IRDC3891 - International Rectifier

IRDC3891
SupIRBuck
TM
USER GUIDE FOR IR3891 EVALUATION BOARD
DESCRIPTION
The IR3891 is a dual synchronous buck
converter, providing a compact, high
performance and flexible solution in a small
5mm X 6mm Power QFN package.
Key features offered by the IR3891 include
internal Digital Soft Start, precision 0.5V
reference voltage, Power Good, thermal
protection,
programmable
switching
frequency, Enable input, input under-voltage
lockout for proper start-up, enhanced line/
load regulation with feed forward, external
frequency synchronization with smooth
clocking, internal LDO, pre-bias start-up,
output over voltage protection as well as open
feedback line protection.
Output over-current protection function is
implemented by sensing the voltage developed
across the on-resistance of the synchronous
rectifier MOSFET for optimum cost and
performance and the current limit is thermally
compensated.
This user guide contains the schematic and bill
of materials for the IR3891 evaluation board.
The guide describes operation and use of the
evaluation board itself. Detailed application
information for IR3891 is available in the
IR3891 data sheet.
BOARD FEATURES
• Vin = +5.0V
• Fs = 700kHz
• Vout1 = +2.5V @ 4A
Vout2 = +1.8V @ 4A
• L1 = 2.2uH
L2 = 2.2uH
• Cout1=4x22uF (ceramic 0805)
Cout2=4x22uF (ceramic 0805)
• Cin= 4x10uF (ceramic 1206) + 1x330uF (electrolytic)
10-01-2012
Confidential
This evaluation board is a preliminary version meant for the engineering
evaluation of the IR3891. Based on the results of the continuing
evaluation, this board can evolve and change without notice.
1
IRDC3891
CONNECTIONS and OPERATING INSTRUCTIONS
A well regulated +5.0V input supply should be connected to VIN+ and VIN-. A maximum 4A load should be
connected to VOUT+ and VOUT-. The connection diagram is shown in Fig. 1 and inputs and outputs of the
board are listed in Table I.
IR3891 has only one input supply and internal LDO generates Vcc from Vin. If operation with external Vcc
is required, then R3 should be removed and external Vcc should be applied between Vcc+ and Vcc- pins.
Vin pin (input of the LDO) and Vcc/LDO pins should be shorted together (populate R4) for external Vcc
operation.
The output of channel2 (Vout2) can follow the voltage at the Seq pin. For this purpose, The value of R5 and
R6 can be selected to provide the desired sequencing ratio between Seq input and Vout2. For normal
operation (non-sequencing) Seq pin should be left floating. Seq pin is internally pulled up to 3.3V.
Table I. Connections
Connection
Signal Name
VIN+
PVin (+5V)
VIN-
Ground of PVin
VOUT1+
Vout1 (+2.5V)
VOUT1-
Ground of Vout1
VOUT2+
Vout2 (+1.8V)
VOUT2-
Ground of Vout2
VCC+
VCC/LDO pin
VCC-
Connected to PGND
VSEQ
Sequence input
EN1, EN2
Enable input of each channel
Sync
Synchronous input
LAYOUT
The PCB is a 4-layer board. All of layers are 2 Oz. copper. The IR3891 and other components are
mounted on the top and bottom side of the board.
Power supply decoupling capacitors, the Bootstrap capacitor and feedback components are located
close to IR3891. The feedback resistors are connected to the output voltage at the point of regulation
and are located close to IR3891. To improve efficiency, the circuit board is designed to minimize the
length of the on-board power ground current path.
10-01-2012
Confidential
This evaluation board is a preliminary version meant for the engineering
evaluation of the IR3891. Based on the results of the continuing
evaluation, this board can evolve and change without notice.
2
IRDC3891
Connection Diagram
V OUT1
V OUT2
GROUND
GROUND
PGood1
SEQ
PGood2
Sync
Vsns1
EN1
Vsns2
EN2
VPG
Vcc/LDO_out
Vin
GROUND
Fig. 1: Connection diagram of IR3891 evaluation board (top and bottom)
10-01-2012
Confidential
This evaluation board is a preliminary version meant for the engineering
evaluation of the IR3891. Based on the results of the continuing
evaluation, this board can evolve and change without notice.
3
IRDC3891
R50 is the
Single point
connection
between AGND
and PGND.
Fig. 2: Board layout, top layer
Fig. 3: Board layout, bottom layer
10-01-2012
Confidential
This evaluation board is a preliminary version meant for the engineering
evaluation of the IR3891. Based on the results of the continuing
evaluation, this board can evolve and change without notice.
4
IRDC3891
Fig. 4: Board layout, mid-layer I
Fig. 5: Board layout, mid-layer II
10-01-2012
Confidential
This evaluation board is a preliminary version meant for the engineering
evaluation of the IR3891. Based on the results of the continuing
evaluation, this board can evolve and change without notice.
