Texas Instruments LM5160A User manual

LM5160A, LM5160 Buck EVM User's Guide
User's Guide
Literature Number: SNVU441B
October 2014–Revised April 2015

Contents
1 Introduction......................................................................................................................... 4
2 Background......................................................................................................................... 4
3 Setup.................................................................................................................................. 4
3.1 Input/Output Connector Description ................................................................................... 4
3.2 Operation.................................................................................................................. 4
3.3 FPWM Mode Selection.................................................................................................. 5
4 Board Layout....................................................................................................................... 5
5 Schematic........................................................................................................................... 6
6 LM5160DNTBKEVM Bill of Materials for 300 kHz Configuration ................................................. 7
7 Performance Curves with LM5160A, LM5160........................................................................... 7
Revision History.......................................................................................................................... 10
2Table of Contents SNVU441B–October 2014–Revised April 2015
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List of Figures
1 EVM Component View with LM5160A ................................................................................... 5
2 EVM Top Copper View with LM5160A ................................................................................... 5
3 EVM Bottom Copper View with LM5160A ............................................................................... 5
4 EVM Top Solder Mask with LM5160A ................................................................................... 5
5 Buck EVM Schematic with LM5160....................................................................................... 6
6 Load Regulation.............................................................................................................. 7
7 Efficiency vs. IOUT............................................................................................................. 7
8 Efficiency vs. VIN ............................................................................................................. 7
9 Efficiency DCM vs. CCM at 300kHz....................................................................................... 7
10 VIN = 48V and FPWM = 0 at no load ..................................................................................... 7
11 VIN = 48V and FPWM = 0 at no load (Zoomed) ......................................................................... 7
12 VIN = 48V and FPWM = 1 at no load ..................................................................................... 8
13 Load Transient (IO= 300mA to 1.5A)...................................................................................... 8
14 Startup at RLOAD = 3Ω........................................................................................................ 8
15 Pre-Bias Startup at RLOAD = 3Ωand VIN = 48V ........................................................................... 8
16 EN/UVLO Startup at RLOAD = 5Ωand VIN = 24V.......................................................................... 8
17 EN/UVLO Startup at RLOAD = 100Ωand VIN = 24V....................................................................... 8
18 Output Short-Circuit at VIN = 48V .......................................................................................... 9
List of Tables
1 Board Specification.......................................................................................................... 4
2 FPWM Pin Mode............................................................................................................. 5
3
SNVU441B–October 2014–Revised April 2015 List of Figures
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User's Guide
SNVU441B–October 2014–Revised April 2015
LM5160A, LM5160 User’s Guide
1 Introduction
The Texas Instruments LM5160DNTBKEVM evaluation module (EVM) helps designers evaluate the
operation and performance of the LM5160A / LM5160 synchronous buck regulator IC in a synchronous
Buck configuration. It also includes the specification for the board, complete application schematic, bill of
materials (BOM), setup instructions, and typical performance curves.
2 Background
The LM5160DNTBKEVM evaluation board provides a fully functional buck regulator, employing the
constant on-time (COT) operating principle. This evaluation board provides a 5-V output over an input
voltage range of 10 V to 60 V. The circuit delivers load current up to 1.5 A. The application schematic is
setup up to operate from a 24 V nominal bus. The nominal switching frequency is approximately 300 kHz.
The LM5160 device name is used generically throughout this document and represents both the LM5160
and LM5160A unless stated otherwise. The only difference between the two is the ability to connect an
external voltage source to the VCC pin of the LM5160A. The board is designed to demonstrate a small
buck solution size for low power wide VIN applications.
Table 1. Board Specification
EVM INPUT VOUT IOUT
LM5160DNTBKEVM VIN=10V–60V 5V 0–1.5A
3 Setup
This section describes the connectors, the test points and the jumper on the EVM as well as how to
properly connect and use the LM5160DNTBKEVM with the LM5160, unless stated otherwise.
3.1 Input/Output Connector Description
J1 – Input is the power input terminal for the converter. The terminal block provides an input VIN (+) and
ground (-) connection to allow the user to attach the EVM to a power supply.
J2 – Output is the regulated output voltage for the converter. The terminal block provides a VOUT (+) and
ground (-) connection to allow the user to attach the EVM to a load.
TP1 – (EN) allows the user to remotely shutdown/startup LM5160 while operating in the buck mode. EN
circuitry is not populated on EVM.
TP2 – (SW) allows the user to connect a scope probe to observe the switch node of the converter.
JP1 –Mode pin allows the user to select between the forced CCM and the DCM operation.
3.2 Operation
For proper operation of the LM5160 Buck converter, the input voltage applied across J1 should be
gradually increased. The load on the output (J2) should not exceed 1.5 A. The inductor L1 utilized in this
board is optimized for small solution size. The saturation current rating (ISAT) of the inductor should be
higher than the LM5160 integrated high side FET peak current-limit threshold of 2.875 A (max.).
