM2852
LM2852
www.ti.com
SNVS325E – JANUARY 2005 – REVISED JANUARY 2016
6.8 LM2852 Typical Characteristics (Both Y and X Versions)
100
130
120
90
PFET RDSON (m:)
NFET RDSON (m:)
110
80
PVIN = 3.3V
70
PVIN = 5.0V
60
PVIN = 3.3V
100
90
PVIN = 5.0V
80
70
50
60
40
-50
-25
0
25
50
75
50
-50
100 125 150
-25
0
25
50
75
100 125 150
TEMPERATURE (oC)
TEMPERATURE (oC)
Figure 10. NMOS Switch RDSON vs Temperature
Figure 11. PMOS Switch RDSON vs Temperature
Submit Documentation Feedback
Copyright © 2005–2016, Texas Instruments Incorporated
Product Folder Links: LM2852
9
LM2852
SNVS325E – JANUARY 2005 – REVISED JANUARY 2016
www.ti.com
7 Detailed Description
7.1 Overview
The LM2852 is a DC-DC synchronous buck regulator. Integration of the PWM controller, power switches and
compensation network greatly reduces the component count required to implement a switching power supply.
7.2 Functional Block Diagram
SGND
PVIN
Reference
Oscillator
UVLO
DAC
AVIN
Current Limit
Ramp and Clock
Generator
400 k:
EN
Gate
Drive
Error
Amp
SS
+
20 pF
200 k:
200 k:
Zc1
Zc2
SW
+
PWM
Comp
PGND
SNS
10
Submit Documentation Feedback
Copyright © 2005–2016, Texas Instruments Incorporated
Product Folder Links: LM2852
LM2852
www.ti.com
SNVS325E – JANUARY 2005 – REVISED JANUARY 2016
7.3 Feature Description
7.3.1 Split-Rail Operation
The LM2852 can be powered using two separate voltages for AVIN and PVIN. AVIN is the supply for the control
logic; PVIN is the supply for the power FETs. The output filter components need to be chosen based on the
value of PVIN. For PVIN levels lower than 3.3 V, use output filter component values recommended for 3.3 V.
PVIN must always be equal to or less than AVIN.
PVIN = 3.3V
AVIN = 5V
PVIN
AVIN
EN
SS
CIN = 47 PF
1 PF
LM2852Y
SNS
VOUT = 1.5V
ILOAD = 0A to 2A
SW
SGND
PGND
LO = 10 PH
+
CO = 100 PF
CSS = 3.3 nF
Figure 12. Split-Rail Operation
7.3.2 Switch Node Protection
The LM2852 includes protection circuitry that monitors the voltage on the switch pin. Under certain conditions,
switching is disabled in order to protect the switching devices. One result of the protection circuitry may be
observed when power to the LM2852 is applied with no or light load on the output. The output regulates to the
rated voltage, but no switching may be observed. As soon as the output is loaded, the LM2852 begins normal
switching operation.
7.4 Device Functional Modes
The LM2852 Enable pin is internally pulled up so that the part is enabled anytime the input voltage exceeds the
UVLO threshold. A pulldown resistor can be used to set the enable input to low.
Submit Documentation Feedback
Copyright © 2005–2016, Texas Instruments Incorporated
Product Folder Links: LM2852
11
LM2852
SNVS325E – JANUARY 2005 – REVISED JANUARY 2016
www.ti.com
8 Application and Implementation
NOTE
Information in the following applications sections is not part of the TI component
specification, and TI does not warrant its accuracy or completeness. TI’s customers are
responsible for determining suitability of components for their purposes. Customers must
validate and test their design implementation to confirm system functionality.
8.1 Application Information
The LM2852 is a DC-DC synchronous buck regulator capable of driving a maximum load current of 2A, with an
input range of 2.85 V to 5.5 V and a variable output range of 0.8 V to 3.3 V. Figure 13 is a schematic example of
a typical application.
