MAX20014 [MAXIM]
2.2MHz Sync Boost and Dual Step-Down Converters;
| 型号： | MAX20014 |
| 厂家： | 
MAXIM INTEGRATED PRODUCTS |
| 描述： | 2.2MHz Sync Boost and Dual Step-Down Converters |
| 文件： | 总14页 (文件大小：608K) |
| 中文： | 中文翻译 | 下载： | 下载PDF数据表文档文件 |
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MAX20014
2.2MHz Sync Boost and
Dual Step-Down Converters
General Description
Benefits and Features
The MAX20014 is a high-efficiency three-output low-
voltage DC-DC converter. OUT1 boosts the input supply up
to 8.5V at up to 750mA, while two synchronous step-down
converters operate from a 3.0V to 5.5V input voltage range
and provides a 0.8V to 3.8V output voltage range at up to
3A. The boost converter achieves ±2% and the buck
converters achieve ±1.5% output error over load, line,
and temperature range.
● Multiple Functions for Small Size
• Synchronous 750mA Boost Converter
- Fixed from 3.8V to 8.5V in 100mV Steps
• Dual Synchronous Buck Converters Up to 3A
- Factory-Configurable Output Voltages from 0.8V
to 3.8V in 25mV Steps
- Resistor Adjustable
• 3.0V to 5.5V Operating Supply Voltage
• 2.2MHz Operation
• Undervoltage Threshold of 93% ±3%
• Overvoltage Threshold of 107% ±3%
• Individual RESET_ Outputs
The device features a 2.2MHz fixed-frequency pulse-width
modulation (PWM) mode for better noise immunity and
load transient response, and a pulse-frequency modula-
tion mode (skip) for increased efficiency during light-load
operation. The 2.2MHz frequency operation allows for the
use of all-ceramic capacitors and minimizes external com-
ponents footprint. The programmable spread-spectrum
frequency modulation minimizes radiated electromag-
● High-Precision
• ±1.5% Output-Voltage Accuracy
• Good Load Transient Performance for Buck Converters
● Robust for the Automotive Environment
• Current Mode, Forced-PWM, and Skip Operation
• Overtemperature and Short-Circuit Protection
• 4mm x 4mm 24-Pin TQFN
netic emissions. Integrated low R
efficiency at heavy loads and make the layout a much
simpler task with respect to discrete solutions.
switches improve
DS(ON)
• -40°C to +125°C Automotive Temperature Range
The device is offered with factory-preset output voltages or
resistor-adjustable output voltages. Other features include
soft-start, overcurrent, and overtemperature protections.
Ordering Information/Selector Guide appears at end of data
sheet.
Typical Operating Circuit
REG1
EN1
EN3
0.33µF
OUT1
22µF
EN2
3.3V
SYNC
3.3V
10Ω
LX1
PV
2.2µH
4.7µF
1µF
PGND1
GND
MAX20014
3.3V
PV[2:3]
2x4.7µF
RESET1 –
/3
RESET3
0.47µH
LX3
0.47µH
LX2
47µF
OUT3
47µF
OUT2
PGND3
PGND2
19-8532; Rev 3; 3/19
MAX20014
2.2MHz Sync Boost and
Dual Step-Down Converters
Absolute Maximum Ratings
PV2, PV3 to PGND_ ...............................................-0.3V to +6V
PV to GND...............................................................-0.3V to +6V
REG1 to GND..........................................-0.3V to V
GND to PGND......................................................-0.3V to +0.3V
LX1 Continuous RMS Current ................................................2A
LX2, LX3 Continuous RMS Current .......................................3A
Output Short-Circuit Duration....................................Continuous
+ 0.3V
OUT1
EN1―EN3, SYNC to GND...........................-0.3V to V + 0.3V
PV
RESET1―RESET3, GND........................................-0.3V to +6V
Continuous Power Dissipation (T = +70°C)
A
OUT1 to PGND1 ...................................................-0.3V to +10V
TQFN-EP (derate 30.3 mW/°C > +70°C) ..................2222mW
Operating Temperature .................................... -40°C to +125°C
Junction Temperature......................................................+150°C
Storage Temperature Range............................ -65°C to +150°C
Lead Temperature Range................................................+300°C
OUT2 to PGND2 ....................................... -0.3V to V
OUT3 to PGND3 ....................................... -0.3V to V
+ 0.3V
+ 0.3V
+ 0.3V
+ 0.3V
+ 0.3V
PV2
PV3
LX1 to PGND1.........................................-0.3V to V
OUT1
LX2 to PGND2........................................... -0.3V to V
LX3 to PGND3........................................... -0.3V to V
PV2
PV3
Stresses beyond those listed under “Absolute Maximum Ratings” may cause permanent damage to the device. These are stress ratings only, and functional operation of the device at these
or any other conditions beyond those indicated in the operational sections of the specifications is not implied. Exposure to absolute maximum rating conditions for extended periods may affect
device reliability.
