MPS MPQ8612-12 High efficiency, 12a/16a/20a, 6v synchronous step-down converter Datasheet

MPQ8612
High Efficiency, 12A/16A/20A, 6V
Synchronous Step-down Converter
The Future of Analog IC Technology
DESCRIPTION
FEATURES
The MPQ8612 is fully integrated high frequency
synchronous rectified step-down switch mode
converter. It offers very compact solutions to
achieve 12A/16A/20A output current from a 3V to
6V input with excellent load and line regulation.
•
•
•
•
Constant-On-Time
(COT)
control
mode
provides fast transient response and eases loop
stabilization. The MPQ8612 can operate with a
low-cost electrolytic capacitor and can support
ceramic output capacitor with external slope
compensation.
•
•
•
•
•
Operating frequency is programmed by an
external resistor and is compensated for
variations in VIN.
•
Under voltage lockout is internally set at 2.8 V,
but can be increased by programming the
threshold with a resistor network on the enable
pin. The output voltage startup ramp is
controlled by the soft start pin. A power good
signal indicates the output is within its nominal
voltage range.
•
•
Wide 3V to 6V Operating Input Range
12A/16A/20A Output Current
Low RDS(ON) Internal Power MOSFETs
Proprietary Switching Loss Reduction
Technique
Adaptive COT for Ultrafast Transient
Response
1% Reference Voltage Over -20°C to
+85°C Junction Temperature Range
Programmable Soft Start Time
Pre-Bias Start up
Programmable Switching Frequency from
300kHz to 1MHz.
Minimum On Time TON_MIN=60ns
Minimum Off Time TOFF_MIN=75ns
Non-latch OCP, non-latch OVP Protection
and Thermal Shutdown
Output Adjustable from 0.608V to 4.5V
APPLICATIONS
•
•
•
•
•
•
Full fault protection including OCP, SCP, OVP
UVP and OTP is provided by internal
comparators.
The MPQ8612 requires a minimum number of
readily available standard external components
and are available in QFN3X4/4X4/4X4 packages.
Telecom System Base Stations
Networking Systems
Server
Personal Video Recorders
Flat Panel Television and Monitors
Distributed Power Systems
All MPS parts are lead-free and adhere to the RoHS directive. For MPS green
status, please visit MPS website under Products, Quality Assurance page.
“MPS” and “The Future of Analog IC Technology” are registered trademarks of
Monolithic Power Systems, Inc.
TYPICAL APPLICATION
VIN
BST
IN
C3
RFREQ
C1
EN
ON/OFF
VCC
VOUT
R4
C4
R1
MPQ8612
C2
FB
VCC
C5
L1
SW
FREQ
SS
R3
R2
C6
PG
PGND
AGND
MPQ8612 Rev. 1.11
www.MonolithicPower.com
10/22/2013
MPS Proprietary Information. Patent Protected. Unauthorized Photocopy and Duplication Prohibited.
© 2013 MPS. All Rights Reserved.
1
MPQ8612 ― 12A/16A/20A, 6V, SYNCHRONOUS STEP-DOWN CONVERTER
ORDERING INFORMATION
Part Number*
Package
MPQ8612GL-12
QFN (3x4mm)
MPQ8612GR-16
QFN (4x4mm)
MPQ8612GR-20
QFN (4x4mm)
Top Marking
MP8612
12
MP8612
16
MP8612
20
* For Tape & Reel, add suffix –Z (e.g. MPQ8612GL–Z);
PACKAGE REFERENCE
TOP VIEW
AGND
1
FB
2
4
VCC
5
PG
6
IN
11
10
13
14
SW
3
IN
12
SW
SS
EN
FREQ
7
8
9
BST
GND
GND
EXPOSED PAD
ON BACKSIDE
Part Number***
Package
MPQ8612GL-12
QFN14 (3x4mm)
***For Tape & Reel, add suffix –Z (eg. MPQ8612GL–12–Z)
TOP VIEW
EN
4
VCC
5
PG
6
IN
IN
13
12
11
14
13
12
11
15
16
17
7
8
9
10
BST
GND
GND
GND
EXPOSED PAD
ON BACKSIDE
AGND
1
FB
2
SS
3
EN
4
VCC
5
PG
6
15
17
16
SW
3
IN
14
SW
SS
FREQ
SW
2
IN
SW
FB
IN
SW
1
IN
SW
AGND
TOP VIEW
FREQ
7
8
9
10
BST
GND
GND
GND
EXPOSED PAD
ON BACKSIDE
Part Number****
Package
Part Number*****
Package
MPQ8612GR-16
QFN17 (4x4mm)
MPQ8612GR-20
QFN17 (4x4mm)
****For Tape & Reel, add suffix –Z (eg. MPQ8612GR-16–Z)
*****For Tape & Reel, add suffix –Z (eg. MPQ8612GR-20–Z)
MPQ8612 Rev. 1.11
www.MonolithicPower.com
10/22/2013
MPS Proprietary Information. Patent Protected. Unauthorized Photocopy and Duplication Prohibited.
© 2013 MPS. All Rights Reserved.
2
MPQ8612 ― 12A/16A/20A, 6V, SYNCHRONOUS STEP-DOWN CONVERTER
ABSOLUTE MAXIMUM RATINGS (1)
Supply Voltage VIN ...................................... 6.5V
VSW ........................................-0.3V to VIN + 0.3V
VSW (30ns)...................................-3V to VIN + 3V
VIN -VSW .................................-0.3V to VIN + 0.3V
VIN -VSW (30ns) ............................-3V to VIN + 3V
VBST ...................................................... VSW + 6V
All Other Pins ..................................-0.3V to +6V
(2)
Continuous Power Dissipation (TA=+25°) ……
QFN(3x4mm)…………………...……………2.6W
QFN(4x4mm)…………………...……………2.8W
Junction Temperature ...............................150°C
Lead Temperature ....................................260°C
Storage Temperature............... -65°C to +150°C
Recommended Operating Conditions
Thermal Resistance
(4)
θJA
θJC
QFN (3x4mm) ......................... 48 ...... 10... °C/W
QFN (4x4mm) ......................... 44 ....... 9.... °C/W
Notes:
1) Exceeding these ratings may damage the device.
2) The maximum allowable power dissipation is a function of the
maximum junction temperature TJ(MAX), the junction-toambient thermal resistance θJA, and the ambient temperature
TA. The maximum allowable continuous power dissipation at
any ambient temperature is calculated by PD(MAX)=(TJ(MAX)TA)/θJA. Exceeding the maximum allowable power dissipation
will cause excessive die temperature, and the regulator will go
into thermal shutdown. Internal thermal shutdown circuitry
protects the device from permanent damage.
3) The device is not guaranteed to function outside of its
operating conditions.
4) Measured on JESD51-7, 4-layer PCB.
(3)
Supply Voltage VIN ................................3V to 6V
Output Voltage VOUT ....................0.608V to 4.5V
Operating Junction Temp. (TJ). -40°C to +125°C
MPQ8612 Rev. 1.11
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10/22/2013
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© 2013 MPS. All Rights Reserved.
3
MPQ8612 ― 12A/16A/20A, 6V, SYNCHRONOUS STEP-DOWN CONVERTER
ELECTRICAL CHARACTERISTICS
VIN = 5V, TJ = -40 to +125°C, unless otherwise noted.