8.2 Typical Application
VIN = 3.3V
U1
PVIN
Rf
CINX
AVIN
EN
Cf
CIN
SS
LM2852
SNS
VOUT = 1.8V
ILOAD = 0A to 2A
SW
SGND
PGND
LO
+
CO
CSS
Figure 13. LM2852 Example Circuit Schematic
8.2.1 Design Requirements
A typical application requires only four components: an input capacitor, a soft-start capacitor, an output filter
capacitor and an output filter inductor. To properly size the components for the application, the designer needs
the following parameters: input voltage range, output voltage, output current range, and required switching
frequency. These four main parameters affect the choices of component available to achieve a proper system
behavior.
8.2.2 Detailed Design Procedure
8.2.2.1 Input Capacitor (CIN)
Fast switching of large currents in the buck converter places a heavy demand on the voltage source supplying
PVIN. The input capacitor, CIN, supplies extra charge when the switcher needs to draw a burst of current from
the supply. The RMS current rating and the voltage rating of the CIN capacitor are therefore important in the
selection of CIN. The RMS current specification can be approximated by Equation 1:
IRMS = ILOAD
D(1-D)
where
•
D is the duty cycle, VOUT/VIN. CIN also provides filtering of the supply.
(1)
Trace resistance and inductance degrade the benefits of the input capacitor, so CIN must be placed very close to
PVIN in the layout. A 22-µF or 47-µF ceramic capacitor is typically sufficient for CIN. In parallel with the large
input capacitance a smaller capacitor may be added such as a 1-µF ceramic for higher frequency filtering.
12
Submit Documentation Feedback
Copyright © 2005–2016, Texas Instruments Incorporated
Product Folder Links: LM2852
LM2852
www.ti.com
SNVS325E – JANUARY 2005 – REVISED JANUARY 2016
Typical Application (continued)
8.2.2.2 Soft-Start Capacitor (CSS)
The DAC that sets the reference voltage of the error amp sources a current through a resistor to set the
reference voltage. The reference voltage is one half of the output voltage of the switcher due to the 200 kΩ
divider connected to the SNS pin. Upon start-up, the output voltage of the switcher tracks the reference voltage
with a two to one ratio as the DAC current charges the capacitance connected to the reference voltage node.
Internal capacitance of 20 pF is permanently attached to the reference voltage node which is also connected to
the soft-start pin, SS. Adding a soft-start capacitor externally increases the time it takes for the output voltage to
reach its final level.
The charging time required for the reference voltage can be estimated using the RC time constant of the DAC
resistor and the capacitance connected to the SS pin. Three RC time constant periods are needed for the
reference voltage to reach 95% of its final value. The actual start-up time varies with differences in the DAC
resistance and higher-order effects.
If little or no soft-start capacitance is connected, then the start-up time may be determined by the time required
for the current limit current to charge the output filter capacitance. The capacitor charging equation I = C ΔV/Δt
can be used to estimate the start-up time in this case. For example, a part with a 3-V output, a 100-µF output
capacitance and a 3-A current limit threshold would require a time of 100 µs, seen in Equation 2:
't = C
'V
3V
= 100 PF
= 100 Ps
I
3A
(2)
Since it is undesirable for the power supply to start up in current limit, a soft-start capacitor must be chosen to
force the LM2852 to start up in a more controlled fashion based on the charging of the soft-start capacitance. In
this example, suppose a 3 ms start time is desired. Three time constants are required for charging the soft-start
capacitor to 95% of the final reference voltage. So in this case RC = 1 ms. The DAC resistor, R, is 400 kΩ so C
can be calculated to be 2.5 nF. A 2.7-nF ceramic capacitor can be chosen to yield approximately a 3 ms start-up
time.
8.2.2.3 Soft-Start Capacitor (CSS) and Fault Conditions
Various fault conditions such as short circuit and UVLO of the LM2852 activate internal circuitry designed to
control the voltage on the soft-start capacitor. For example, during a short circuit current limit event, the output
voltage typically falls to a low voltage. During this time, the soft-start voltage is forced to track the output so that
once the short is removed, the LM2852 can restart gracefully from whatever voltage the output reached during
the short circuit event. The range of soft-start capacitors is therefore restricted to values 1 nF to 50 nF.
