MP8760
High Efficiency, 6A, 18V,
Synchronous, Step-Down Converter
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The Future of Analog IC Technology
DESCRIPTION
FEATURES
The MP8760 is a fully-integrated, highfrequency, synchronous, rectified, step-down,
switch-mode converter. It offers a very compact
solution to achieve a 6A output current over a
wide input-supply range with excellent load and
line regulation. The MP8760 operates at high
efficiency over a wide output-current load range.
•
The MP8760 uses Constant-On-Time (COT)
control mode to provide fast transient response
and ease loop stabilization.
An external resistor programs the operating
frequency from 200kHz to 1MHz. The
frequency stays nearly constant as the input
supply
varies
with
the
feed-forward
compensation.
The default under voltage lockout threshold is
internally set at less than 4.1V, but a resistor
network on the enable pin can increase this
threshold. The soft start pin controls the output
voltage startup ramp. An open drain power
good signal indicates that the output is within
nominal voltage range.
It has full integrated protection features that
include over-current protection, over-voltage
protection and thermal shutdown.
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APPLICATIONS
•
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Set-Top Boxes
XDSL Modem/DSLAM
Small-Cell Base Stations
Personal Video Recorders
Flat-Panel Televisions and Monitors
Distributed Power Systems
All MPS parts are lead-free, halogen free, and adhere to the RoHS directive. For
MPS green status, please visit MPS website under Quality Assurance.
“MPS” and “The Future of Analog IC Technology” are Registered Trademarks
of Monolithic Power Systems, Inc.
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The MP8760 is available in a 3mm×4mm QFN
package, and requires a minimal number of
readily-available components.
•
2.5V to 18V Operating Input Range with
External 5V Bias
4.5V to 18V Operating Input Range with
Internal Bias
6A Output Current
Low RDS(ON) Internal Power MOSFETs
Proprietary Switching-Loss-Reduction
Technique
Adaptive COT for Ultrafast Transient
Response
1% Reference Voltage Over Junction
Temperature Range (0°C to +125°C)
Programmable Soft-Start Time
Pre-Bias Start-Up
Programmable Switching Frequency from
200kHz to 1MHz
Non-Latch OCP, OVP, and Thermal
Shutdown
Output Adjustable from 0.611V to 13V
TYPICAL APPLICATION
100
90
80
70
60
50
40
30
0.01
MP8760 Rev. 1.3
6/21/2016
0.1
1
10
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© 2016 MPS. All Rights Reserved.
1
MP8760 — 6A, 18V, SYNCHRONOUS STEP-DOWN CONVERTER
ORDERING INFORMATION
Package
Top Marking
MP8760GL*
QFN-13 (3mm×4mm)
MP8760
MP8760GLE**
QFN-16 (3mm×4mm)
MP8760E
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Part Number
* For Tape & Reel, add suffix –Z (e.g. MP8760GL–Z)
** For Tape & Reel, add suffix –Z (e.g. MP8760GLE–Z)
Note: The 16-pin QFN package is preferred and recommended for new designs
PACKAGE REFERENCE
TOP VIEW
EN
1
FREQ
2
FB
3
SS
4
AGND
5
PG
6
VCC
7
BS T
8
IN
PGND
13
12
TOP VIEW
PGND
11
9
10
SW
SW
13-Pin QFN (3x4mm)
Not Recommended for New Design
ABSOLUTE MAXIMUM RATINGS (1)
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Supply Voltage VIN .......................................21V
VSW ...................................... −0.3V to VIN + 0.3V
VSW (30ns) ................................. −3V to VIN + 3V
VBST .....................................................VSW + 6V
(2)
Enable Current IEN .................................................... 2.5mA
All Other Pins ................................ –0.3V to +6V
(3)
Continuous Power Dissipation (TA=+25°)
QFN3×4 .....................................................2.7W
Junction Temperature .............................. 150°C
Lead Temperature ................................... 260°C
Storage Temperature .............. −65°C to +150°C
Recommended Operating Conditions
(4)
Supply Voltage VIN .......................... 4.5V to 18V
Output Voltage VOUT.................... 0.611V to 13V
IEN ................................................ 0mA to 1mA
Operating Junction Temp. (TJ).−40°C to +125°C
MP8760 Rev. 1.3
6/21/2016
16-Pin QFN (3x4mm)
Recommended for New Design
Follow Layout
Performance
Recommendation
Thermal Resistance
(5)
θJA
for
Best
θJC
QFN (3×4mm) ........................ 46 ....... 9 .... °C/W
Notes:
1) Exceeding these ratings may damage the device.