Parameters
Supply Current
Supply Current (Shutdown)
Supply Current (Quiescent)
Symbol
IIN
IIN
Condition
Typ
Max
Units
0.001
2
μA
850
1100
1300
μA
600
1000
1300
μA
MPQ8612-12, TJ =25°C
10
18
MPQ8612-16, TJ =25°C
7.4
13
MPQ8612-20, TJ =25°C
6.6
12
MPQ8612-12, TJ =25°C
7.8
10
MPQ8612-16, TJ =25°C
5.5
11
MPQ8612-20, TJ =25°C
4.6
9.5
0.001
5
VEN = 0V
VEN = 2V, VFB = 1V,
MPQ8612-12
VEN = 2V, VFB = 1V,
MPQ8612-16,
MPQ8612-20
Min
MOSFET
High-side Switch On Resistance
Low-side Switch On Resistance
Switch Leakage
HSRDS-ON
LSRDS-ON
SWLKG
VEN = 0V, VSW = 0V or 5V,
TJ =25°C
mΩ
mΩ
μA
Current Limit
High-side Current Limit
ILIMIT
MPQ8612-12
17
21
26
MPQ8612-16
23
28
33
MPQ8612-20
29
35
41
A
Timer
One-Shot On Time
Minimum Off Time
tON
tOFF
Fold back Timer(5)
tFOLDBACK
Over-voltage and Under-voltage Protection
OVP Threshold
VOVP1
OVP Delay(5)
tOVP
(5)
UVP Threshold
VUVP
RFREQ=82kΩ,VOUT=1.2V,
MPQ8612-12
RFREQ=82kΩ,VOUT=1.2V,
MPQ8612-16,
MPQ8612-20
MPQ8612-12
MPQ8612-16,
MPQ8612-20
OCP Happens
170
ns
200
ns
30
75
150
ns
30
110
160
ns
2.5
110
120
1
50
MPQ8612 Rev. 1.11
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10/22/2013
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© 2013 MPS. All Rights Reserved.
μs
130
%VREF
μs
%VREF
4
MPQ8612 ― 12A/16A/20A, 6V, SYNCHRONOUS STEP-DOWN CONVERTER
ELECTRICAL CHARACTERISTICS (continued)
VIN = 5V, TJ = -40 to +125°C, unless otherwise noted.
Parameters
Symbol
Condition
Min
Typ
Max
Units
TJ = -20°C to +85°C,
MPQ8612-12
602
608
614
TJ = -20°C to +85°C,
MPQ8612-16,
MPQ8612-20
604
610
616
TJ = -40°C to +125°C,
MPQ8612-12
599
608
617
601
610
619
5.5
0.001
7.5
50
9
nA
μA
1.8
V
mV
Reference And Soft Start
Reference Voltage
Feedback Current
Soft Start Charging Current
Enable And UVLO
Enable Rising Threshold
Enable Hysteresis
Enable Input Current
VCC UVLO
VCC Under Voltage Lockout
Threshold Rising
VCC Under Voltage Lockout
Threshold Hysteresis
Power Good
Power Good Rising Threshold
Power Good Falling Threshold
Power Good Deglitch Timer
Power Good Sink Current
Capability
Power Good Leakage Current
Thermal Protection
Thermal Shutdown
Thermal Shutdown Hysteresis
VREF
IFB
ISS
TJ = -40°C to +125°C,
MPQ8612-16,
MPQ8612-20
VFB = 608mV
VSS=0V
ENVth-Hi
ENVth-Hy
IEN
mV
1.4
VEN = 2V
VEN = 0V
VCCVth
1
890
1.5
0.001
2
2.3
2.8
2.95
300
VCCHYS
PGVth-Hi
PGVth-Lo
PGTd
TSS=1ms,
VPG
IPG_LEAK
TSD
84
63
V
mV
96
73
2.2
%VREF
%VREF
ms
Sink 4mA
0.4
V
VPG = 3.3V
50
nA
Note 5
150
90
70
1.6
μA
160
25
°C
°C
Note:
5) Guaranteed by design.
MPQ8612 Rev. 1.11
www.MonolithicPower.com
10/22/2013
MPS Proprietary Information. Patent Protected. Unauthorized Photocopy and Duplication Prohibited.
© 2013 MPS. All Rights Reserved.
5
MPQ8612 ― 12A/16A/20A, 6V, SYNCHRONOUS STEP-DOWN CONVERTER
TYPICAL CHARACTERISTICS
Performance waveforms are tested on the evaluation board of the Design Example section.
VIN=5V, VOUT=1.2V, L=1.0µH, TA=+25°C, unless otherwise noted.
0.8
1150
18
16
0.7
14
0.6
12
1100
0.5
10
0.4
8
0.3
6
1050
0.2
4
0.1
2
0
-50 -25
0
25 50 75 100 125 150
1000
-50 -25
8
21.50
7
21.40
0
25 50 75 100 125 150
21.20
28
21.10
27.8
4
21.00
3
20.90
27.2
20.60
0
50
100
150
20.50
-50 -25
27
0
-40
25 50 75 100 125 150
35..8
162
1470
35.6
160
1469
35
34.8
1465
152
1464
34.4
146
-50 -25 0
-40
0
25
85
125
125
1463
150
148
85
1466
154
34.6
25
1467
156
35.2
0
1468
158
35.4
150
27.4
20.70
0
-50
100
27.6
20.80
1
50
28.2
5
2
0
28.4
21.30
6
0
-50
1462
25 50 75 100 125 150
1461
1460
-50 -25
0
25 50 75 100 125 150
MPQ8612 Rev. 1.11
www.MonolithicPower.com
10/22/2013
MPS Proprietary Information. Patent Protected. Unauthorized Photocopy and Duplication Prohibited.
© 2013 MPS. All Rights Reserved.
6
MPQ8612 ― 12A/16A/20A, 6V, SYNCHRONOUS STEP-DOWN CONVERTER
TYPICAL CHARACTERISTICS (continued)
Performance waveforms are tested on the evaluation board of the Design Example section.
VIN=5V, VOUT=1.2V, L=1.0µH, TA=+25°C, unless otherwise noted.
Reference Voltage vs.
Temperature
OVP Threshold vs.
Temperature
615
614
613
2.90
122.0
2.85
610
2.70
MPQ8612-20
120.5
608
0
50
2.65
120.0
MPQ8612-12
100
150
EN Threshold vs.
Temperature
25 50 75 100 125 150
2.55
-50 -25 0
25 50 75 100 125 150
Soft-Start/Shutdown Current
vs. Temperature
7.40
1.60
7.35
EN Rising Threshold
VCC Falling Threshold
2.60
119.5
-50 -25 0
1.80
7.30
7.25
1.20
7.20
1.00
7.15
0.80
0.60
VCC Rising Threshold
121.0
MPQ8612-16
609
1.40
2.80
2.75
611
606
-50
122.5
121.5
612
607
VCC UVLO Threshold vs.
Temperature
7.10
EN Falling Threshold
7.05
0.40
7.00
0.20
6.95
0.00
-50 -25 0
25 50 75 100 125 150
6.90
-50
0
50
100
150
MPQ8612 Rev. 1.11
www.MonolithicPower.com
10/22/2013
MPS Proprietary Information. Patent Protected. Unauthorized Photocopy and Duplication Prohibited.
© 2013 MPS. All Rights Reserved.
