synchronous buck converter using ltspice
Post on 04-Jul-2015
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Synchronous-Buck Converter Circuit
• Synchronous-Buck Converter Circuit
• Test Setup
• Test Circuit
• Synchronous-Buck Controller
• MOSFET: TPC8014
• Inductor L1: Würth Elektronik Inductor
• Capacitor C9: 820uF (25V)
• Switching Waveform
• High Side MOSFET(QH): VGS, VDS, ID
• Low Side MOSFET(QL): VGS, VDS, ID
• Gate Drive Signal
• VIN-VOUT
• VOUT,RIPPLE
• Output Inductor Voltage and Current
All Rights Reserved Copyright (C) Bee Technologies Corporation 2011 1
Synchronous-Buck Converter Circuit
All Rights Reserved Copyright (C) Bee Technologies Corporation 2011 2
Duty Cycle (D)
≈ Vin/Vout,
D = 0.368
Test Setup
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Test Circuit
Power Supply:
VCC 12VVIN 5V
Measurement Waveform
Test Circuit Schematic
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Synchronous-Buck Converter using TPS5618 controller from Texas Instruments
Test Circuit (Breadboard)
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Controller
Q1
Q2
Test Circuit (Top View)
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L1
C9
C10
Controller
Synchronous-Buck Controller (1/2)
Synchronous-Buck Controller Circuit with IC
TPS5618 from Texas Instruments
Synchronous-Buck Controller Block Model
(Open Loop Setting)
• The Syn-Buck_Ctrl is a block model that generates gate drive pulse signal to control MOSFET
switches of the Synchronous-Buck Converter. The duty cycle, switching frequency, and the
switching dead-time are input into the model to match the real circuit.
All Rights Reserved Copyright (C) Bee Technologies Corporation 2011 7
HIDR
LODR
High side gate driver
Low side gate driver
Synchronous-Buck Controller (2/2)
V1
TD = {1/FREQ}
TF = 1n
PW = {D/FREQ}PER = {1/FREQ}
V1 = 0
TR = 1n
V2 = 1.709
PARAMETERS:
FREQ = 152kHz
D = 0.36
tdly = 80n
0
Rdly 1
1k
N4
CHDR
1nCdly 1
{tdly /1k}
00
Rdly 2
1k
N3
0
Cdly 2
{tdly /1k}
HDR
LDR
N1
U1AND2_ABM
VOH = 12VOL = 0
DclmpDHDR1
U2AND2_ABM
VOH = 8VOL = 0
N2
N5
Dclmp
DHDR2
N7
RHDR10.01
U5INV_ABM
VOH = 1.709VOL = 0
RHDR20.01
N6
All Rights Reserved Copyright (C) Bee Technologies Corporation 2011 8
Pulse
Control
Signal
Dead-time
generator
The Syn-Buck_Ctrl Equivalent Circuit
Parameters
• FREQ = Switching frequency, set to match
the measurement switching frequency.
• D = Duty Cycle, calculated by D≈VOUT/VIN
• tdly = HDR and LDR dead-time, the tdly is
set to match the measurement dead time
value.