8.2.2.4 Compensation
The LM2852 provides a highly integrated solution to power supply design. The compensation of the LM2852,
which is type-three, is included on-chip. The benefit to integrated compensation is straightforward, simple power
supply design. Since the output filter capacitor and inductor values impact the compensation of the control loop,
the range of L, C and CESR values is restricted in order to ensure stability.
Submit Documentation Feedback
Copyright © 2005–2016, Texas Instruments Incorporated
Product Folder Links: LM2852
13
LM2852
SNVS325E – JANUARY 2005 – REVISED JANUARY 2016
www.ti.com
Typical Application (continued)
8.2.2.5 Output Filter Values
Table 1 details the recommended inductor and capacitor ranges for the LM2852 that are suggested for various
typical output voltages. Values slightly different than those recommended may be used, however the phase
margin of the power supply may be degraded.
Table 1. Output Filter Values
FREQUENCY
OPTION
LM2852Y
(500 kHz)
LM2852X
(1500 kHz)
14
VOUT (V)
PVIN (V)
0.8
L (µH)
C (µF)
CESR (mΩ)
MIN
MAX
MIN
MAX
MIN
MAX
3.3
10
15
100
220
70
200
0.8
5
10
15
100
120
70
200
1
3.3
10
15
100
180
70
200
1
5
10
15
100
180
70
200
1.2
3.3
10
15
100
180
70
200
1.2
5
15
22
100
120
70
200
1.5
3.3
10
15
100
120
70
200
1.5
5
22
22
100
120
70
200
1.8
3.3
10
15
100
120
100
200
1.8
5
22
33
100
120
100
200
2.5
3.3
6.8
10
68
120
95
275
2.5
5
15
22
68
120
95
275
3.3
5
15
22
68
100
100
275
0.8
3.3
0.8
5
1
3.3
1
5
1.2
3.3
1.2
5
1.5
3.3
1.5
5
1.8
3.3
1.8
5
2.5
3.3
2.5
5
3.3
5
1
Submit Documentation Feedback
10
The 1500-kHz version is
designed for ceramic output
capacitors, which typically have
very low ESR (< 10 mΩ.)
Copyright © 2005–2016, Texas Instruments Incorporated
Product Folder Links: LM2852
LM2852
www.ti.com
SNVS325E – JANUARY 2005 – REVISED JANUARY 2016
8.2.2.6 Choosing an Inductance Value
The current ripple present in the output filter inductor is determined by the input voltage, output voltage, switching
frequency and inductance according to Equation 3:
'IL =
D x (VIN - VOUT)
fxL
where
•
•
•
•
•
•
ΔIL is the peak-to-peak current ripple.
D is the duty cycle VOUT/VIN.
VIN is the input voltage applied to the PVIN pin.
VOUT is the output voltage of the switcher.
f is the switching frequency.
L is the inductance of the output filter inductor.
(3)
Knowing the current ripple is important for inductor selection since the peak current through the inductor is the
load current plus one half the ripple current. Care must be taken to ensure the peak inductor current does not
reach a level high enough to trip the current limit circuitry of the LM2852.
As an example, consider a 5-V to 1.2-V conversion and a 500-kHz switching frequency. According to Table 1, a
15-µH inductor may be used. Calculating the expected peak-to-peak ripple, as seen in Equation 4.
'IL =
1.2V
x (5V - 1.2V)
5V
500 kHz x 15 PH
= 121.6 mA
(4)
The maximum inductor current for a 2-A load would therefore be 2 A plus 60.8 mA, 2.0608 A. As shown in the
ripple equation, the current ripple is inversely proportional to inductance.
8.2.2.7 Output Filter Inductors
Once the inductance value is chosen, the key parameter for selecting the output filter inductor is its saturation
current (Isat) specification. Typically Isat is given by the manufacturer as the current at which the inductance of the
coil falls to a certain percentage of the nominal inductance. The Isat of an inductor used in an application must be
greater than the maximum expected inductor current to avoid saturation. Table 2 lists the inductors that may be
suitable in LM2852 applications.