7
MPQ8612 ― 12A/16A/20A, 6V, SYNCHRONOUS STEP-DOWN CONVERTER
TYPICAL PERFORMANCE CHARACTERISTICS (continued)
Performance waveforms are tested on the evaluation board of the Design Example section.
MPQ8612-12, VIN=5V, VOUT=1.2V, L=1.0µH, TA=+25°C, unless otherwise noted.
100
100
100
95 VIN=3.3V
VIN=3.3V
95
90
85
85
80
VIN=4.2V
75
70
VIN=4.2V
80
75
VIN=5V
65
75
VIN=5V
50
0.01
0.1
1
10
100
60
0.01
0.1
1
10
100
65
0.01
80
70
65
1
10
100
75
0.01
OUTPUT CURRENT (A)
100
VIN=3.3V
95
90
VIN=4.2V
70
65
65
VIN=6V
0.1
1
10
OUTPUT CURRENT (A)
100
10
100
100
75
VIN=5V
1
OUTPUT CURRENT (A)
VIN=3.3V
95
60
0.01
VIN=3.3V
90
85
80
75
55
0.01
100
85
80
60
10
90
85
70
1
55
VIN=6V
50
0.01
0.1
OUTPUT CURRENT (A)
100
95
0.1
VIN=5V
60
VIN=6V
VIN=6V
VIN=4.2V
75
VIN=5V
85
80
0.1
100
85
VIN=4.2V
75
70
10
90
90
VIN=5V
1
100
95 VIN=3.3V
95
VIN=4.2V
0.1
OUTPUT CURRENT (A)
100
90
85
VIN=6V
60
0.01
OUTPUT CURRENT (A)
VIN=3.3V
80
65
VIN=6V
OUTPUT CURRENT (A)
100
VIN=5V
70
65
VIN=6V
55
VIN=4.2V
80
70
60
VIN=3.3V
90
90
85
95
95
VIN=4.2V
VIN=5V
75
70
VIN=6V
0.1
1
10
OUTPUT CURRENT (A)
VIN=4.2V
80
100
65
0.01
VIN=5V
VIN=6V
0.1
1
10
100
OUTPUT CURRENT (A)
MPQ8612 Rev. 1.11
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10/22/2013
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© 2013 MPS. All Rights Reserved.
8
MPQ8612 ― 12A/16A/20A, 6V, SYNCHRONOUS STEP-DOWN CONVERTER
TYPICAL PERFORMANCE CHARACTERISTICS (continued)
Performance waveforms are tested on the evaluation board of the Design Example section.
MPQ8612-12, VIN=5V, VOUT=1.2V, L=1.0µH, TA=+25°C, unless otherwise noted.
100
1.00
0.6
0.4
95
0.50
0.2
90
0.00
0
85
-0.2
-0.50
80
75
0.01
-0.4
0.1
1
10
100
-1.00
3
1200
650
1000
630
4
5
6
2
4
6
8
10
12
2
4
6
8
10
12
700
600
500
800
610
400
590
300
600
400
200
570
200
0
200
-0.6
0
400
600
800
1000 1200
550
3
100
3.5
4
4.5
5
5.5
6
0
0
MPQ8612 Rev. 1.11
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10/22/2013
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9
MPQ8612 ― 12A/16A/20A, 6V, SYNCHRONOUS STEP-DOWN CONVERTER
TYPICAL PERFORMANCE CHARACTERISTICS (continued)
Performance waveforms are tested on the evaluation board of the Design Example section.
MPQ8612GL-12, VIN=5V, VOUT=1.2V, L=1.0µH, TA=+25°C, unless otherwise noted.
Dead Time (on)
Dead Time Off
Input/Output Voltage Rippl
IOUT =12A
IOUT =12A
IOUT = 0A
VOUT
AC Coupled
20mV/div.
VIN
AC Coupled
10mV/div.
VSW
1V/div.
VSW
200mV/div.
VSW
5V/div.
IL
2.5A/div.
Input/Output Voltage Ripple
Input/Output Voltage Ripple
IOUT = 0.4A
IOUT = 12A
Power Good Through Vin
Start-Up
IOUT = 12A
VOUT
AC Coupled
10mV/div.
VIN
AC Coupled
10mV/div.
VOUT
AC Coupled
10mV/div.
VSW
5V/div.
VSW
5V/div.
VOUT
1V/div.
VIN
AC Coupled
100mV/div.
IL
1A/div.
VIN
2V/div.
VPG
1V/div.
IL
10A/div.
Power Good Through Vin
Shutdown
Power Good Through EN
Start-Up
Power Good Through EN
Shutdown
IOUT = 12A
IOUT = 12A
IOUT = 12A
VOUT
1V/div.
VOUT
1V/div.
VIN
2V/div.
VEN
5V/div.
VEN
5V/div.
VPG
2V/div.
VPG
5V/div.
VPG
5V/div.
VOUT
1V/div.
MPQ8612 Rev. 1.11
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10/22/2013
MPS Proprietary Information. Patent Protected. Unauthorized Photocopy and Duplication Prohibited.
© 2013 MPS. All Rights Reserved.
10
MPQ8612 ― 12A/16A/20A, 6V, SYNCHRONOUS STEP-DOWN CONVERTER
TYPICAL PERFORMANCE CHARACTERISTICS (continued)
Performance waveforms are tested on the evaluation board of the Design Example section.
MPQ8612GL-12, VIN=5V, VOUT=1.2V, L=1.0µH, TA=+25°C, unless otherwise noted.
Start-Up Through Vin
Start-Up Through Vin
Shutdown Through Vin
IOUT = 0A
IOUT = 12A
IOUT = 0A
VOUT
1V/div.
VOUT
1V/div.
VOUT
1V/div.
VIN
5V/div.
VSW
5V/div.
VIN
5V/div.
VSW
5V/div.
VIN
5V/div.
IL
1A/div.
IL
10A/div.
VSW
2V/div.
IL
1A/div.
Shutdown Through Vin
Start-Up Through EN
Start-Up Through EN
IOUT = 12A
IOUT = 0A
IOUT = 12A
VOUT
1V/div.
VOUT
1V/div.
VOUT
1V/div.
VIN
5V/div.
VSW
5V/div.
VEN
5V/div.
VIN
5V/div.
VSW
5V/div.
IL
2.5A/div.
VSW
5V/div.
IL
10A/div.
IL
10A/div.
Shutdown Through EN
Shutdown Through EN
IOUT = 0A
IOUT = 12A
VOUT
1V/div.
VOUT
1V/div.
VEN
5V/div.
VEN
5V/div.
VSW
5V/div.
VSW
5V/div.
IL
1A/div.
IL
10A/div.
VOUT
AC Coupled
200mV/div.
IL
5A/div.
MPQ8612 Rev. 1.11
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10/22/2013
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11
MPQ8612 ― 12A/16A/20A, 6V, SYNCHRONOUS STEP-DOWN CONVERTER
TYPICAL PERFORMANCE CHARACTERISTICS (continued)
Performance waveforms are tested on the evaluation board of the Design Example section.
MPQ8612GL-12, VIN=5V, VOUT=1.2V, L=1.0µH, TA=+25°C, unless otherwise noted.
Short Circuit Protection
VOUT
1V/div.
VSW
5V/div.
IL
10A/div.
Thermal Shutdown
Thermal Recovery
IOUT = 12A
IOUT = 12A
VOUT
1V/div.
VOUT
1V/div.
VSW
5V/div.