The nominal switching frequency can be set using the RON (R3 in the EVM) resistor as shown by
Equation 1:
4LM5160A, LM5160 User’s Guide SNVU441B–October 2014–Revised April 2015
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UV2
IN,UVLO(rising) UVLO(TH) UV1
R
V V 1 R
§ ·

¨ ¸
© ¹
IN(HYS) UVLO(HYS) UV2
V I Ru
OUT
FB2
FB1 REF
V
R1
R V

OUT
sw 10
ON
V
F Hz
R 1 10 u u
www.ti.com Setup
(1)
The output voltage is set by using the feedback divider resistors R7 (RFB1) and R6 (RFB2) in the EVM by
using Equation 2:
(2)
The EN/UVLO resistors R2 (RUV1) and R1 (RUV2) in the EVM set the input under-voltage lockout threshold
and hysteresis according to Equation 3:
(3)
and,
(4)
3.3 FPWM Mode Selection
Use the FPWM pin to select between the continuous conduction mode (CCM) and the discontinuous
conduction mode (DCM) of operation. Table 1 summarizes the LM5160NDTBKEVM Jumper (JP1) settings
that are chosen to activate the desired mode of operation. Refer to the LM5160 datasheet (SNVSA03A)
for more detailed information regarding the FPWM mode selection.
Table 2. FPWM Pin Mode
JP1 Shunt Setting Logic Stage Description
The FPWM pin is grounded or left floating. DCM
DCM or Floating (High Z) 0 enabled at light loads.
The FPWM pin is connected to VCC. Enables CCM at
FPWM (VCC) 1 light loads.
4 Board Layout
Figure 1. EVM Component View with LM5160A Figure 2. EVM Top Copper View with LM5160A
5
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2.2μF
C1
2.2μF
C10
0.47μF
C2
TP1
DNP
DNP
R9
127k
R1
18.2k
R2
169k
R3
DNP
R5
1 2 3
JP1
0.022uF
C3
0.01μF
C4
C6
DNP
3.01k
R6
2.00k
R7
0.47
R8
10μF
C9
10μF
C8
TP2
1
23
Q1
DNP
GND
GND
GND GND
GND
GND GND
0
R4
1 Fμ
C5
C7
DNP
1
2
J1
1
2
J2
VIN 10 - 60VDC
VOUT 5VDC @ 1.5A
AGND
1
PGND
2
VIN
3
EN/UVLO
4
RON
5
SS
6FPWM 7
FB 8
VCC 9
BST 10
SW 11
SW 12
PAD
U1
LM5160DNT
L1
47uH
GND
Schematic www.ti.com
Figure 3. EVM Bottom Copper View with LM5160A Figure 4. EVM Top Solder Mask with LM5160A
Figure 1 to Figure 4 show the board layout for the LM5160DNTBKEVM PCB. The WSON-12 package
allows a compact leadless IC package buck regulator solution. The LM5160DNTBKEVM is a simple two
layer board. In this EVM, the necessary feedback ripple voltage ( VFB ) required for stable COT operation
over the entire input voltage range is generated by the inductor current flowing through the resistor, RESR
(R8 as shown in Figure 1). This is the least component, minimum cost ripple configuration. There are
placeholders in the EVM ( R7, C6, and C7) which can be populated as required, for the minimum ripple
injection network. If this external ripple configuration is used, substitute R8 with a 0Ω(0805) resistor.
Calculate these component values based on the formulae mentioned under Type 3 ripple configuration in
the LM5160, LM5160A Datasheet (SNVSA03A). See application note AN-1481 for more details for each
ripple generation method.
5 Schematic
Figure 5. Buck EVM Schematic with LM5160
When/If used with LM5160, the placeholder for D1 as in Figure 1, must remain unpopulated under all
cases. When evaluating the LM5160A, the designer needs to use the same standard EVM by replacing
the LM5160 IC (when/if populated) with the LM5160A. No other components on board need to be
replaced or removed. With LM5160A IC, the designer can use other nominal output voltage (VOUT), set
between 9 V and 13 V, to externally drive the VCC for improved efficiency requirement. In that case, the
diode in placeholder D1 can be appropriately populated, to the correct voltage ratings. More detail is given
in Section 6 in the Bill of Materials. For more information about the difference between LM5160A and
LM5160, please refer to the LM5160 Datasheet (SNVSA03A).