Table 2. LM2852 Output Filter Inductors
INDUCTANCE (µH)
PART NUMBER
VENDOR
1
DO1608C-102
Coilcraft
1
DO1813P-102HC
Coilcraft
6.8
DO3316P-682
Coilcraft
7
MSS1038-702NBC
Coilcraft
10
DO3316P-103
Coilcraft
10
MSS1038-103NBC
Coilcraft
12
MSS1038-123NBC
Coilcraft
15
D03316P-153
Coilcraft
15
MSS1038-153NBC
Coilcraft
18
MSS1038-183NBC
Coilcraft
22
DO3316P-223
Coilcraft
22
MSS1038-223NBC
Coilcraft
22
DO3340P-223
Coilcraft
27
MSS1038-273NBC
Coilcraft
33
MSS1038-333NBC
Coilcraft
33
DO3340P-333
Coilcraft
Submit Documentation Feedback
Copyright © 2005–2016, Texas Instruments Incorporated
Product Folder Links: LM2852
15
LM2852
SNVS325E – JANUARY 2005 – REVISED JANUARY 2016
www.ti.com
8.2.2.8 Output Filter Capacitors
The capacitors that may be used in the output filter with the LM2852 are limited in value and ESR range
according to Table 1. Table 3 lists some examples of capacitors that can typically be used in an LM2852
application.
Table 3. LM2852 Output Filter Capacitors
CAPACITANCE (µF)
PART NUMBER
CHEMISTRY
VENDOR
10
GRM31MR61A106KE19
Ceramic
Murata
10
GRM32DR61E106K
Ceramic
Murata
68
595D686X_010C2T
Tantalum
Vishay - Sprague
68
595D686X_016D2T
Tantalum
Vishay - Sprague
100
595D107X_6R3C2T
Tantalum
Vishay - Sprague
100
595D107X_016D2T
Tantalum
Vishay - Sprague
100
NOSC107M004R0150
Niobium Oxide
AVX
100
NOSD107M006R0100
Niobium Oxide
AVX
120
595D127X_004C2T
Tantalum
Vishay - Sprague
120
595D127X_010D2T
Tantalum
Vishay - Sprague
150
595D157X_004C2T
Tantalum
Vishay - Sprague
150
595D157X_016D2T
Tantalum
Vishay - Sprague
150
NOSC157M004R0150
Niobium Oxide
AVX
150
NOSD157M006R0100
Niobium Oxide
AVX
220
595D227X_004D2T
Tantalum
Vishay - Sprague
220
NOSD227M004R0100
Niobium Oxide
AVX
220
NOSE227M006R0100
Niobium Oxide
AVX
Table 4. Bill of Materials for 500kHz (LM2852Y) 3.3 VIN to 1.8 VOUT Conversion
ID
PART NUMBER
TYPE
SIZE
HTSSOP-14
U1
LM2852YMXA-1.8
2-A buck
LO
DO3316P-153
Inductor
CO*
595D107X_6R3C2T
Capacitor
PARAMETERS
QTY
VENDOR
1
TI
15 µH
1
Coilcraft
Case Code “C”
100 µF ±20%
1
Vishay-Sprague
Murata
CIN
GRM32ER60J476ME20B
Capacitor
1210
47 µF/X5R/6.3V
1
CINX
GRM21BR71C105KA01B
Capacitor
0805
1 µF/X7R/16V
1
Murata
CSS
VJ0805Y272KXXA
Capacitor
0805
2.7 nF ±10%
1
Vishay-Vitramon
Rf
CRCW060310R0F
Resistor
0603
10 Ω ±10%
1
Vishay-Dale
Cf
GRM21BR71C105KA01B
Capacitor
0805
1 µF/X7R/16V
1
Murata
Table 5. Bill of Materials for 1500-kHz (LM2852X) 3.3-V to 1.8-V Conversion
ID
16
PART NUMBER
U1
LM2852XMXA-1.8
TYPE
SIZE
2-A buck
HTSSOP-14
Inductor
PARAMETERS
QTY
VENDOR
1
TI
L0
DO1813P-102HC
1 µH
1
Coilcraft
C0
GRM32DR61E106K
Capacitor
1210
10 µF/X5R/25V
1
Murata
CIN
GRM32ER60J476ME20B
Capacitor
1210
47 µF/X5R/6.3V
1
Murata
CINX
GRM21BR71C105KA01B
Capacitor
0805
1 µF/X7R/16V
1
Murata
CSS
VJ0805Y272KXXA
Capacitor
0805
2.7 nF ±10%
1
Vishay-Vitramon
Rf
CRCW060310R0F
Resistor
0603
10 Ω ±10%
1
Vishay-Dale
Cf
GRM21BR71C105KA01B
Capacitor
0805
1 µF/X7R/16V
1
Murata
Submit Documentation Feedback
Copyright © 2005–2016, Texas Instruments Incorporated
Product Folder Links: LM2852
LM2852
www.ti.com
SNVS325E – JANUARY 2005 – REVISED JANUARY 2016
8.2.3 Application Curves
1100
17
1000
15
125oC
900
13
o
85 C
IQ (PA)
IQ SHUTDOWN (PA)
125oC
11
o
800
85oC
25 C
25oC
700
9
-40oC
7
5
2.5
3
3.5
4
4.5
-40oC
600
5
5.5
500
2.5