2) Refer to the section “Configuring the EN Control”.
3) 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.
4) The device is not guaranteed to function outside of its
operating conditions.
5) Measured on JESD51-7, 4-layer PCB.
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© 2016 MPS. All Rights Reserved.
2
MP8760 — 6A, 18V, SYNCHRONOUS STEP-DOWN CONVERTER
ELECTRICAL CHARACTERISTICS
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VIN = 12V, TJ = +25°C, unless otherwise noted.
Parameters
Symbol
Condition
Min
Typ
Max
Units
0
1
µA
860
1000
µA
Supply Current
Supply Current (Shutdown)
IIN
VEN = 0V
Supply Current (Quiescent)
IIN
VEN = 2V, VFB = 1V
760
MOSFET
High-Side Switch-On
Resistance
HSRDS-ON
TJ =25°C
28
mΩ
Low-Side Switch-On Resistance
LSRDS-ON
TJ =25°C
16
mΩ
VEN = 0V, VSW = 0V or 12V
0
1
µA
Switch Leakage
SW LKG
Current Limit
Low-Side Valley Current Limit
Low-Side Negative Current
(6)
Limit
(6)
ILIMIT_VALLEY
6.5
7.5
8.5
A
ILIMIT_NEGATIVE
-4
-2.5
-1
A
Timer
One-Shot ON Time
250
ns
τON_MIN
30
ns
τOFF_MIN
360
ns
τON
(6)
Minimum ON Time
(6)
Minimum OFF Time
RFREQ=453kΩ, VOUT=1.2V
Over-Voltage and Under-Voltage Protection
OVP Non-Latch Threshold
VOVP_NON-
117%
120%
123%
LATCH
OVP Delay
UVP Threshold
(6)
VFB
τOVP
2
µs
VUVP
50%
VFB
Reference And Soft-Start
TJ = -40°C to +125°C
T
Reference Voltage
TJ = 0°C to +125°C
TJ = +25°C
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VREF
Feedback Current
IFB
VFB = 650mV
Soft-Start Charging Current
ISS
VSS=0V
(7)
(7)
602
611
620
605
611
617
605
611
617
50
100
nA
16
20
25
µA
1.1
1.3
1.5
V
mV
Enable And UVLO
Enable Input High Voltage
VIHEN
Enable Hysteresis
VEN-HYS
Enable Input Current
MP8760 Rev. 1.3
6/21/2016
IEN
250
VEN = 2V
0
VEN = 0V
0
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© 2016 MPS. All Rights Reserved.
mV
µA
3
MP8760 — 6A, 18V, SYNCHRONOUS STEP-DOWN CONVERTER
ELECTRICAL CHARACTERISTICS (continued)
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VIN = 12V, TJ = +25°C, unless otherwise noted.
Parameters
Symbol
Condition
Min
Typ
Max
Units
3.75
3.9
4.05
V
VCC Regulator
VCC Under-Voltage Lockout
Threshold Rising
VCC Under-Voltage Lockout
Threshold Hysteresis
VCCVth
VCCHYS
VCC Regulator
500
VCC
VCC Load Regulation
4.65
Icc=5mA
4.8
mV
4.95
0.5
V
%
Power Good
Power-Good, Rising Threshold
PGVth-Hi
Power-Good, Falling Threshold
PGVth-Lo
80%
VFB
Power-Good, Low-to-High Delay
PGTd
2.5
ms
Power Good, Sink Current
Capability
Power Good, Leakage Current
87%
VPG
Sink 4mA
IPG_LEAK
VPG = 3.3V
91%
10
94%
VFB
0.4
V
100
nA
Thermal Protection
Thermal Shutdown
(6)
Thermal Shutdown Hysteresis
TSD
(6)
°C
150
25
°C
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Note:
6) Guaranteed by design.
7) Not Production test, guaranteed by characterization
MP8760 Rev. 1.3
6/21/2016
www.MonolithicPower.com
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© 2016 MPS. All Rights Reserved.