VSW
5V/div.
IL
10A/div.
IL
10A/div.
MPQ8612 Rev. 1.11
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10/22/2013
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12
MPQ8612 ― 12A/16A/20A, 6V, SYNCHRONOUS STEP-DOWN CONVERTER
PIN FUNCTIONS
MPQ8612GL-12
PIN #
Name
Description
1
AGND
2
FB
3
SS
4
EN
5
VCC
6
PG
7
BST
8-9
GND
10-11
IN
12
FREQ
13-14
SW
Analog ground.
Feedback. An external resistor divider from the output to GND, tapped to the FB pin, sets
the output voltage. It is recommended to place the resistor divider as close to FB pin as
possible. Vias should be avoided on the FB traces.
Soft Start. Connect on external capacitor to program the soft start time for the switch
mode regulator.
Enable pin. Pull this pin higher than 1.25V to enable the chip. For automatic start-up,
connect EN pin to VIN with 100KΩ resistor.
Can be used to set the on/off threshold (adjust UVLO) with two additional resistors.
Supply Voltage for driver and control circuits. Decouple with a minimum 4.7µF ceramic
capacitor as close to the pin as possible. X7R or X5R grade dielectric ceramic capacitors
are recommended for their stable temperature characteristics.
Power good output, and it is high if the output voltage is higher than 90% of the nominal
voltage. There is a delay from FB ≥ 90% to PGOOD goes high.
Bootstrap. A capacitor connected between SW and BS pins is required to form a floating
supply across the high-side switch driver.
System Ground. This pin is the reference ground of the regulated output voltage. For this
reason care must be taken in PCB layout.
Supply Voltage. The IN pin supplies power for internal MOSFET and regulator. The
MPQ8612 operate from a +3V to +6V input rail. An input capacitor is needed to decouple
the input rail. Use wide PCB traces and multiple vias to make the connection.
Frequency set during CCM operation. A resistor connected between FREQ and IN is
required to set the switching frequency. The ON time is determined by the input voltage
and the resistor connected to the FREQ pin. IN connect through a resistor is used for line
feed-forward and makes the frequency basically constant during input voltage’s variation.
An optional 1nF decoupling capacitor can be added to improve any switching frequency
jitter that may be present.
Switch Output. Connect this pin to the inductor and bootstrap capacitor. This pin is driven
up to the VIN voltage by the high-side switch during the on-time of the PWM duty cycle.
The inductor current drives the SW pin negative during the off-time. The on-resistance of
the low-side switch and the internal Schottky diode fixes the negative voltage. Use wide
PCB traces to make the connection.
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MPQ8612 ― 12A/16A/20A, 6V, SYNCHRONOUS STEP-DOWN CONVERTER
PIN FUNCTIONS (continued)
MPQ8612GR-16, MPQ8612GR-20
PIN #
1
Name
AGND
2
FB
3
SS
4
EN
5
VCC
6
PG
7
BST
8-10
GND
11-13
IN
14
FREQ
15-17
SW
Description
Analog ground.
Feedback. An external resistor divider from the output to GND, tapped to the FB pin, sets
the output voltage. It is recommended to place the resistor divider as close to FB pin as
possible. Vias should be avoided on the FB traces.
Soft Start. Connect on external capacitor to program the soft start time for the switch
mode regulator.
Enable pin. Pull this pin higher than 1.25V to enable the chip. For automatic start-up,
connect EN pin to VIN with 100KΩ resistor.
Can be used to set the on/off threshold (adjust UVLO) with two additional resistors.
Supply Voltage for driver and control circuits. Decouple with a minimum 4.7µF ceramic
capacitor as close to the pin as possible. X7R or X5R grade dielectric ceramic capacitors
are recommended for their stable temperature characteristics.
Power good output, and it is high if the output voltage is higher than 90% of the nominal
voltage. There is a delay from FB ≥ 90% to PGOOD goes high.
Bootstrap. A capacitor connected between SW and BS pins is required to form a floating
supply across the high-side switch driver.
System Ground. This pin is the reference ground of the regulated output voltage. For this
reason care must be taken in PCB layout.
Supply Voltage. The IN pin supplies power for internal MOSFET and regulator. The
MPQ8612 operate from a +3V to +6V input rail. An input capacitor is needed to decouple
the input rail. Use wide PCB traces and multiple vias to make the connection.
Frequency set during CCM operation. A resistor connected between FREQ and IN is
required to set the switching frequency. The ON time is determined by the input voltage
and the resistor connected to the FREQ pin. IN connect through a resistor is used for line
feed-forward and makes the frequency basically constant during input voltage’s variation.
An optional 1nF decoupling capacitor can be added to improve any switching frequency
jitter that may be present.
Switch Output. Connect this pin to the inductor and bootstrap capacitor. This pin is driven
up to the VIN voltage by the high-side switch during the on-time of the PWM duty cycle.
The inductor current drives the SW pin negative during the off-time. The on-resistance of
the low-side switch and the internal Schottky diode fixes the negative voltage. Use wide
PCB traces to make the connection.
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MPQ8612 ― 12A/16A/20A, 6V, SYNCHRONOUS STEP-DOWN CONVERTER
BLOCK DIAGRAM
IN
FREQ
Current Sense
Amplifer
RSEN
Over-Current OC
Timer
VCC
ILIM
EN
REFERENCE
1MEG
HS Limit
Comparator
Refresh
Timer
OFF
Timer
xS Q
0.3V
0.75V
0.608V
BST
BSTREG
HS
Driver
PWM
HS-FET
xR
LOGIC
SS
SOFT
START/STOP
START
FB
Loop
Comparator
SW
VCC
ON
Timer
LS
Driver
LS-FET
Current
Modulator
PG
UV
PGOOD
Comparator
UV Detect
Comparator
GND
AGND
OV
OV Detect
Comparator
Figure 1—Functional Block Diagram
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MPQ8612 ― 12A/16A/20A, 6V, SYNCHRONOUS STEP-DOWN CONVERTER
OPERATION
PWM Operation
The MPQ8612 is fully integrated synchronous
rectified step-down switch mode converter.
Constant-on-time (COT) control is employed to
provide fast transient response and easy loop
stabilization. At the beginning of each cycle, the
high-side MOSFET (HS-FET) is turned ON when
the feedback voltage (VFB) is below the reference
voltage (VREF), which indicates insufficient output
voltage. The ON period is determined by the
input voltage and the frequency-set resistor as
follows:
t ON (ns) =
4.8 × R FREQ (kΩ )
VIN ( V ) − 0.49
(1)
After the ON period elapses, the HS-FET is
turned off, or becomes OFF state. It is turned ON
again when VFB drops below VREF. By repeating
operation this way, the converter regulates the
output voltage. The integrated low-side MOSFET
(LS-FET) is turned on when the HS-FET is in its
OFF state to minimize the conduction loss. There
will be a dead short between input and GND if
both HS-FET and LS-FET are turned on at the
same time. It’s called shoot-through. In order to
avoid shoot-through, a dead-time (DT) is
internally generated between HS-FET off and LSFET on, or LS-FET off and HS-FET on.
Heavy-Load Operation
below VREF, HS-MOSFET is turned on for a fixed
interval which is determined by one- shot ontimer as equation 1 shown. When the HSMOSFET is turned off, the LS-MOSFET is turned
on until next period.
In CCM mode operation, the switching frequency
is fairly constant and it is called PWM mode.