(Note 1)
Package Thermal Characteristics
Junction-to-Ambient Thermal Resistance (θ ) ..............36°C/W
Junction-to-Case Thermal Resistance (θ ).....................3°C/W
JC
JA
Note 1: Package thermal resistances were obtained using the method described in JEDEC specification JESD51-7, using a four-layer
board. For detailed information on package thermal considerations, refer to www.maximintegrated.com/thermal-tutorial.
Electrical Characteristics
(V
= V
= V
= 3.3V, EN1 = EN2 = EN3 = 3.3V. T = T = -40°C to +125°C, unless otherwise noted. Typical values are at
PV
PV2
PV3 A J
T
= +25°C under normal conditions, unless otherwise noted.) (Note 2)
A
PARAMETER
SYMBOL
CONDITIONS
Fully operational
MIN
TYP
MAX
5.5
UNITS
Supply Voltage Range
V
3.0
V
IN
UVLO
Rising
2.7
2.6
2.2
2.9
R
Undervoltage Lockout (UVLO)
Shutdown Supply Current
V
UVLO
Falling
2.4
1
F
I
EN1–EN3 = low
5
µA
IN-SHDN
EN1 = high, I
= 0mA, skip,
OUT1
I
I
I
70
40
135
80
210
IN1
IN2
V
2% above regulation point
OUT1
EN2 = high, I
= 0mA, skip,
OUT2
Supply Current
160
µA
V
2% above regulation point
OUT2
EN3 = high, I
= 0mA, skip,
OUT3
40
80
160
2.4
IN3
V
2% above regulation point
OUT3
PWM Switching Frequency
Spread Spectrum
f
Internally generated
2.0
2.2
±3
MHz
%
SW
SS
Factory option enabled
OUT1 SYNCHRONOUS DC-DC BOOST CONVERTER
Voltage Accuracy
V
I
= 0A to I
, 3.0V ≤ V ≤ 3.6V
-2
125
75
+2
%
mΩ
mΩ
A
OUT1
LOAD
MAX
IN
pMOS On-Resistance
nMOS On-Resistance
nMOS Current-Limit Threshold
pMOS Turn-Off Threshold
R
V
= V
= 3.3V, I
= 0.1A
= 0.1A
250
150
2
500
300
HS1
PV
PV
PV2
PV2
LX1
LX1
R
V
= V
= 3.3V, I
LS1
I
1.6
15
LIM1
I
50
90
mA
ZX1
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MAX20014
2.2MHz Sync Boost and
Dual Step-Down Converters
Electrical Characteristics (continued)
(V
= V
= V
= 3.3V, EN1 = EN2 = EN3 = 3.3V. T = T = -40°C to +125°C, unless otherwise noted. Typical values are at
PV
PV2
PV3 A J
T
= +25°C under normal conditions, unless otherwise noted.) (Note 2)
A
PARAMETER
SYMBOL
CONDITIONS
MIN
TYP
MAX
UNITS
V
= V
= 6V, LX1 = PGND1 or
PV
PV2
LX1 Leakage Current
I
-1
+0.1
+1
µA
LX1LKG
OUT1, T = 25°C
A
Maximum Duty Cycle
OUT1 Discharge Resistance
OUT1 Discharge Current
Switching Phase
DC
75
440
10
%
Ω
MAX1
R
V
V
= 0V, V
= 0V, V
= 1V
200
4
700
18
DIS1
EN1
OUT1
I
= regulation point
mA
deg
V
DIS1
EN1
OUT1
PH
With respect to LX3 rising edge
> 4.5V
20
LX1
REG1 to OUT1
V
V
-5.1
5
-4.5
-3.9
30
REG1
OUT1
Percentage of nMOS current-limit
threshold
Skip Threshold
Soft-Start Time
SKIP
15
%
1
t
1.9
ms
SS1
OUT2 SYNCHRONOUS STEP-DOWN CONVERTER
I
= 0A to I
, 3.0V ≤ V ≤ 5.5V,
LOAD
MAX PV
Voltage Accuracy
V
-1.5
+1.5
%
OUT2
PWM mode selected
pMOS On-Resistance
nMOS On-Resistance
R
V
V
= V
= V
= 3.3V, I
= 3.3V, I
= 0.2A
= 0.2A
35
20
82
50
150
100
mΩ
mΩ
HS2
PV
PV2
LX2
R
LS2
