Texas Instruments LM5160 User manual

LM5160 Fly-Buck (Isolated Buck) User’s Guide
User's Guide
Literature Number: SNVU408A
October 2014–Revised February 2015

Contents
1 Introduction......................................................................................................................... 4
2 Background......................................................................................................................... 4
3 Setup.................................................................................................................................. 4
3.1 Input/Output Connector Description ................................................................................... 4
3.2 Operation.................................................................................................................. 5
4 Board Layout....................................................................................................................... 5
5 Schematic ........................................................................................................................... 6
6 Bill of Materials.................................................................................................................... 7
7 Performance Curves with LM5160 .......................................................................................... 9
Revision History.......................................................................................................................... 11
2Table of Contents SNVU408A – October 2014 – Revised February 2015
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List of Figures
1 Top Assembly Layer......................................................................................................... 5
2 Top Copper ................................................................................................................... 5
3 Bottom Copper ............................................................................................................... 6
4 LM5160 Fly-Buck EVM Schematic ........................................................................................ 6
5 Fly-Buck Schematic with LM5160A ....................................................................................... 7
6 Line and Load Regulation .................................................................................................. 9
7 Efficiency vs IOUT2 with Default Board Configuration ..................................................................... 9
8 Efficiency vs IOUT2 with Alternate Configuration........................................................................... 9
9 Load Transient at VIN = 24 V IOUT2 = 100 mA to 300 mA ................................................................ 9
10 VIN Startup Waveform at IOUT2 = 200 mA and IOUT1 = 0 A ................................................................ 9
11 Primary Switch Node at VIN = 24 V and IOUT2 = 200 mA................................................................. 9
12 Secondary-side Short at IOUT2 = 600 mA and IOUT1 = 200mA (Tx: Wurth Elektronik #: 744873220).............. 10
List of Tables
1 Default Board Specification with LM5160 ................................................................................ 4
2 Alternate Configuration with LM5160 ..................................................................................... 4
3 LM5160DNTFBKEVM Bill of Materials for 300 kHz Configuration .................................................... 7
4 Bill of Materials for Alternate Configuration .............................................................................. 8
3
SNVU408A – October 2014 – Revised February 2015 List of Figures
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OUTISO OUT1 F
N2
V V V
N1
u 
§ ·
 u
¨ ¸
© ¹
OUT1 R8
V 1 2 V
R9
OUT1
SW 10 ON
V
¦1 10 R

u u
www.ti.com Setup
3.2 Operation
For proper operation of the Fly-Buck converter, gradually increase the input voltage applied across J3.
The load on the secondary output (J1) with primary output (J2) unloaded, should not exceed 400 mA
which corresponds to 30 Ω. If the primary is loaded, the combined load on the two outputs should not
exceed 600 mA. The coupled inductor (transformer) T1 utilized in this board is optimized for small solution
size and is not rated for the peak current limit of LM5160. If short circuit protection is required, T1 should
be replaced with a coupled inductor (flyback transformer) with primary side saturation current rating
greater than the peak current limit of LM5160.
When the input voltage exceeds approximately 18 V, the primary and secondary outputs (J2 and J1)
power up to approximately 8 V and 12 V respectively.
The frequency of operation is set using the RON resistor (R7)
(1)
The primary output voltage can be set with the feedback divider resistors R8 and R9, using the following
equation:
(2)
The secondary output is related to the primary output voltage by the transformer turns ratio:
(3)
where N2/N1 is the turns ratio and VFis the forward voltage drop of the secondary rectifier diode. There is
some additional drop because of the leakage inductance and resistance of windings.
4 Board Layout
Figure 1,Figure 2, and Figure 3 show the board layout for the LM5160DNTFBKVM PCB. The WSON
package offers an exposed thermal pad for enhanced thermal performance. The IC must be soldered
properly to the copper landing on the PCB for optimal performance. The EVM is a two layer board.
Figure 2. Top Copper
Figure 1. Top Assembly Layer
5
SNVU408A – October 2014 – Revised February 2015 LM5160 User’s Guide
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User's Guide
SNVU408A– October 2014–Revised February 2015
LM5160 User’s Guide
1 Introduction
The LM5160NDNTFBKEVM evaluation module (EVM) helps designers evaluate the operation and
performance of the LM5160 in the Fly-Buck™ (isolated buck) configuration. The Fly-Buck topology is
derived from the synchronous buck topology by replacing the buck inductor with a coupled inductor
(transformer) to produce both primary (non-isolated) and secondary (isolated) outputs. This user guide
details the specification of the EVM and includes complete application schematic, bill of materials (BOM),
setup instructions, and performance curves. 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.