Light-Load Operation
With the load decreasing, the inductor current
decreases too. When the inductor current
touches zero, the operation is transited from
continuous-conduction-mode
(CCM)
to
discontinuous-conduction-mode (DCM).
The light load operation is shown in Figure 3.
When VFB is below VREF, HS-MOSFET is turned
on for a fixed interval which is determined by
one- shot on-timer as equation 1 shown. When
the HS-MOSFET is turned off, the LS-MOSFET
is turned on until the inductor current reaches
zero. In DCM operation, the VFB does not reach
VREF when the inductor current is approaching
zero. The driver of LS-FET turns into tri-state
(high Z) whenever the inductor current reaches
zero. A current modulator takes over the control
of LS-FET and limits the inductor current to less
than -1mA. Hence, the output capacitors
discharge slowly to GND through LS-FET. As a
result, the efficiency at light load condition is
greatly improved. At light load condition, the HSFET is not turned ON as frequently as at heavy
load condition. This is called skip mode.
At light load or no load condition, the output
drops very slowly and the MPQ8612 reduce the
switching frequency naturally and then high
efficiency is achieved at light load.
TON is constont
VIN
Figure 2—Heavy Load Operation
When the output current is high and the inductor
current is always above zero amps, it is called
continuous-conduction-mode (CCM). The CCM
mode operation is shown in Figure2. When VFB is
Current Modulator
regulates around
-1mA
VSW
VOUT
IL
IOUT
VFB
VREF
Figure 3—Light Load Operation
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MPQ8612 ― 12A/16A/20A, 6V, SYNCHRONOUS STEP-DOWN CONVERTER
As the output current increases from the light
load condition, the time period within which the
current modulator regulates becomes shorter.
The HS-FET is turned ON more frequently.
Hence, the switching frequency increases
correspondingly. The output current reaches the
critical level when the current modulator time is
zero. The critical level of the output current is
determined as follows:
IOUT =
(VIN − VOUT ) × VOUT
2 × L × fSW × VIN
(2)
It turns into PWM mode once the output current
exceeds the critical level. After that, the switching
frequency stays fairly constant over the output
current range.
Switching Frequency
The selection of switching frequency is a tradeoff
between efficiency and component size. Low
frequency operation increases efficiency by
reducing MOSFET switching losses, but requires
larger inductance and capacitance to maintain
low output voltage ripple.
For MPQ8612 , the on time can be set using
FREQ pin, then the frequency is set in steady
state operation at CCM mode.
Adaptive constant-on-time (COT) control is used
in MPQ8612 and there is no dedicated oscillator
in the IC. Connect FREQ pin to IN pin through
resistor RFREQ and the input voltage is feedforwarded to the one-shot on-time timer through
the resistor RFREQ. When in steady state
operation at CCM, the duty ratio is kept as
VOUT/VIN. Hence the switching frequency is fairly
constant over the input voltage range. The
switching frequency can be set as follows:
fSW (kHz) =
106
4.8 × RFREQ (kΩ) VIN (V)
×
+ tDELAY (ns)
VIN (V) − 0.49
VOUT (V)
(3)
Where TDELAY is the comparator delay. It’s about
40ns.
Generally, the MPQ8612 is set for 300kHz to
1MHz application. It is optimized to operate at
high switching frequency with high efficiency.
High switching frequency makes it possible to
utilize small sized LC filter components to save
system PCB space.
Jitter and FB Ramp Slope
Figure 4 and Figure 5 show jitter occurring in
both PWM mode and skip mode. When there is
noise in the VFB downward slope, the ON time of
HS-FET deviates from its intended location and
produces jitter. It is necessary to understand that
there is a relationship between a system’s
stability and the steepness of the VFB ripple’s
downward slope. The slope steepness of the VFB
ripple dominates in noise immunity. The
magnitude of the VFB ripple doesn’t affect the
noise immunity directly.
Figure 4—Jitter in PWM Mode
VSLOPE2
VFB
VNOISE
VREF
HS Driver
Jitter
Figure 5—Jitter in Skip Mode
Ramp with Large ESR Capacitor
In the case of POSCAP or other types of
capacitor with lager ESR is applied as output
capacitor, the ESR ripple dominates the output
ripple, and the slope on the FB is quite ESR
related. Figure 6 shows an equivalent circuit in
PWM mode with the HS-FET off and without an
external ramp circuit. Turn to application
information section for design steps with large
ESR capacitors.
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MPQ8612 ― 12A/16A/20A, 6V, SYNCHRONOUS STEP-DOWN CONVERTER
SW
L
Where:
Vo
FB
ESR
R1
And the ramp on the VFB can then be estimated
as:
POSCAP
R2
VRAMP =
Figure 6—Simplified Circuit in PWM Mode
without External Ramp Compensation
To realize the stability when no external ramp is
applied, usually the ESR value should be chosen
as follow:
RESR
t SW
t
+ ON
×
π
0.7
2
≥
COUT
(4)
TSW is the switching period.
Ramp with Small ESR Capacitor
When the output capacitors are ceramic ones,
the ESR ripple is not high enough to stabilize the
system, and external ramp compensation is
needed. Skip to application information section
for design steps with small ESR caps.
L
SW
R4
Vo
C4
IR4
IC4
R9
⎛ R1 // R2 ⎞
VIN − VO
× t ON × ⎜
⎟
R 4 × C4
⎝ R1 // R2 + R9 ⎠
(7)
The downward slope of the VFB ripple then
follows:
VSLOPE1 =
− VOUT
VRAMP
=
t off
R 4 × C4
(8)
As can be seen from equation 8, if there is
instability in PWM mode, we can reduce either
R4 or C4. If C4 can not be reduced further due to
limitation from equation 5, then we can only
reduce R4. For a stable PWM operation, the
Vslope1 should be design follow equation 9.
− VSLOPE1
t SW
t
+ ON − RESR × COUT
0.7 × IO × 10−3
×
π
0.7
2
≥
× VOUT +
2 × L × COUT
t sw − t on
(9)
Where Io is the load current.
In skip mode, the downward slope of the VFB
ripple is almost same whether the external ramp
is used or not. Fig.8 shows the simplified circuit
of the skip mode when both the HS-FET and LSFET are off.
R1
Vo
I FB
Ceramic
FB
(6)
IR4 = IC4 + IFB ≈ IC4
FB
R2
R1
Cout
Ro
R2
Figure 7—Simplified Circuit in PWM Mode
with External Ramp Compensation
In PWM mode, an equivalent circuit with HS-FET
off and the use of an external ramp
compensation circuit (R4, C4) is simplified in
Figure 7. The external ramp is derived from the
inductor ripple current. If one chooses C4, R9,
R1 and R2 to meet the following condition:
⎞
1
1 ⎛ R1 × R 2
<
×⎜
+ R9 ⎟
2π × fSW × C4 20 ⎝ R1 + R 2
⎠
(5)
Figure 8—Simplified Circuit in skip Mode
The downward slope of the VFB ripple in skip
mode can be determined as follows:
VSLOPE2 =
− VREF
[(R1 + R2 ) // RO ] × COUT
(10)
Where Ro is the equivalent load resistor.
As described in Fig.5, VSLOPE2 in the skip mode is
lower than that is in the PWM mode, so it is
reasonable that the jitter in the skip mode is
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MPQ8612 ― 12A/16A/20A, 6V, SYNCHRONOUS STEP-DOWN CONVERTER
larger. If one wants a system with less jitter
during ultra light load condition, the values of the
VFB resistors should not be too big, however, that
will decrease the light load efficiency.