3
3.5
4
4.5
5
5.5
VIN (V)
VIN (V)
Figure 14. Shutdown Current vs VIN
Figure 15. Quiescent Current (Non-Switching) vs VIN
Submit Documentation Feedback
Copyright © 2005–2016, Texas Instruments Incorporated
Product Folder Links: LM2852
17
LM2852
SNVS325E – JANUARY 2005 – REVISED JANUARY 2016
www.ti.com
9 Power Supply Recommendations
The LM2852 is designed to operate from various DC power supplies. If so, VIN input must be protected from
reversal voltage and voltage dump over 6.5 V. The impedance of the input supply rail must be low enough that
the input current transient does not cause drop below VIN UVLO level. If the input supply is connected by using
long wires, additional bulk capacitance may be required in addition to normal input capacitor.
10 Layout
10.1 Layout Guidelines
These are several guidelines to follow while designing the PCB layout for an LM2852 application.
• The input bulk capacitor, CIN, must be placed very close to the PVIN pin to keep the resistance as low as
possible between the capacitor and the pin. High-current levels are present in this connection
• All ground connections must be tied together. Use a broad ground plane, for example a completely filled back
plane, to establish the lowest resistance possible between all ground connections
• The sense pin connection must be made as close to the load as possible so that the voltage at the load is the
expected regulated value. The sense line must not run too close to nodes with high EMI (such as the switch
node) to minimize interference
• The switch node connections must be low resistance to reduce power losses. Low resistance means the
trace between the switch pin and the inductor must be wide. However, the area of the switch node must not
be too large since EMI increases with greater area. So connect the inductor to the switch pin with a short, but
wide trace. Other high current connections in the application such as PVIN and VOUT assume the same trade
off between low resistance and EMI
• Allow area under the chip to solder the entire exposed die attach pad to ground for improved thermal and
electrical performance
10.2 Layout Example
Figure 16. PCB Layout Example
18
Submit Documentation Feedback
Copyright © 2005–2016, Texas Instruments Incorporated
Product Folder Links: LM2852
LM2852
www.ti.com
SNVS325E – JANUARY 2005 – REVISED JANUARY 2016
11 Device and Documentation Support
11.1 Device Support
11.1.1 Third-Party Products Disclaimer
TI'S PUBLICATION OF INFORMATION REGARDING THIRD-PARTY PRODUCTS OR SERVICES DOES NOT
CONSTITUTE AN ENDORSEMENT REGARDING THE SUITABILITY OF SUCH PRODUCTS OR SERVICES
OR A WARRANTY, REPRESENTATION OR ENDORSEMENT OF SUCH PRODUCTS OR SERVICES, EITHER
ALONE OR IN COMBINATION WITH ANY TI PRODUCT OR SERVICE.
11.2 Community Resources
The following links connect to TI community resources. Linked contents are provided "AS IS" by the respective
contributors. They do not constitute TI specifications and do not necessarily reflect TI's views; see TI's Terms of
Use.
TI E2E™ Online Community TI's Engineer-to-Engineer (E2E) Community. Created to foster collaboration
among engineers. At e2e.ti.com, you can ask questions, share knowledge, explore ideas and help
solve problems with fellow engineers.