PV
PV2
LX2
I
I
I
I
Factory option 1 (1A)
Factory option 2 (2A)
Factory option 3 (3A)
Factory option 4 (3.6A)
1.4
2.8
4.5
5.1
1.9
3.8
5.8
6.5
150
LIM2-1
LIM2-2
LIM2-3
LIM2-4
pMOS Current-Limit Threshold
A
nMOS Zero-Crossing Threshold
Maximum Duty Cycle
Minimum On-Time
I
mA
%
ZX2
DC
100
68
MAX2
t
25
20
44
40
ns
MINTON2
LX2 Discharge Resistance
Switching Phase
R
V
= 0V (connected to LX2)
80
Ω
DIS2
EN2
PH
180
deg
LX2
Percentage of pMOS current-limit
threshold
Skip Threshold
SKIP
4
12
20
%
2
Soft-Start Time
t
2.5
ms
SS2
OUT3 SYNCHRONOUS STEP-DOWN CONVERTER
I
= 0A to I
, 3.0V ≤ V ≤ 5.5V,
LOAD
MAX PV
Voltage Accuracy
V
-1.5
+1.5
%
OUT3
PWM mode selected
pMOS On-Resistance
nMOS On-Resistance
R
V
V
= V
= V
= 3.3V, I
= 3.3V, I
= 0.2A
= 0.2A
35
20
82
50
150
100
mΩ
mΩ
HS3
PV
PV3
LX3
R
LS3
PV
PV3
LX3
I
I
I
I
Option 1 (1A)
Option 2 (2A)
Option 3 (3A)
1.4
2.8
4.5
5.1
1.9
3.8
5.8
6.5
150
LIM3-1
LIM3-2
LIM3-3
LIM3-4
pMOS Current-Limit Threshold
nMOS Zero-Crossing Threshold
A
Factory option 4 (3.6A)
I
mA
ZX3
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MAX20014
2.2MHz Sync Boost and
Dual Step-Down Converters
Electrical Characteristics (continued)
(V
= V
= V
= 3.3V, EN1 = EN2 = EN3 = 3.3V. T = T = -40°C to +125°C, unless otherwise noted. Typical values are at
PV
PV2
PV3 A J
T
= +25°C under normal conditions, unless otherwise noted.) (Note 2)
A
PARAMETER
SYMBOL
DC
CONDITIONS
MIN
TYP
MAX
100
68
UNITS
%
Maximum Duty Cycle
Minimum On-Time
MAX3
MINTON3
t
25
20
44
40
0
ns
LX3 Discharge Resistance
Switching Phase
R
V
= 0V (connected to LX3)
80
Ω
DIS3
EN3
PH
With respect to LX3 rising edge
deg
LX3
Percentage of pMOS current-limit
treshold
Skip Threshold
SKIP
4
12
20
%
3
Soft-Start Time
t
2.5
ms
SS3
THERMAL OVERLOAD
Thermal-Shutdown Temperature
Hysteresis
T
T rising
165
15
°C
°C
SHDN
J
T
HYST
OUT1–OUT3 OPEN-DRAIN RESET OUTPUTS (RESET1–RESET3)
Overvoltage Threshold
Undervoltage Threshold
Active Hold Period
Delay Filter
OV
Rising, % of nominal output
104
90
107
93
110
96
%
%
UV
Falling, % of nominal output
t
7.4
10
ms
µs
HOLD
t
10% below/above threshold
PVDEL
RESET1–RESET3 High-Leakage
Current
I
-0.5
1.5
+0.1
+0.5
0.2
µA
V
PVOVLKG
Output Low Level
V
3.0V ≤ V ≤ 5.5V, sinking 2mA
PV
PVOL
EN1–EN3 AND SYNC INPUTS
Input High Level
V
V
V
IH
Input Low Level
V
0.5
IL
Input Hysteresis
V
0.1
0.5
0.1
100
V
ENHYST
EN1–EN3 Input Pulldown Current
EN1–EN3 Leakage Current
SYNC Input Pulldown
SYNC Input Frequency Range
SYNC OUTPUT
I
V
= 5.0V, T = +25°C
0.2
-1
µA
μA
kΩ
MHz
EN_PD
ENLKG
SYNCPD
PV
A
I
0 ≤ V ≤ 5.5V, T = +25°C
+1
200
2.6
PV
A
R
50
1.8
f
SYNC
Output Low
V
V
V
= 3.3V, I
= 2mA
SINK
0.4
V
V
OL
PV
Output High
V
= 3.3V, I = 2mA
SOURCE
2.7
OH
PV
Note 2: All units are 100% production tested at +25°C. All temperature limits are guaranteed by design.