2 Background
The application schematic is designed to operate from a 24 V nominal bus with the input voltage ranging
from 18 V to 32 V. It is capable of supplying 12 V with the secondary load rated to 400 mA at the isolated
output. The nominal switching frequency is 300 kHz. The high side and low side MOSFETs are integrated
in the LM5160 and LM5160A. The EVM is designed to demonstrate a small solution size in the WSON-12
lead-less package for low power isolated bias applications.
Table 1. Default Board Specification with LM5160
INPUT FREQUENCY VOUT1 ISOLATED VOUT IOUT
VIN = 18 V – 32 V 300 kHz 8 V 12 V 0 – 400 mA
The EVM can also be arranged with an alternate configuration shown in Table 2 using some simple
modifications. The changes in the BOM for the alternate configuration is shown in Table 4. This
configuration is optimized for lower power, high efficiency application.
Table 2. Alternate Configuration with LM5160
INPUT FREQUENCY VOUT1 ISOLATED VOUT IOUT
VIN = 18 V – 32 V 160 kHz 10 V 15 V 0-200 mA
3 Setup
This section describes the connectors and test-points on the EVM as well as how to properly connect,
setup and use the LM5160DNTFBKEVM with the LM5160.
3.1 Input/Output Connector Description
J1 – Output is the isolated output voltage for the converter. The terminal block provides VOUTISO (+) and
isolated ground (-) connection to allow the user to attach the EVM to a load.
J2 – Output is the primary non-isolated regulated output voltage for the converter. The terminal block
provides VOUT1 (+) and ground (-) connection to allow the user to attach the EVM to a load.
J3 – Input is the power input terminal for the converter. The terminal block provides input VIN(+) and
ground (-) connections to allow the user to attach the EVM to a power supply.
TP1 – (SW1) allows the user to connect a scope probe to observe the primary side switching node of the
converter.
4LM5160 User’s Guide SNVU408A– October 2014 – Revised February 2015
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0.47µF
C8
127k
R6
10.0k
R10
301k
R7
51.1k
R4
0.082µF
C13
0.01µF
C5
1000pF
C4
6.04K
R8
2.00k
R9
10µF
C11
10µF
C10
TP1
GND
GND
GND
GND GND GND
0
R3
1µF
C12
0.1µF
C9
GND ISOGND
D1
DFLS1100-7
2.0k
R2
10µF
C1
10µF
C2
GND
2200pF
C3
1
2
J3
1
2
J1
1
2
J2
12VOUT
18-32VIN
0
R1
1
6
3
4
T1
750314597
GND
VOUTISO
VIN
2.2uF
C6
2.2uF
C7
VOUT
1
J4 8VOUTAGND
1
PGND
2
VIN
3
EN/UVLO
4
RON
5
SS
6FPWM 7
FB 8
VCC 9
BST 10
SW 11
SW 12
PAD
LM5160DNT
Schematic www.ti.com
Figure 3. Bottom Copper
5 Schematic
Figure 4. LM5160 Fly-Buck EVM Schematic
Figure 5 below shows the Fly-buck configuration using LM5160A with the VCC being powered from the
VOUT (8VOUT, Primary) through diode D2 for improved efficiency requirements. When evaluating the
LM5160A, the designer can use the standard LM5160DNTFBKEVM by simply replacing the LM5160 IC
with the LM5160A. No other components on board need to be replaced or removed. In the standard EVM,
when used with the LM5160, the placeholder for diode D2, as given in Figure 1, must remain unpopulated
under all cases. For more information about the difference between the LM5160A and the LM5160, please
refer to the LM5160 Datasheet (SNVSA03).