5
1
1
J111
JUMPER1
J211
Vin
Vcc-
21k
R19
N/S
N/S
21k
R29
41.2K
R28
EN1
C113
C213
R211
N/S
N/S
R111
41.2K
330uF/25V
R18
JUMPER1
Vin-
Vin-
1
+ C1
Vcc+
EN2
N/S
C29
VCC
N/S
C19
C212
10uF
VSeq
N/S
C7
C211
10uF
C112
R5
0
N/S
R6
2.2uF
C8
10uF
N/S
C9
C6
1.0uF
C111
10uF
0
R4
0
Confidential
This evaluation board is a preliminary version meant for the engineering
evaluation of the IR3891. Based on the results of the continuing
evaluation, this board can evolve and change without notice.
34K
R9
Seq
GND1
Vcc/LDO
Vin
EN1
Vsns1
R11
4.87k
C11
5.6nF
IR3891
Vsns2
17
0.1uF
C20
Vpg
0
Vin Vpg
R20
PGood2
NS
C27
C22
100pF
R26
R27
2.61K
6.81k
NS
R22
R15
20
B1
C122
22uF
C123
22uF
C124
22uF
C125
22uF
C126
N/S
C127 C128
N/S N/S
A2
20
R25
B2
C222
22uF
C223
22uF
C224
22uF
C225
22uF
0
R50
C226
N/S
C129 V1
N/S
Agnd Agnd
1
1
1
Vout1+
Vout2-
Vout2-
Vout2-
Vout2+
Vout2+
Vout2+
Vout1-
Vout1-
Vout1-
Vout1+
Vout1+
Agnd Agnd Agnd Agnd Agnd
1
1
1
C221
0.1uF
Vout2
1
1
1
C121
0.1uF
1
1
Vout1 1
C228C229
N/S N/S V2
PGNDPGND PGND
Agnd
C227
N/S
Output ceramic: 0805 (use 1206 footprint)
C23
A1
2200pF
6.81k
R23
2.61K
10
R24
2.2uH
L2
R21
R2
49.9K
VCC
SW22
2.2uH
L1
7.15K
C26
R8
N/S
SW2
R12
6.19k
C21
C24
0.1uF
13
14
15
16
0.1uF
SW11
C13
2200pF
5.6nF
Boot2
PVin2
PGnd2
SW2
SW1
PGnd1
18
C14
0.1uF
C10
0
R10
SW1
R13
1.54k
69.8
R14
Fig.6: Schematic of the IR3891 evaluation board
DIODE
D1
6
5
4
3
2
1
U1
6.19k
C12
100pF
R17
1.54k
R7
N/S
Vpg
R1
49.9K
VCC
PGood1
SY NC
R3
1
Input ceramic: 1206
1
NS
GND2
Vin-
1
2
1
2
22
Comp1
1
1
PVin1
Vin+
1
Boot1
C17
7
FB1
9
1
Vin+
1
FB2
10
24
Rt/Sync
21
PGood1
11
23
EN2
8
20
Comp2
19
PGood2
12
1
1
1
1
1
1
1
1
1
1
1
1
1
1
R16
1
Vin
1
1
1
1
Vsns2
1
1
1
NS
1
C16
1
Vsns1
1
10-01-2012
1
Vin+
IRDC3891
6
IRDC3891
Bill of Materials
Vin=5.0V, Vout1=2.5V/4A, Vout2=1.8V/4A, fs=700KHz
Item
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
Qty
Part Reference
1 C1
4 C111 C112 C211 C212
1 C6
1 C8
6 C10 C14 C20 C24 C121 C221
1 C11
1 C12
2 C13 C23
1 C21
1 C22
C122 C123 C124 C125
8
C222 C223 C224 C225
1 L1
1 L2
2 R1 R2
6 R3 R4 R5 R10 R20 R50
1 R9
1 R11
2 R12 R16
2 R13 R17
1 R14
2 R15 R25
2 R18 R28
2 R19 R29
1 R21
2 R22 R26
2 R23 R27
1 R24
2 R111 R211
2 J111 J211
1 R6
C7 C9 C16 C17 C19 C26 C27
16 C29 C113 C126 C127 C128
C213 C226 C227 C228
1 D1
1 U1
10-01-2012
Value
330uF
10uF
1.0uF
2.2uF
0.1uF
5.6nF
100pF
2200pF
5.6nF
100pF
22uF
2.2uH
2.2uH
49.9K
0
34K
4.87K
6.19K
1.54K
69.8
20
41.2K
21K
7.15K
6.81K
2.61K
10
N/S
jumper
N/S
Description
Manufacturer
Part Number
SMD Electrolytic F size 25V 20%
1206, 25V, X5R, 10%
0603, 25V, X5R, 10%
0603, 16V, X5R, 20%
0603, 25V, X7R, 10%
0603, 50V, X7R, 10%
0603, 50V, NP0, 5%
0603, 50V, X7R, 10%
0603, 50V, X7R, 10%
0603, 50V, NP0, 5%
Panasonic
TDK
Murata
TDK
Murata
Murata
Murata
Murata
Murata
Murata
EEV-FK1E331P
C3216X5R1E106K
GRM188R61E105KA12D
C1608X5R1C225M
GRM188R71E104KA01B
GRM188R71H562KA01D
GRM1885C1H101JA01D
GRM188R71H222KA01D