Gate drive signal (measurement)
1/frequency
Dead-time, the time
when QH and QL
are both off
MOSFET: TPC8014 (1/2)
All Rights Reserved Copyright (C) Bee Technologies Corporation 2011 9
TPC8014 LTSpice Symbol
Device mounted on an epoxy board
*$
*PART NUMBER: TPC8014
*MANUFACTURER: TOSHIBA
*VDSS=30V, ID=11A
*All Rights Reserved Copyright (c) Bee Technologies Inc. 2011
.SUBCKT TPC8014 1 2 3 4 5 6 7 8
X_U1 6 4 3 MTPC8014_p
X_U2 4 3 DZTPC8014
X_U3 3 6 DTPC8014_p
R_R1 1 3 0.01m
R_R2 2 3 0.01m
R_R5 5 6 0.01m
R_R7 7 6 0.01m
R_R8 8 6 0.01m
.ENDS
*$
MOSFET: TPC8014 (2/2)
*$
.SUBCKT MTPC8014_p D G S
CGD 1 G 1.7n
R1 1 G 10MEG
S1 1 D G D SMOD1
D1 2 D DGD
R2 D 2 10MEG
S2 2 G D G SMOD1
M1 D G S S MTPC8014
.MODEL SMOD1 VSWITCH
+ VON=0V VOFF=-10mV RON=1m ROFF=1E12
.MODEL DGD D (CJO=0.950E-9 M=.52396 VJ=.54785)
.MODEL MTPC8014 NMOS
+ LEVEL=3 L=720.00E-9 W=.45 KP=66.000E-6 RS=1.0000E-3
+ RD=6.8436E-3 VTO=2.3063 RDS=3.0000E6 TOX=40.000E-9
+ CGSO=2.7726E-9 CGDO=1E-12 RG=22.95
+ CBD=342.86E-12 MJ=.70573 PB=.3905
+ RB=1 N=5 IS=1E-15 GAMMA=0 KAPPA=0 ETA=0.5m
.ENDS
*$
*$
.SUBCKT DTPC8014_p A K
R_R2 5 6 100
R_R1 3 4 1
C_C1 5 6 195p
E_E1 5 K 3 4 1
S_S1 6 K 4 K _S1
RS_S1 4 K 1G
.MODEL _S1 VSWITCH
+ Roff=50MEG Ron=100m Voff=90mV Von=100mV
G_G1 K A VALUE { V(3,4)-V(5,6) }
D_D1 2 K DTPC8014
D_D2 4 K DTPC8014
F_F1 K 3 VF_F1 1
VF_F1 A 2 0V
.MODEL DTPC8014 D
+ IS=824.87E-12 N=1.2770 RS=6.2420E-3 IKF=7.3139
+ CJO=3.0000E-12 BV=60 IBV=100.00E-6 TT=24.062E-9
.ENDS
*$
.subckt DZTPC8014 1 2
D2 1 3 DZ2
D1 2 3 DZ1
.model DZ1 D
+ IS=0.01p N=0.1 ISR=0
+ CJO=3E-12 BV=22.423 IBV=0.001 RS=0
.model DZ2 D
+ IS=0.01p N=0.1 ISR=0
+ CJO=3E-12 BV=22.423 IBV=0.001 RS=411.11
.ENDS
*$
All Rights Reserved Copyright (C) Bee Technologies Corporation 2011 10
Inductor L1: Würth Elektronik Inductor
*$
*PART NUMBER: L7447140
*MANUFACTURER: Würth Elektronik
*All Rights Reserved Copyright (c) Bee Technologies Inc. 2011
.SUBCKT L7447140 1 2
R_RS 1 N1 10.366m
L_L1 N1 2 4.84796uH
C_C1 N1 2 0.357pF
R_R1 N1 2 15.3375k
.ENDS
*$
All Rights Reserved Copyright (C) Bee Technologies Corporation 2011 11
LTSpice Symbol
Würth Elektronik Inductor part no. 7447140
Capacitor C9: 820uF (25V)
*$
*PART NUMBER: EEUFM1E821L
*MANUFACTURER: Panasonic
*CAP=820uF, Vmax=25V
*All Rights Reserved Copyright (C) Bee Technologies Inc. 2011
.SUBCKT C820U 1 2
L_L1 1 N1 8.16935nH
C_C1 N1 N2 812.73uF
R_R1 N2 2 15.695m
.ENDS
*$
All Rights Reserved Copyright (C) Bee Technologies Corporation 2011 12
LTSpice Symbol
Capacitor 820uF (25V)
Switching Waveform
Measurement Simulation
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V(Vout)
I(L1)
VDS(Q1)
V(Vout)
I(L1)
VDS(Q1)
High Side MOSFET(QH): VGS, VDS, ID
Measurement Simulation
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ID(Q1)
VDS(Q1)
VGS(Q1)
ID(Q1)
VDS(Q1)
VGS(Q1)
Low Side MOSFET(QL): VGS, VDS, ID
Measurement Simulation
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ID(Q2)
VDS(Q2)
VGS(Q2)
ID(Q2)
VDS(Q2)
VGS(Q2)
Gate Drive Signal
Measurement Simulation
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VGS(Q2)
VGS(Q1)
VGS(Q2)
VGS(Q1)
VIN – VOUT
Measurement Simulation
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VOUT
VIN
VOUT
VIN
VOUT,RIPPLE
Measurement Simulation
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VOUT,RIPPLE VOUT,RIPPLE
Output Inductor Voltage and Current
Measurement Simulation
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V(L)
I(L)
V(L)
I(L)
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