Soft Start/Stop
The MPQ8612 employs soft start/stop (SS)
mechanism to ensure smooth output during
power up and power down.
When the EN pin becomes high, an internal
current source (8μA) charges up the SS capacitor
C6. The SS capacitor voltage takes over the REF
voltage to the PWM comparator. The output
voltage smoothly ramps up with the SS voltage.
Once the SS voltage reaches the same level as
the REF voltage, it keeps ramping up while VREF
takes over the PWM comparator. At this point,
the soft start finishes and it enters into steady
state operation.
When the EN pin is pulled to low, the SS CAP
voltage is discharged through an 8uA internal
current source. Once the SS voltage reaches
REF voltage, it takes over the PWM comparator.
The output voltage will decrease smoothly with
SS voltage until zero level. The SS capacitor
value can be determined as follows:
CSS (nF) =
t SS (ms) × ISS (μA)
VREF
(11)
If the output capacitors have large capacitance
value, it’s not recommended to set the SS time
too small. Otherwise, it’s easy to hit the current
limit during SS. A minimum value of 4.7nF should
be used if the output capacitance value is larger
than 330μF.
Pre-Bias Startup
If the output is pre-biased to a certain voltage
during startup, the MPQ8612 will disable the
switching of both high-side and low-side switches
until the voltage on the internal soft-start
capacitor exceeds the sensed output voltage at
the FB pin.
Power Good (PG)
The MPQ8612 has power-good (PG) output. It
can be connected to VCC or other voltage source
through a resistor (e.g. 100k). When the
MPQ8612 is powered on and FB voltage reaches
above 90% of REF voltage, the PG pin is pulled
high.
When the FB voltage drops to 70% of REF
voltage or the part is not powered on, the PG pin
will be pulled low.
Over-Current Protection (OCP)
The MPQ8612 enters over-current protection
mode when the inductor current hits the current
limit, and tries to recover from over-current fault
with hiccup mode. That means in over-current
protection, the chip will disable output power
stage, discharge soft-start capacitor and then
automatically try to soft-start again. If the overcurrent condition still holds after soft-start ends,
the chip repeats this operation cycle till overcurrent disappears and output rises back to
regulation level. The MPQ8612 also operates in
hiccup mode when short circuit happens.
Over/Under –Voltage Protection (OVP/UVP)
The MPQ8612 has non-latching over voltage
protection. It monitors the output voltage through
a resistor divider feedback (FB) voltage to detect
over-voltage on the output. When the FB voltage
is higher than 120% of the REF voltage (0.608V),
the LS-FET will be turned on while the HS-FET
will be off. The LS-FET keeps on until it hits the
negative current limit and turns off for 100ns. If
over voltage condition still holds, the chip repeats
this operation cycle till the FB voltage drops
below 110% of the REF voltage.
When the FB voltage is below 50% of the REF
voltage (0.608V), it is recognized as undervoltage (UV). Usually, UVP accompanies a hit in
current limit and results in OCP.
Configuring the EN Control
The EN pin provides electrical on/off control of
the device. Set EN high to turn on the regulator
and low to turn it off. Do not float this pin.
For automatic start-up, the EN pin can be pulled
up to input voltage through a resistive voltage
divider. Choose the values of the pull-up resistor
(RUP from VIN pin to EN pin) and the pull-down
resistor (RDOWN from EN pin to GND) to
determine the automatic start-up voltage:
VIN−START = 1.4 ×
RUP + RDOWN
RDOWN
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(12)
19
MPQ8612 ― 12A/16A/20A, 6V, SYNCHRONOUS STEP-DOWN CONVERTER
For example, for RUP =100kΩ and RDOWN =51kΩ,
the VIN−START is set at 4.15V.
falling threshold
protection.
To avoid noise, a 10nF ceramic capacitor from
EN to GND is recommended.
The MPQ8612 is disabled when the VCC voltage
falls below its UVLO falling threshold (2.45V). If
an application requires a higher under-voltage
lockout (UVLO), use the EN pin as shown in
Figure 9 to adjust the input voltage UVLO by
using two external resistors. It is recommended
to use the enable resistors to set the UVLO
falling threshold (VSTOP) above 2.8 V. The rising
threshold (VSTART) should be set to provide
enough hysteresis to allow for any input supply
variations.
There is an internal zener diode on the EN pin,
which clamps the EN pin voltage to prevent it
from running away. The maximum pull up current
assuming a worst case 6V internal zener clamp
should be less than 1mA. Therefore, when EN is
driven by an external logic signal, the EN voltage
should be lower than 6V; when EN is connected
with VIN through a pull-up resistor or a resistive
voltage divider, the resistance selection should
ensure the maximum pull up current less than
1mA.
If using a resistive voltage divider and VIN higher
than 6V, the allowed minimum pull-up resistor
RUP should meet the following equation:
VIN (V) − 6
6
−
< 1(mA)
RUP (kΩ) RDOWN (kΩ)
VIN (V) − 6
1(mA)
This
is
non-latch
IN
VCC
R UP
MPQ8612
EN Comparator
EN
(13)
RDOWN
As a result, when just the pull-up resistor RUP is
applied, the VIN−START is determined by input
UVLO. The value of RUP can be get as:
RUP (kΩ) >
voltage.
(14)
A typical pull-up resistor is 100kΩ.
UVLO protection
The MPQ8612 has under-voltage lock-out
protection (UVLO). When the VCC voltage is
higher than the UVLO rising threshold voltage,
the MPQ8612 will be powered up. It shuts off
when the VCC voltage is lower than the UVLO
Figure 9—Adjustable UVLO
Thermal Shutdown
Thermal shutdown is employed in the MPQ8612.
The junction temperature of the IC is internally
monitored. If the junction temperature exceeds
the threshold value (minimum 150ºC), the
converter shuts off. This is a non-latch protection.
There is about 25ºC hysteresis. Once the
junction temperature drops to about 125ºC, it
initiates a soft startup.
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MPQ8612 ― 12A/16A/20A, 6V, SYNCHRONOUS STEP-DOWN CONVERTER
APPLICATION INFORMATION
Setting the Output Voltage-Large ESR Caps
For applications that electrolytic capacitor or POS
capacitor with a controlled output of ESR is set
as output capacitors. The output voltage is set by
feedback resistors R1 and R2. As figure 10
shows.
SW
Vo
L
FB
R1 =
ESR
R1
in Figure 11. The VRAMP can be calculated as
shown in equation 7. R2 should be chosen
reasonably, a small R2 will lead to considerable
quiescent current loss while too large R2 makes
the FB noise sensitive. It is recommended to
choose a value within 5kΩ-100kΩ for R2, using a
comparatively larger R2 when VOUT is low, and a
smaller R2 when VOUT is high. And the value of
R1 then is determined as follow:
VOUT − VFB( AVG)
POSCAP
R2
Figure 10—Simplified Circuit of POS Capacitor
First, choose a value for R2. R2 should be
chosen reasonably, a small R2 will lead to
considerable quiescent current loss while too
large R2 makes the FB noise sensitive. It is
recommended to choose a value within 5kΩ100kΩ for R2, using a comparatively larger R2
when VOUT is low, and a smaller R2 when VOUT is
high. Then R1 is determined as follow with the
output ripple considered:
R1 =
VOUT
1
− × ΔVOUT − VREF
2
× R2
VREF
(15)
ΔVOUT is the output ripple determined by equation
21.