Design Support TI's Design Support Quickly find helpful E2E forums along with design support tools and
contact information for technical support.
11.3 Trademarks
E2E is a trademark of Texas Instruments.
All other trademarks are the property of their respective owners.
11.4 Electrostatic Discharge Caution
These devices have limited built-in ESD protection. The leads should be shorted together or the device placed in conductive foam
during storage or handling to prevent electrostatic damage to the MOS gates.
11.5 Glossary
SLYZ022 — TI Glossary.
This glossary lists and explains terms, acronyms, and definitions.
12 Mechanical, Packaging, and Orderable Information
The following pages include mechanical, packaging, and orderable information. This information is the most
current data available for the designated devices. This data is subject to change without notice and revision of
this document. For browser-based versions of this data sheet, refer to the left-hand navigation.
Submit Documentation Feedback
Copyright © 2005–2016, Texas Instruments Incorporated
Product Folder Links: LM2852
19
PACKAGE OPTION ADDENDUM
www.ti.com
30-Sep-2021
PACKAGING INFORMATION
Orderable Device
Status
(1)
Package Type Package Pins Package
Drawing
Qty
Eco Plan
(2)
Lead finish/
Ball material
MSL Peak Temp
Op Temp (°C)
Device Marking
(3)
(4/5)
(6)
LM2852XMXA-1.0/NOPB
ACTIVE
HTSSOP
PWP
14
94
RoHS & Green
SN
Level-1-260C-UNLIM
-40 to 125
2852X
1.0
LM2852XMXA-1.2/NOPB
ACTIVE
HTSSOP
PWP
14
94
RoHS & Green
SN
Level-1-260C-UNLIM
-40 to 125
2852X
1.2
LM2852XMXA-1.5/NOPB
ACTIVE
HTSSOP
PWP
14
94
RoHS & Green
SN
Level-1-260C-UNLIM
-40 to 125
2852X
1.5
LM2852XMXA-1.8/NOPB
ACTIVE
HTSSOP
PWP
14
94
RoHS & Green
SN
Level-1-260C-UNLIM
-40 to 125
2852X
1.8
LM2852XMXA-2.5/NOPB
ACTIVE
HTSSOP
PWP
14
94
RoHS & Green
SN
Level-1-260C-UNLIM
-40 to 125
2852X
2.5
LM2852XMXA-3.0/NOPB
ACTIVE
HTSSOP
PWP
14
94
RoHS & Green
SN
Level-1-260C-UNLIM
LM2852XMXA-3.3/NOPB
ACTIVE
HTSSOP
PWP
14
94
RoHS & Green
SN
Level-1-260C-UNLIM
-40 to 125
2852X
3.3
LM2852XMXAX-1.2/NOPB
ACTIVE
HTSSOP
PWP
14
2500
RoHS & Green
SN
Level-1-260C-UNLIM
-40 to 125
2852X
1.2
LM2852XMXAX-1.5/NOPB
ACTIVE
HTSSOP
PWP
14
2500
RoHS & Green
SN
Level-1-260C-UNLIM
-40 to 125
2852X
1.5
LM2852XMXAX-1.8/NOPB
ACTIVE
HTSSOP
PWP
14
2500
RoHS & Green
SN
Level-1-260C-UNLIM
-40 to 125
2852X
1.8
LM2852XMXAX-2.5/NOPB
ACTIVE
HTSSOP
PWP
14
2500
RoHS & Green
SN
Level-1-260C-UNLIM
-40 to 125
2852X
2.5
LM2852XMXAX-3.3/NOPB
ACTIVE
HTSSOP
PWP
14
2500
RoHS & Green
SN
Level-1-260C-UNLIM
-40 to 125
2852X
3.3
LM2852YMXA-1.0/NOPB
ACTIVE
HTSSOP
PWP
14
94
RoHS & Green
SN
Level-1-260C-UNLIM
-40 to 125
2852Y
-1.0
LM2852YMXA-1.2/NOPB
ACTIVE
HTSSOP
PWP
14
94
RoHS & Green
SN
Level-1-260C-UNLIM
-40 to 125
2852Y