6LM5160 User’s Guide SNVU408A– October 2014 – Revised February 2015
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0.47µF
C8
127k
R6
10.0k
R10
301k
R7
51.1k
R4
0.082µF
C13
0.01µF
C5
1000pF
C4
6.04K
R8
2.00k
R9
10µF
C11
10µF
C10
TP1
D2
B0530W-7-F
GNDGND GND GND GND GND
0
R3
1µF
C12
0.1µF
C9
GND ISOGND
D1
DFLS1100-7
2.0k
R2
10µF
C1
10µF
C2
GND
2200pF
C3
1
2
J3
1
2
J1
1
2
J2
12VOUT
18-32VIN
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
13
U1
LM5160A
0
R1
1
6
3
4
T1
750314597
GND
VOUTISO
VIN
2.2µF
C6
2.2µF
C7
VOUT
VOUT
1
J4
1040
8VOUT
www.ti.com Bill of Materials
Figure 5. Fly-Buck Schematic with LM5160A
6 Bill of Materials
Table 3. LM5160DNTFBKEVM Bill of Materials for 300 kHz Configuration
COUNT REF DES DESCRIPTION SIZE MFR PART NUMBER
4 C1, C2, CAP, CERM, 10 µF, 35 V, ±10%, X7R, 1210 MuRata GRM32ER7YA106KA12L
C10, C11
1 C3 CAP, CERM, 2200 pF, 2000 V, ±10%, X7R 1812 TDK C4532X7R3D222K
1 C4 CAP, CERM, 1000 pF, 16 V, ±10%, X7R 603 MuRata GRM188R71C102KA01D
1 C5 CAP, CERM, 0.01 µF, 16 V, ±10%, X7R 603 MuRata GRM188R71C103KA01D
2 C6, C7 CAP, CERM, 2.2 µF, 100 V, X7R, 10% 1210 Murata GRM32ER72A225KA35K
1 C8 CAP, CERM, 0.47 µF, 100 V, ±10%, X7R 805 MuRata GRM21BR72A474KA73L
1 C9 CAP, CERM, 0.1 µF, 25 V, ±5%, X7R 603 AVX 06033C104JAT2A
1 C12 CAP, CERM, 1 µF, 16 V, ±10%, X7R 603 TDK C1608X7R1C105K
1 C13 CAP, CERM, 0.082 µF, 16 V, ±10%, X7R 603 MuRata GRM188R71C823KA01D
1 D1 Diode, Schottky, 100 V, 1 A PowerDI123 Diodes Inc. DFLS1100-7
1 D2 Diode, Schottky, 30 V, 0.5 A (LM5160A only) SOD-123 Diodes Inc. B0530W-7-F(Unpopulated)
3 J1, J2, J3 Terminal Block, 6 A, 3.5 mm Pitch, 2-Pos, TH 7.0x8.2x6.5 On-Shore ED555/2DS
mm Technology
2 R1, R3 RES, 0 Ω, 5%, 0.125 W 805 Vishay-Dale CRCW08050000Z0EA
1 R2 RES, 2.0 kΩ, 5%, 0.125 W 805 Vishay-Dale CRCW08052K00JNEA
1 R4 RES, 51.1 kΩ, 1%, 0.1 W 603 Yageo RC0603FR-0751K1L
1 R6 RES, 127 kΩ, 1%, 0.1 W 603 Yageo RC0603FR-07127KL
1 R7 RES, 301 kΩ, 1%, 0.1 W 603 Vishay-Dale CRCW0603301KFKEA
1 R8 RES, 6.04 kΩ, 1%, 0.1 W 603 Vishay-Dale CRCW06036K04FKEA
1 R9 RES, 2.00 kΩ, 1%, 0.1 W 603 Vishay-Dale CRCW06032K00FKEA
1 R10 RES, 10.0 kΩ, 1%, 0.1 W 603 Vishay-Dale CRCW060310K0FKEA
1 T1 Transformer, 60 uH, SMT, 0.840 A 13.36x8.64x Wurth 750314597
10.16 mm Elektronik
1 TP1 Test Point, Multipurpose, Yellow, TH Testpoint Keystone 5014
1 U1 IC, PWM, COT Regulator DNT0012B Texas LM5160DNT
Instruments
7
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Bill of Materials www.ti.com
Table 4. Bill of Materials for Alternate Configuration
COUNT REF DES DESCRIPTION SIZE MFR PART NUMBER
4 C1, C2, CAP, CERM, 10 µF, 35 V, ±10%, X7R, 1210 MuRata GRM32ER7YA106KA12L
C10, C11
1 C3 CAP, CERM, 2200 pF, 2000 V, ±10%, X7R 1812 TDK C4532X7R3D222K