GRM188R71H562KA01D
GRM1885C1H101JA01D
0805, 6.3V, X5R, 20%
TDK
C2012X5R0J226M
SMD 8.4x7.9x7.2mm,DCR=4.4mΩ
SMD 8.4x7.9x7.2mm,DCR=4.4mΩ
Thick Film, 0603,1/10W,1%
Thick Film, 0603,1/10W
Thick Film, 0603,1/10W,1%
Thick Film, 0603,1/10W,1%
Thick Film, 0603,1/10W,1%
Thick Film, 0603,1/10W,1%
Thick Film, 0603,1/10W,1%
Thick Film, 0603,1/10W,1%
Thick Film, 0603,1/10W,1%
Thick Film, 0603,1/10W,1%
Thick Film, 0603,1/10W,1%
Thick Film, 0603,1/10W,1%
Thick Film, 0603,1/10W,1%
Thick Film, 0603,1/10W,1%
Wurth Elektronik
Wurth Elektronik
Panasonic
Panasonic
Panasonic
Panasonic
Panasonic
Panasonic
Panasonic
Panasonic
Panasonic
Panasonic
Panasonic
Panasonic
Panasonic
Panasonic
7443340220
7443340220
ERJ-3EKF4992V
ERJ-3GEY0R00V
ERJ-3EKF3402V
ERJ-3EKF4871V
ERJ-3EKF6191V
ERJ-3EKF1541V
ERJ-3EKF69R8V
ERJ-3EKF20R0V
ERJ-3EKF4122V
ERJ-3EKF2102V
ERJ-3EKF7151V
ERJ-3EKF6811V
ERJ-3EKF2611V
ERJ-3EKFR10R0V
Vishay
IR
BAS40-02VGS08
IR3891MPBF
This is a simple jumper
N/S
IR3891
Schottky, 40V, SOD-523
PQFN 5x6mm
Confidential
This evaluation board is a preliminary version meant for the engineering
evaluation of the IR3891. Based on the results of the continuing
evaluation, this board can evolve and change without notice.
7
IRDC3891
TYPICAL OPERATING WAVEFORMS
PVin=Vin=Vcc=5.0V, Vout1=2.5V, Vout2=1.8V, Io1= Io2=0-4A, Room Temperature, No Air Flow
Fig. 7: Start up at 4A Load (Note 1)
Ch1:Vout1, Ch2:Vout2, Ch3:Vcc/LDO, Ch4:Vin
Fig. 8: Start up at 4A Load (Note 1)
Ch1:Vout1, Ch2:Vout2, Ch3:PGood1, Ch4: PGood2
Fig. 9: Start up with 1.99V Prebias,
0A Load, Ch1:Vout1, Ch3:PGood1
Fig. 11: Inductor nodes at 4A load
Ch1:SW1, Ch2:SW2
10-01-2012
Fig. 10: Start up with 1.58V Prebias,
0A Load, Ch2:Vout2, Ch4:PGood2
Fig. 12: Output Voltage Ripple, 4A load on each
channel (Note2) Ch1: Vout1, Ch2: Vout2
Confidential
This evaluation board is a preliminary version meant for the engineering
evaluation of the IR3891. Based on the results of the continuing
evaluation, this board can evolve and change without notice.
8
IRDC3891
TYPICAL OPERATING WAVEFORMS
PVin=Vin=Vcc=5.0V, Vout1=2.5V, Vout2=1.8V, Io1= Io2=0-4A, Room Temperature, No Air Flow
Fig. 14: Short circuit (Hiccup) Response
Ch1:Vout2, Ch4:Iout2
Fig. 13: Short circuit (Hiccup) Response
Ch1:Vout1, Ch4:Iout1
10-01-2012
Confidential
This evaluation board is a preliminary version meant for the engineering
evaluation of the IR3891. Based on the results of the continuing
evaluation, this board can evolve and change without notice.
9
IRDC3891
TYPICAL OPERATING WAVEFORMS
PVin=Vin=Vcc=5.0V, Vout1=2.5V, Vout2=1.8V, Room Temperature, No Air Flow
Fig. 15: Transient Response of channel1
0A-1.6A (0-40%), Ch1:Vout1 , Ch2:Vout2, Ch4: Iout1
10-01-2012
Confidential
This evaluation board is a preliminary version meant for the engineering
evaluation of the IR3891. Based on the results of the continuing
evaluation, this board can evolve and change without notice.