FB
Vo
L
R4
C4
R9
R1
Ceramic
R2
Figure 11—Simplified Circuit of Ceramic
Capacitor
When low ESR ceramic capacitor is used in the
output, an external voltage ramp should be
added to FB through resistor R4 and capacitor
C4.The output voltage is influenced by ramp
voltage VRAMP besides resistor divider as shown
R2
−
R 4 + R9
(16)
The VFB(AVG) is the average value on the FB.
VFB(AVG) varies with the Vin, Vo, and load
condition, etc.. Its value on the skip mode would
be lower than that of the PWM mode, which
means the load regulation is strictly related to the
VFB(AVG). Also the line regulation is related to the
VFB(AVG) ,if one wants to gets a better load or line
regulation, a lower VRAMP is suggested once it
meets equation 9.
For PWM operation, VFB(AVG) value can be
deduced from equation 17.
VFB( AVG) = VREF +
R1 // R2
1
× VRAMP ×
2
R1 // R2 + R9
(17)
Usually, R9 is set to 0Ω, and it can also be set
following equation 18 for a better noise immunity.
It should be set to be 5 timers smaller than
R1//R2 to minimize its influence on Vramp.
R9 ≤
Setting the Output Voltage-Small ESR Caps
SW
R2
VFB( AVG)
1 R1 × R2
×
10 R1 + R2
(18)
Using equation 16 and 17 to calculate the output
voltage can be complicated. To simplify the
calculation of R1 in equation 16, a DC-blocking
capacitor Cdc can be added to filter the DC
influence from R4 and R9. Figure 12 shows a
simplified
circuit
with
external
ramp
compensation and a DC-blocking capacitor. With
this capacitor, R1 can easily be obtained by
using equation 19 for PWM mode operation.
R1 =
1
× VRAMP
2
× R2
1
+ × VRAMP
2
VOUT − VREF −
VREF
(19)
Cdc is suggested to be at least 10 times larger
than C4 for better DC blocking performance, and
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MPQ8612 ― 12A/16A/20A, 6V, SYNCHRONOUS STEP-DOWN CONVERTER
should be not larger than 0.47uF considering
start up performance. In case one wants to use
larger
Cdc
for
a
better
FB
noise
immunity,combined with reduced R1 and R2 to
limit the Cdc in a reasonable value without
affecting the system start up. Be noted that even
when the Cdc is applied, the load and line
regulation are still Vramp related.
SW
FB
L
R4
Vo
C4
ΔVIN =
Ceramic
The worst-case condition occurs at VIN = 2VOUT,
where:
ΔVIN =
ΔVOUT =
Figure 12—Simplified Circuit of Ceramic
Capacitor with DC blocking capacitor
Input Capacitor
The input current to the step-down converter is
discontinuous. Therefore, a capacitor is required
to supply the AC current to the step-down
converter while maintaining the DC input voltage.
Ceramic capacitors are recommended for best
performance. In the layout, it’s recommended to
put the input capacitors as close to the IN pin as
possible.
The capacitance varies significantly over
temperature. Capacitors with X5R and X7R
ceramic dielectrics are recommended because
they are fairly stable over temperature.
The capacitors must also have a ripple current
rating greater than the maximum input ripple
current of the converter. The input ripple current
can be estimated as follows:
VOUT
V
× (1 − OUT )
VIN
VIN
(20)
The worst-case condition occurs at VIN = 2VOUT,
where:
ICIN =
IOUT
2
(22)
I
1
× OUT
4 fSW × CIN
(23)
The output capacitor is required to maintain the
DC output voltage. Ceramic or POSCAP
capacitors are recommended. The output voltage
ripple can be estimated as:
R2
ICIN = IOUT ×
IOUT
V
V
× OUT × (1 − OUT )
fSW × CIN VIN
VIN
Output Capacitor
R1
Cdc
The input voltage ripple can be estimated as
follows:
(21)
For simplification, choose the input capacitor
whose RMS current rating is greater than half of
the maximum load current.
The input capacitance value determines the input
voltage ripple of the converter. If there is input
voltage ripple requirement in the system design,
choose the input capacitor that meets the
specification
VOUT
V
1
× (1 − OUT ) × (RESR +
) (24)
fSW × L
VIN
8 × fSW × COUT
In the case of ceramic capacitors, the impedance
at the switching frequency is dominated by the
capacitance. The output voltage ripple is mainly
caused by the capacitance. For simplification,
the output voltage ripple can be estimated as:
ΔVOUT =
VOUT
V
× (1 − OUT )
VIN
8 × fSW 2 × L × COUT
(25)
The output voltage ripple caused by ESR is very
small. Therefore, an external ramp is needed to
stabilize the system. The external ramp can be
generated through resistor R4 and capacitor C4
following equation 5, 8 and 9.
In the case of POSCAP capacitors, the ESR
dominates the impedance at the switching
frequency. The ramp voltage generated from the
ESR is high enough to stabilize the system.
Therefore, an external ramp is not needed. A
minimum ESR value around 12mΩ is required to
ensure stable operation of the converter. For
simplification, the output ripple can be
approximated as:
ΔVOUT =
VOUT
V
× (1 − OUT ) × RESR
fSW × L
VIN
(26)
Inductor
The inductor is required to supply constant
current to the output load while being driven by
the switching input voltage. A larger value
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MPQ8612 ― 12A/16A/20A, 6V, SYNCHRONOUS STEP-DOWN CONVERTER
inductor will result in less ripple current and
lower output ripple voltage. However, a larger
value inductor will have a larger physical size,
higher series resistance, and/or lower saturation
current. A good rule for determining the inductor
value is to allow the peak-to-peak ripple current
in the inductor to be approximately 10~30% of
the maximum output current. Also, make sure
that the peak inductor current is below the
current limit of the device. The inductance value
can be calculated as:
L=
VOUT
V
× (1 − OUT )
fSW × ΔIL
VIN
Where ΔIL is the peak-to-peak inductor ripple
current.
Choose an inductor that will not saturate under
the maximum inductor peak current. The peak
inductor current can be calculated as:
ILP = IOUT +
VOUT
V
× (1 − OUT )
2 × fSW × L
VIN
(28)
The inductors listed in Table 1 are highly
recommended for the high efficiency they can
provide.
(27)
Table 1—Inductor Selection Guide
Part Number
Manufacturer
Inductance
(µH)
DCR
(mΩ)
Current
Rating (A)
Dimensions
L x W x H (mm3)
FDU1250C-R50M
FDU1250C-R56M
FDU1250C-R75M
FDU1250C-1R0M
TOKO
TOKO
TOKO
TOKO
0.50
0.56
0.75
1.0
1.3
1.6
1.7
2.2
46.3
42.6
32.7
31.3
13.3 x 12.1 x5
13.3 x 12.1 x5
13.3 x 12.1 x5
13.3 x 12.1 x5
Typical Design Parameter Tables
The following tables include recommended
component values for typical output voltages
(1.0V, 1.2V, 1.8V, 3.3V) and switching
frequencies (600kHz, 800kHz, and 1MHz). Refer
to Tables 2-4 for design cases without external
ramp compensation and Tables 5-7 for design
cases with external ramp compensation.