1 C4 CAP, CERM, 1000 pF, 16 V, ±10%, X7R 603 MuRata GRM188R71C102KA01D
1 C5 CAP, CERM, 0.01 µF, 16 V, ±10%, X7R 603 MuRata GRM188R71C103KA01D
2 C6, C7 CAP, CERM, 2.2 µF, 100 V, X7R, 10% 1210 Murata GRM32ER72A225KA35K
1 R8 RES, 8.2 kΩ, 1%, 0.1 W, 0603 603 Standard Standard
1 R7 RES, 698 kΩ, 1%, 0.1 W, 0603 603 Standard Standard
1 C4 CAP, CERM, 3300 pF, 16 V, ±10%, X7R 603 Standard Standard
1 R2 RES, 5.1 kΩ, 5%, 0.125 W 805 Standard Standard
1 D1 Diode, Schottky, 60 V, 1A PowerDI123 Diodes Inc. DFLS160-7
1 C8 CAP, CERM, 0.47 µF, 100 V, ±10%, X7R 805 MuRata GRM21BR72A474KA73L
1 C9 CAP, CERM, 0.1 µF, 25 V, ±5%, X7R 603 AVX 06033C104JAT2A
1 C12 CAP, CERM, 1 µF, 16 V, ±10%, X7R 603 TDK C1608X7R1C105K
1 C13 CAP, CERM, 0.082 µF, 16 V, ±10%, X7R 603 MuRata GRM188R71C823KA01D
1 D1 Diode, Schottky, 100 V, 1 A PowerDI123 Diodes Inc. DFLS1100-7
1 D2 Diode, Schottky, 30 V, 0.5 A (LM5160A only) SOD-123 Diodes Inc. B0530W-7-F(Unpopulated)
3 J1, J2, J3 Terminal Block, 6 A, 3.5 mm Pitch, 2-Pos, TH 7.0x8.2x6.5 On-Shore ED555/2DS
mm Technology
2 R1, R3 RES, 0 Ω, 5%, 0.125 W 805 Vishay-Dale CRCW08050000Z0EA
1 R4 RES, 51.1 kΩ, 1%, 0.1 W 603 Yageo RC0603FR-0751K1L
1 R6 RES, 127 kΩ, 1%, 0.1 W 603 Yageo RC0603FR-07127KL
1 R7 RES, 301 kΩ, 1%, 0.1 W 603 Vishay-Dale CRCW0603301KFKEA
1 R9 RES, 2.00 kΩ, 1%, 0.1 W 603 Vishay-Dale CRCW06032K00FKEA
1 R10 RES, 10.0 kΩ, 1%, 0.1 W 603 Vishay-Dale CRCW060310K0FKEA
1 T1 Transformer, 60 uH, SMT, 0.840 A 13.36x8.64x Wurth 750314597
10.16 mm Elektronik
1 TP1 Test Point, Multipurpose, Yellow, TH Testpoint Keystone 5014
1 U1 IC, PWM, COT Regulator DNT0012B Texas LM5160DNT
Instruments
8LM5160 User’s Guide SNVU408A– October 2014 – Revised February 2015
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IOUT2 (A)
Efficiency (%)
0 0.05 0.1 0.15 0.2 0.25
50
55
60
65
70
75
80
85
90
95
D003
VIN = 18V
VIN = 24V
VIN = 32V
8
9
10
11
12
13
14
0.0 0.1 0.2 0.3 0.4 0.5
Isolated Sec. Output Voltage (V)
Secondary Load Current (A)
Vin = 18V
Vin = 24V
Vin = 32V
C002
www.ti.com Performance Curves with LM5160
7 Performance Curves with LM5160
Figure 7. Efficiency vs IOUT2 with Default Board
Figure 6. Line and Load Regulation
Configuration
Figure 9. Load Transient at VIN = 24 V
IOUT2 = 100 mA to 300 mA
Figure 8. Efficiency vs IOUT2 with Alternate Configuration
9
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Performance Curves with LM5160 www.ti.com
Figure 11. Primary Switch Node at VIN = 24 V
Figure 10. VIN Startup Waveform at IOUT2 = 200 mA
and IOUT2 = 200 mA
and IOUT1 = 0 A
Figure 12. Secondary-side Short at IOUT2 = 600 mA
and IOUT1 = 200mA (Tx: Wurth Elektronik #: 744873220)
10 LM5160 User’s Guide SNVU408A– October 2014 – Revised February 2015
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