-1.2
LM2852YMXA-1.3/NOPB
ACTIVE
HTSSOP
PWP
14
94
RoHS & Green
SN
Level-1-260C-UNLIM
LM2852YMXA-1.5/NOPB
ACTIVE
HTSSOP
PWP
14
94
RoHS & Green
SN
Level-1-260C-UNLIM
-40 to 125
2852Y
-1.5
LM2852YMXA-1.8/NOPB
ACTIVE
HTSSOP
PWP
14
94
RoHS & Green
SN
Level-1-260C-UNLIM
-40 to 125
2852Y
Addendum-Page 1
2852X
3.0
2852Y
1.3
Samples
PACKAGE OPTION ADDENDUM
www.ti.com
Orderable Device
30-Sep-2021
Status
(1)
Package Type Package Pins Package
Drawing
Qty
Eco Plan
(2)
Lead finish/
Ball material
MSL Peak Temp
Op Temp (°C)
Device Marking
(3)
(4/5)
(6)
-1.8
LM2852YMXA-2.5/NOPB
ACTIVE
HTSSOP
PWP
14
94
RoHS & Green
SN
Level-1-260C-UNLIM
-40 to 125
2852Y
-2.5
LM2852YMXA-3.3
NRND
HTSSOP
PWP
14
94
Non-RoHS
& Green
Call TI
Level-1-260C-UNLIM
-40 to 125
2852Y
-3.3
LM2852YMXA-3.3/NOPB
ACTIVE
HTSSOP
PWP
14
94
RoHS & Green
SN
Level-1-260C-UNLIM
-40 to 125
2852Y
-3.3
LM2852YMXAX-1.0/NOPB
ACTIVE
HTSSOP
PWP
14
2500
RoHS & Green
SN
Level-1-260C-UNLIM
-40 to 125
2852Y
-1.0
LM2852YMXAX-1.2/NOPB
ACTIVE
HTSSOP
PWP
14
2500
RoHS & Green
SN
Level-1-260C-UNLIM
-40 to 125
2852Y
-1.2
LM2852YMXAX-1.5/NOPB
ACTIVE
HTSSOP
PWP
14
2500
RoHS & Green
SN
Level-1-260C-UNLIM
-40 to 125
2852Y
-1.5
LM2852YMXAX-1.8/NOPB
ACTIVE
HTSSOP
PWP
14
2500
RoHS & Green
SN
Level-1-260C-UNLIM
-40 to 125
2852Y
-1.8
LM2852YMXAX-2.5/NOPB
ACTIVE
HTSSOP
PWP
14
2500
RoHS & Green
SN
Level-1-260C-UNLIM
-40 to 125
2852Y
-2.5
LM2852YMXAX-3.3/NOPB
ACTIVE
HTSSOP
PWP
14
2500
RoHS & Green
SN
Level-1-260C-UNLIM
-40 to 125
2852Y
-3.3
(1)
The marketing status values are defined as follows:
ACTIVE: Product device recommended for new designs.
LIFEBUY: TI has announced that the device will be discontinued, and a lifetime-buy period is in effect.
NRND: Not recommended for new designs. Device is in production to support existing customers, but TI does not recommend using this part in a new design.
PREVIEW: Device has been announced but is not in production. Samples may or may not be available.
OBSOLETE: TI has discontinued the production of the device.
(2)
RoHS: TI defines "RoHS" to mean semiconductor products that are compliant with the current EU RoHS requirements for all 10 RoHS substances, including the requirement that RoHS substance
do not exceed 0.1% by weight in homogeneous materials. Where designed to be soldered at high temperatures, "RoHS" products are suitable for use in specified lead-free processes. TI may
reference these types of products as "Pb-Free".
RoHS Exempt: TI defines "RoHS Exempt" to mean products that contain lead but are compliant with EU RoHS pursuant to a specific EU RoHS exemption.
Green: TI defines "Green" to mean the content of Chlorine (Cl) and Bromine (Br) based flame retardants meet JS709B low halogen requirements of
工商网监
湘ICP备2023018690号