10
IRDC3891
TYPICAL OPERATING WAVEFORMS
PVin=Vin=Vcc=5.0V, Vout1=2.5V, Vout2=1.8V, Room Temperature, No Air Flow
Fig. 16: Transient Response of channel2
0A-1.6A (0-40%), Ch1:Vout1 , Ch2:Vout2, Ch4: Iout2
Note1: Enable is tied to Vin via a resistor divider.
Note2: Vo ripple signal is taken across C125 and C225 capacitors.
10-01-2012
Confidential
This evaluation board is a preliminary version meant for the engineering
evaluation of the IR3891. Based on the results of the continuing
evaluation, this board can evolve and change without notice.
11
IRDC3891
Bode Plot, Channel1
PVin=Vin=Vcc=5.0V, Vout1=2.5V, Vout2=1.8V, Io1= Io2=4A, Room Temperature, No Air Flow
Fig.17: Bode Plot of CH1 at 4A load: bandwidth = 97.1 kHz, phase margin = 64.2 degrees, gain margin = 15.4dB
10-01-2012
Confidential
This evaluation board is a preliminary version meant for the engineering
evaluation of the IR3891. Based on the results of the continuing
evaluation, this board can evolve and change without notice.
12
IRDC3891
Bode Plot, Channel2
PVin=Vin=Vcc=5.0V, Vout1=2.5V, Vout2=1.8V, Io1= Io2=4A, Room Temperature, No Air Flow
Fig.18: Bode Plot of CH2 at 4A load: bandwidth = 105.1 kHz, phase margin = 59.8 degrees, gain margin = 14.45dB
10-01-2012
Confidential
This evaluation board is a preliminary version meant for the engineering
evaluation of the IR3891. Based on the results of the continuing
evaluation, this board can evolve and change without notice.
13
IRDC3891
Efficiency and Power Loss of channel1
PVin=Vin=Vcc=5.0V, Vout1=2.5V, Vout2 is disabled (EN2=low), Io1= 0-4A, Room Temperature, No Air Flow
97
95
Efficiency [%]
93
91
89
87
85
83
81
79
77
0.00
0.50
1.00
1.50
2.00
Io [A]
2.50
3.00
3.50
4.00
0.5
1.0
1.5
2.0
Io [A]
2.5
3.0
3.5
4.0
0.8
Power Loss [W]
0.7
0.6
0.5
0.4
0.3
0.2
0.1
0
0.0
Fig.19: Efficiency and power loss vs. load current for channel1 (Vout1 = 2.5V)
10-01-2012
Confidential
This evaluation board is a preliminary version meant for the engineering
evaluation of the IR3891. Based on the results of the continuing
evaluation, this board can evolve and change without notice.
14
IRDC3891
Efficiency and Power Loss of channel2
PVin=Vin=Vcc=5.0V, Vout1 is disabled (EN1=low), Vout2=1.8V, Io2=0-4A, Room Temperature, No Air Flow
97
95
Efficiency [%]
93
91
89
87
85
83
81
79
77
0.00
0.50
1.00
1.50
2.00
Io [A]
2.50
3.00
3.50
4.00
0.5
1.0
1.5
2.0
Io [A]
2.5
3.0
3.5
4.0
0.8
Power Loss [W]
0.7
0.6
0.5
0.4
0.3
0.2
0.1
0
0.0
Fig.20: Efficiency and power loss vs. load current for channel2 (Vout2 = 1.8V)
10-01-2012
Confidential
This evaluation board is a preliminary version meant for the engineering
evaluation of the IR3891. Based on the results of the continuing
evaluation, this board can evolve and change without notice.
15
IRDC3891
Thermal Image
PVin=Vin=Vcc=5.0V, Vout1=2.5V, Vout2=1.8V, Io1= Io2=4A, Room Temperature, No Air Flow
Fig.21: Thermal Image at Io1=Io2=4A load
Test Point 1: IR3891, Test Point 2: Inductor_Ch1, Test Point 3: Inductor_Ch2
10-01-2012
Confidential
This evaluation board is a preliminary version meant for the engineering
evaluation of the IR3891. Based on the results of the continuing
evaluation, this board can evolve and change without notice.
16
IRDC3891
IR WORLD HEADQUARTERS: 233 Kansas St., El Segundo, California 90245, USA Tel: (310) 252-7105
TAC Fax: (310) 252-7903
Visit us at www.irf.com for sales contact information
Data and specifications subject to change without notice. 10/11
10-01-2012
Confidential
This evaluation board is a preliminary version meant for the engineering
evaluation of the IR3891. Based on the results of the continuing
evaluation, this board can evolve and change without notice.