External ramp is not needed when high-ESR
capacitors, such as electrolytic or POSCAPs are
used. External ramp is needed when low-ESR
capacitors, such as ceramic capacitors are used.
For cases not listed in this datasheet, a calculator
in excel spreadsheet can also be requested
through a local sales representative to assist with
the calculation.
Table 2—COUT-Poscap, 600kHz, 5VIN
VOUT
(V)
1.0
1.2
L
(μH)
1.0
1.0
R1
(kΩ)
19.8
29.4
R2
(kΩ)
30
30
R7
(kΩ)
300
365
1.5
1.0
29.4
20
453
1.8
1.0
39.2
20
549
3.3
1.0
44.2
10
1000
Switching
Frequency
(kHz)
1000
800-1000
600-800
600
Table 3—COUT-Poscap, 800kHz, 5VIN
VOUT
(V)
1.0
L
(μH)
0.75
R1
(kΩ)
20
R2
(kΩ)
30
R7
(kΩ)
210
1.2
0.75
20
20
270
1.5
0.75
30
20
330
1.8
3.3
0.75
0.75
39
44.2
20
10
499
750
VOUT
(V)
1.0
1.2
1.5
1.8
3.3
VOUT
(V)
1.0
1.2
1.5
1.8
3.3
Table 5—COUT-Ceramic, 600kHz, 5VIN
L
(μH)
1.0
1.0
1.0
1.0
1.0
R1
(kΩ)
21
33
51
45
62
R2
(kΩ)
30
30
30
20
10
R4
(kΩ)
240
220
330
270
160
C4
(pF)
470
470
390
470
680
R7
(kΩ)
309
365
464
549
953
Table 6—COUT-Ceramic, 800kHz, 5VIN
L
(μH)
0.75
0.75
0.75
0.75
0.75
R1
(kΩ)
21
34
34
47.5
57.6
R2
(kΩ)
30
30
20
20
10
R4
(kΩ)
200
200
220
225
200
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C4
(pF)
470
470
470
470
560
R7
(kΩ)
226
270
324
402
750
23
MPQ8612 ― 12A/16A/20A, 6V, SYNCHRONOUS STEP-DOWN CONVERTER
TYPICAL APPLICATION
VIN
C1B
C1A
22uF
22uF
C1C
22uF
C1D
C1E
0.1uF 22uF
R6
R8
100K
360K
FREQ
C7
1nF
10
R3
BST
IN
R7
0
C3
1uF
L1
1uH
SW
VOUT
R1
MPQ8612GL-12
+
29.4K
C2B
C2A
220uF/20mΩ 0.1uF
EN
FB
VCC
C5
R2
R5
SS
4.7uF 100K
30K
C6
33nF
PG
PGND
AGND
Figure 13 — Typical Application Circuit with No External Ramp
MPQ8612GL- 12, VIN=5V, VOUT=1.2V, IOUT= 12A, fSW=600kHz
VIN
C1A
22uF
C1B
22uF
C1C
22uF
C1D
R7
C1E
0.1uF 22uF
R6
100K
R8
10
360K
C7
1nF
BST
IN
R3
0
C3
1uF
VOUT
C4
R4
MPQ8612GL-12
220K
EN
FB
VCC
C5
L1
1uH
SW
FREQ
R5
470pF
R9
0
R1
33K
C2A
C2B
C3C
22uF
22uF
22uF 22uF
C2D
C2E
0.1uF
R2
30K
SS
4.7uF 100K
C6
33nF
PG
PGND
AGND
Figure 14 — Typical Application Circuit with Low ESR Ceramic Capacitor
MPQ8612GL- 12, VIN=5V, VOUT=1.2V, IOUT= 12A, fSW=600kHz
VIN
C1A
22uF
C1B
22uF
C1C
22uF
C1D
R7
C1E
0.1uF 22uF
R6
100K
R8
10
360K
C7
1nF
BST
IN
R3
0
C3
1uF
VOUT
C4
R4
200K
EN
MPQ8612
FB
VCC
C5
L1
1uH
SW
FREQ
560pF
Cdc
10nF
R1
29.1K
C2A
C2B
C3C
22uF
22uF
22uF 22uF
C2D
C2E
0.1uF
R2
R5
SS
4.7uF 100K
C6
33nF
PG
PGND
30K
AGND
Figure 15 — Typical Application Circuit with Low ESR Ceramic Capacitor
and DC-Blocking Capacitor.
MPQ8612GL- 12, VIN=5V, VOUT=1.2V, IOUT= 12A, fSW=600kHz
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MPQ8612 ― 12A/16A/20A, 6V, SYNCHRONOUS STEP-DOWN CONVERTER
LAYOUT RECOMMENDATION
1. The high current paths (GND, IN, and SW)
should be placed very close to the device
with short, direct and wide traces.
2. Put the input capacitors as close to the IN
and GND pins as possible.
3. Put the decoupling capacitor as close to the
VCC and GND pins as possible.
4. Keep the switching node SW short and away
from the feedback network.
5. The external feedback resistors should be
placed next to the FB pin. Make sure that
there is no via on the FB trace.
6. Keep the BST voltage path (BST, C3, and
SW) as short as possible.
7. Keep the IN and GND pads connected with
large copper to achieve better thermal
performance.
8. Four-layer layout is strongly recommended to
achieve better thermal performance.
V IN
R6
R5
C3
RFREQ
GND
EN
L1
VOUT
SW
FREQ
C4
R4
R1
MPQ8612
C2
FB
VCC
C5
Inner1 Layer
BST
IN
C1
GND
SS
R3
R2
C6
PG
PGND
AGND
Inner2 Layer
Schematic For PCB Layout Guide Line
SW
R3
C1B
SW
GND
IN
EN
PG
SS
VCC
R3
R3
1
FB
BST
AG ND
FREQ
R3
R5
R3
C1A
GND
R3
R6
R3
RFREQ
L1
GND
SW
IN
R3
C3
SW
IN
R3
C5
R3
R2
R3
C2
R3
C6
R3
R4
R3
R1
VIN
R3
C4
VIN
GND
Top Layer
GND
VOUT
VOUT
Bottom Layer
Figure 16—PCB Layout
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25
MPQ8612 ― 12A/16A/20A, 6V, SYNCHRONOUS STEP-DOWN CONVERTER
PACKAGE INFORMATION
QFN (3x4mm)
PIN 1 ID
MARKING
PIN 1 ID
INDEX AREA
BOTTOM VIEW
TOP VIEW
SIDE VIEW
NOTE:
0.1x45
°
1) ALL DIMENSIONS ARE IN MILLIMETERS.
2) EXPOSED PADDLE SIZE DOES NOT
INCLUDE MOLD FLASH.
3) LEAD COPLANARITY SHALL BE0.10
MILLIMETERS MAX.
4) JEDEC REFERENCE IS MO-220.
5) DRAWING IS NOT TO SCALE.
RECOMMENDED LAND PATTERN
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MPQ8612 ― 12A/16A/20A, 6V, SYNCHRONOUS STEP-DOWN CONVERTER
QFN (4x4mm)
NOTICE: The information in this document is subject to change without notice. Please contact MPS for current specifications.
Users should warrant and guarantee that third party Intellectual Property rights are not infringed upon when integrating MPS
products into any application. MPS will not assume any legal responsibility for any said applications.
MPQ8612 Rev. 1.11
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27
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