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4.975
4.985
4.995
5.005
5.015
5.025
0.00 0.25 0.50 0.75 1.00 1.25 1.50
Output Voltage (V)
Load Current (A)
Vin = 12V
Vin = 24V
Vin = 48V
C002
0
10
20
30
40
50
60
70
80
90
100
0.00 0.25 0.50 0.75 1.00 1.25 1.50 1.75
Efficiency (%)
Load Current (A)
Vin = 12V
Vin = 24V
Vin = 48V
C001
www.ti.com LM5160DNTBKEVM Bill of Materials for 300 kHz Configuration
6 LM5160DNTBKEVM Bill of Materials for 300 kHz Configuration
ITEM DESCRIPTION MFG. PART NUMBER PACKAGE VALUE
C1, C10 Ceramic Capacitor Murata GRM32ER72A225KA35L 1210 2.2µF, 100V, ±10%, X7R
C2 Ceramic Capacitor Murata GRM21BR72A474KA73L 0805 0.47µF, 100V, ±10%, X7R
C3 Ceramic Capacitor Murata GRM188R71C223KA01D 0603 0.022µF, 16V, ±10%, X7R
C4 Ceramic Capacitor Murata GRM188R71C103KA01D 0603 0.01µF, 16V, ±10%, X7R
C5 Ceramic Capacitor Murata GRM188R71E105KA12D 0603 1µF, 25V, ±10%, X7R
C8, C9 Ceramic Capacitor Murata GRM21BR71A106KE51L 0805 10µF, 10V, ±10%, X7R
JP1 Header Sullins Connector PEC03SAAN 3x1, Tin plated
10mm x
L1 Inductor Coiltronics DR125-470-R 47µH, 2.71A, 0.074 Ω, SMD
12.5mm
R1 Resistor Yageo America RC0603FR-07127KL 0603 127 kΩ, 1%, 0.1W
R2 Resistor Vishay-Dale CRCW060318K2FKEA 0603 18.2 kΩ, 1%, 0.1W
R3 Resistor Yageo America RC0603FR-07169KL 0603 169 kΩ, 1%, 0.1W
R4 Resistor Yageo America RC0805JR-070RL 0805 0 Ω, 5%, 0.125W
R6 Resistor Vishay-Dale CRCW06033K01FKEA 0603 3.01 kΩ, 1%, 0.1W
R7 Resistor Vishay-Dale CRCW06032K00FKEA 0603 2.00 kΩ, 1%, 0.1W
R8 Resistor Panasonic ERJ-6RQFR47V 0805 0.47 Ω, 1%, 0.125W
U1 Switching Regulator Texas Instruments LM5160ADNT WSON-12
R5 Resistor Unpopulated 0603
R9 Resistor Unpopulated 0603 18.2 kΩ, 1%, 0.1W
C6 Ceramic Capacitor Unpopulated 0603
C7 Ceramic Capacitor Unpopulated 0603
Schottky Diode (Use with
D1 Diodes Inc. B0530W-7-F (Unpopulated) SOD-123 30 V, 0.5 A
LM5160A only)
Q1 MOSFET Unpopulated SOT-323 N-CH, 50V, 0.2A
7 Performance Curves with LM5160A, LM5160
Figure 6. Load Regulation Figure 7. Efficiency vs. IOUT
7
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Input Voltage (V)
Efficiency (%)
5 15 25 35 45 55 65
60
70
80
90
100
IO= 0.5A
IO= 1A
IO= 1.5A
Load Current (A)
Efficiency (%)
0.005 0.01 0.05 0.1 0.5 1 1.5
20
50
100
FPWM = 0
FPWM = 1
Vin =12V
Vin = 24V
Vin = 48V
Performance Curves with LM5160A, LM5160 www.ti.com
Figure 9. Efficiency DCM vs. CCM at 300kHz
Figure 8. Efficiency vs. VIN
Figure 10. VIN = 48V and FPWM = 0 at no load Figure 11. VIN = 48V and FPWM = 0 at no load (Zoomed)
Figure 12. VIN = 48V and FPWM = 1 at no load Figure 13. Load Transient (IO= 300mA to 1.5A)
8LM5160A, LM5160 User’s Guide SNVU441B–October 2014–Revised April 2015
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VSW (20 V/div)
iLIND (500 mA/div)
VOUT (5 V/div)
VSS (2 V/div)
Time = 50 µs/div)
www.ti.com Performance Curves with LM5160A, LM5160
Figure 14. Startup at RLOAD = 3ΩFigure 15. Pre-Bias Startup at RLOAD = 3Ωand VIN = 48V
Figure 17. EN/UVLO Startup at RLOAD = 100Ωand VIN = 24V
Figure 16. EN/UVLO Startup at RLOAD = 5Ωand VIN = 24V
Figure 18. Output Short-Circuit at VIN = 48V
9
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Revision History www.ti.com
Revision History
Changes from A Revision (February 2015) to B Revision ............................................................................................. Page
• Added information for LM5160A EVM.................................................................................................. 4
• Added updated EVM views with LM5160A ............................................................................................ 5
NOTE: Page numbers for previous revisions may differ from page numbers in the current version.
10 Revision History SNVU441B–October 2014–Revised April 2015
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