4
MP8760 — 6A, 18V, SYNCHRONOUS STEP-DOWN CONVERTER
PIN FUNCTIONS
1
1
EN
2
2
FREQ
3
3
FB
4
4
SS
5
5
AGND
6
6
PG
7
7
VCC
8
8
BST
T
9,10
O
11, 12
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Name
Description
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PIN #
PIN#
13-Pin QFN 16-Pin QFN
13
MP8760 Rev. 1.3
6/21/2016
15, 16
SW
10, 11,
12 ,13
PGND
9,14
IN
Enable. Digital input to turn the regulator ON or OFF. Drive EN HIGH to
turn on the regulator. Drive it LOW to turn it off. Connect EN to IN through
a pull-up resistor or a resistive voltage divider for automatic startup. Do
not float this pin.
Frequency Set. Requires a resistor connected between FREQ and IN to
set the switching frequency. The input voltage and the resistor connected
to the FREQ pin determine the ON time. The connection to the IN pin
provides line feed-forward and stabilizes the frequency during input
voltage variation.
Feedback. Connect to the tab of an external resistor divider from the
output to GND to set the output voltage. FB is also configured to realize
over-voltage protection (OVP) by monitoring output voltage. Place the
resistor divider as close to FB pin as possible. Avoid using vias on the FB
traces.
Soft-Start. Connect an external capacitor to program the soft start time for
the switch mode regulator.
Analog ground. The control circuit reference.
Power Good, the output is an open drain signal. Require a pull-up resistor
to a DC voltage to indicate high if the output voltage exceeds 91% of the
nominal voltage. There is a delay from FB ≥ 91% to PG goes high.
Internal 4.8V LDO output. Power the driver and control circuits. 5V
external bias can disable the internal LDO. Decoupling with ≥1µF ceramic
capacitor as close to the pin as possible. Use X7R or X5R dielectric
ceramic capacitors for their stable temperature characteristics.
Bootstrap. Require a capacitor connected between SW and BST pins to
form a floating supply across the high-side switch driver.
Switch Output. Connect to the inductor and bootstrap capacitor. The highside switch drives the pin up to the VIN voltage during PWM duty cycle’s
ON time. The inductor current drives the SW pin negative during the
OFF-time. The low-side switch’s ON-resistance and the internal Schottky
diode clamp the negative voltage. Connect using wide PCB traces
System Ground. Reference ground of the regulated output voltage. PCB
layout requires extra care. Connect using wide PCB traces.
Supply Voltage. Supplies power to the internal MOSFET and regulator.
The MP8760 operates from a +2.5V to +18V input rail with 5V external
bias and a +4.5V to +18V input rail with internal bias. Requires an input
decoupling capacitor. Connect using wide PCB traces and multiple vias.
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© 2016 MPS. All Rights Reserved.
5
MP8760 — 6A, 18V, SYNCHRONOUS STEP-DOWN CONVERTER
TYPICAL CHARACTERISTICS
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VIN = 12V, VOUT = 1V, L = 1µH, TA = 25°C, unless otherwise noted.
MP8760 Rev. 1.3
6/21/2016
www.MonolithicPower.com
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© 2016 MPS. All Rights Reserved.
6
MP8760 — 6A, 18V, SYNCHRONOUS STEP-DOWN CONVERTER
TYPICAL CHARACTERISTICS (continued)
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VIN = 12V, VOUT = 1V, L = 1µH, TA = 25°C, unless otherwise noted.
5
700
1100
4.8
600
900
4.6
500
700
4.4
400
500
4.2
300
300
4
-50
0
50
100
150
200
-50
600
35
500
30
0
50
100
150
300
500
700
900
620
615
25
400
100
100
20
300
610
15
200
10
100
605
5
0
0
2.5
5
6
0
2
4
6
600
-50
0
50
100
150
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0
MP8760 Rev. 1.3
6/21/2016
www.MonolithicPower.com
MPS Proprietary Information. Patent Protected. Unauthorized Photocopy and Duplication Prohibited.
© 2016 MPS. All Rights Reserved.
7
MP8760 — 6A, 18V, SYNCHRONOUS STEP-DOWN CONVERTER
TYPICAL PERFORMANCE CHARACTERISTICS
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VIN = 12V, VOUT = 1V, L = 1µH, TA = 25°C, unless otherwise noted.
0.8
1.0
0.8
0.4
0.6
0.4
0
0.2
-0.4
-0.2
0.0
-0.4
-0.8
-0.6
-0.8
-1.2
-1.0
2
4
6
4
6
8
10 12
14
16
18
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0
MP8760 Rev. 1.3
6/21/2016
www.MonolithicPower.com
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© 2016 MPS. All Rights Reserved.
8
MP8760 — 6A, 18V, SYNCHRONOUS STEP-DOWN CONVERTER
TYPICAL PERFORMANCE CHARACTERISTICS (continued)
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VIN=12V, VOUT =1V, L=1µH, TA=+25°C, unless otherwise noted.
MP8760 Rev. 1.3
6/21/2016
www.MonolithicPower.com
MPS Proprietary Information. Patent Protected. Unauthorized Photocopy and Duplication Prohibited.
© 2016 MPS. All Rights Reserved.
9
MP8760 — 6A, 18V, SYNCHRONOUS STEP-DOWN CONVERTER
TYPICAL PERFORMANCE CHARACTERISTICS (continued)
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VIN=12V, VOUT =1V, L=1µH, TA=+25°C, unless otherwise noted.
Thermal Recovery
IOU T = 0A
V OUT
500mV/di
v.
SW
10V/di
v.
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IL
2A/di
v.
MP8760 Rev. 1.3
6/21/2016
www.MonolithicPower.com
MPS Proprietary Information. Patent Protected. Unauthorized Photocopy and Duplication Prohibited.
© 2016 MPS. All Rights Reserved.
10
MP8760 — 6A, 18V, SYNCHRONOUS STEP-DOWN CONVERTER
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BLOCK DIAGRAM
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Figure 1: Functional Block Diagram
MP8760 Rev. 1.3
6/21/2016
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© 2016 MPS. All Rights Reserved.
11
MP8760 — 6A, 18V, SYNCHRONOUS STEP-DOWN CONVERTER
OPERATION
In CCM, the switching frequency is fairly constant
and it is also called PWM mode.
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PWM Operation
The MP8760 is a fully-integrated, synchronous,
rectified, step-down, switch-mode converter. It
uses constant-on-time (COT) control to provide a
fast transient response and ease loop
stabilization.
At the beginning of each cycle, the high-side
MOSFET (HS-FET) turns ON when the feedback
voltage (VFB) drops below the reference voltage
(VREF), which indicates an insufficient output
voltage. The input voltage and the frequency-set
resistor determine the ON period as follows:
τON (ns) =
6.1× RFREQ (kΩ)
VIN (V) − 0.4
(1)
After the ON period elapses, the HS-FET turns
off. It turns ON again when VFB drops below VREF.
By repeating this operation, the converter
regulates the output voltage. The integrated lowside MOSFET (LS-FET) turns ON when the HSFET is OFF to minimize conduction loss and
avoid a dead short (or shoot-through) between
input and GND if both HS-FET and LS-FET turn
on at the same time. An internally-generated
dead-time (DT) between HS-FET OFF and LSFET ON or LS-FET OFF and HS-FET ON avoids
shoot-through.
Light-Load Operation
As the load decreases, the inductor current
decreases. The operation transitions from CCM
to discontinuous-conduction-mode (DCM) when
the inductor current reaches 0A.
Figure 3 shows light-load operation. When VFB
drops below VREF, HS-FET turns ON for a fixed
interval determined by the one- shot ON-timer as
per equation 1. When the HS-FET turns OFF, the
LS-FET turns ON until the inductor current
reaches zero. In DCM, the VFB does not reach
VREF when the inductor current reaches zero:
Instead, the LS-FET driver enters tri-state (high
Z). A current modulator then controls the LS-FET
and limits the inductor current to less than −1mA.
Hence, the output capacitors discharge slowly to
GND through LS-FET, and the HS-FET doesn’t
turn ON as frequently as under heavy-load
conditions, thus greatly improving light-load and
no-load efficiency. This is called skip mode.
Heavy-Load Operation
Figure 3: Light-Load Operation
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As the output current increases from the lightload, the current modulator shortens the
operating period to turn the HS-FET ON more
frequently. Hence, the switching frequency
increases. The output current reaches its critical
threshold when the current modulator time
decreases to zero. Determine the critical output
current level as follows:
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). Figure 2
shows the CCM operation. When VFB
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