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MAX20014
2.2MHz Sync Boost and
Dual Step-Down Converter
Typical Operating Characteristics
OUT2/3 EFFICIENCY
OUT1 EFFICIENCY
toc02
toc01
100
90
80
70
60
50
40
30
20
10
0
100%
VIN = 3.3V
VIN = 3.3V
VOUT1 = 5.0V
90%
80%
70%
60%
VOUT = 1.25V
VOUT = 1.8V
SKIP MODE
50%
SKIP MODE
PWM MODE
40%
30%
20%
10%
0%
PWM MODE
0.1
0.001
0.01
1
0.0001
0.001
0.01
0.1
1
OUT1 LOAD CURRENT (A)
OUT1 LOAD CURRENT (A)
OUT2/3 EFFICIENCY
OUT2/3 LOAD REGULATION
toc04
toc03
0.4%
0.3%
0.2%
0.1%
0.0%
-0.1%
-0.2%
-0.3%
-0.4%
100
VIN = 5V
VIN = 3.3V
VOUT = 1.8V
TA = 25°C
90
80
70
60
50
40
30
20
10
0
VOUT = 3.3V
VOUT = 1.8V
SKIP
MODE
PWM MODE
0
1
2
3
0.001
0.01
0.1
1
OUT1 LOAD CURRENT (A)
OUT1 LOAD CURRENT (A)
OUT2/3 LOAD TRANSIENT (PWM MODE)
OUT1 LOAD TRANSIENT (PWM MODE)
toc06
toc5
VIN = 3.3V
VOUT2 = 1.8V
20% ↔ 80% load step
VPV = 3.3V
OUT1 = 5V
50mV/div
(1.8V
offset)
100mV/
(5V offs
trf = 1µs
VOUT2
VOUT1
IOUT2
1A/div
IOUT1
200mA/
10µs/div
100µs/div
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MAX20014
2.2MHz Sync Boost and
Dual Step-Down Converters
Pin Configurations
TOP VIEW
18
17
16
15
14
13
19
20
21
22
23
24
12
11
10
9
GND
GND
SYNC
PV2
GND
PV3
MAX20014
LX3
LX2
8
PGND3
OUT3
PGND2
OUT2
+
7
1
2
3
4
5
6
TQFN
4mm x 4mm
Pin Description
PIN
1
NAME
FUNCTION
RESET3 Open-Drain RESET Output for OUT3. To obtain a logic signal, pull up RESET3 with an external resistor.
RESET2 Open-Drain RESET Output for OUT2. To obtain a logic signal, pull up RESET2 with an external resistor.
RESET1 Open-Drain RESET Output for OUT1. To obtain a logic signal, pull up RESET1 with an external resistor.
2
3
4
EN1
EN2
Active-High Enable Input for OUT1. Drive EN1 high for normal operation.
Active-High Enable Input for OUT2. Drive EN2 high for normal operation.
Active-High Enable Input for OUT3. Drive EN3 high for normal operation.
OUT2 Voltage Sense Input/Feedback Pin
5
6
EN3
7
OUT2
PGND2
LX2
8
Power Ground for OUT2. Connect all PGND pins together.
9
Inductor Connection. Connect LX2 to the switched side of the inductor.
Power Input Supply for OUT2. Connect a 4.7µF ceramic capacitor from PV2 to PGND2.
10
PV2
SYNC I/O. When configured as an input, connect SYNC to GND or leave unconnected to enable skip-mode
operation under light loads. Connect SYNC to PV or an external clock to enable fixed-frequency forced-
PWM-mode operation. When configured as an output (factory-configured), connect SYNC to other devices
SYNC inputs.
11
SYNC
12
13
14
15
16
17
GND
PGND1
LX1
Unused. Connect to ground.
Power Ground. Connect all PGND pins together.
Inductor Connection. Connect LX1 to the switched side of the inductor.
OUT1 Voltage Output
OUT1
REG1
GND
Floating Supply for OUT1. Connect a 0.33µF ceramic capacitor from REG1 to OUT1.
Analog Ground
Analog Input Supply. Connect a 1µF or larger ceramic capacitor from PV to GND with a 10Ω resistor in
series to the supply voltage.
18
PV
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MAX20014
2.2MHz Sync Boost and
Dual Step-Down Converters
Pin Description (continued)
PIN
19, 20
21
NAME
GND
FUNCTION
Unused. Connect to ground.
PV3
Power Input Supply for OUT3. Connect a 4.7µF ceramic capacitor from PV3 to PGND3.
Inductor Connection. Connect LX3 to the switched side of the inductor.
Power Ground for OUT3. Connect all PGND pins together.
OUT3 Voltage Sense Input/Feedback
22
LX3
23
PGND3
OUT3
24
Exposed Pad. Connect the exposed pad to ground. Connecting the exposed pad to ground does not
remove the requirement for proper ground connections to PGND. The exposed pad is attached with epoxy
to the substrate of the die, making it an excellent path to remove heat from the IC.
—
EP
mode to eliminate frequency variation, and help minimize
EMI. Protection features include cycle-by-cycle current
limit, and thermal shutdown with automatic recovery.
Detailed Description
The MAX20014 is
a
high-efficiency three-output
low-voltage DC-DC converter. OUT1 is a 750mA (typ)
synchronous DC-DC boost converter that boosts the 3.0V
to 5.5V input supply to a factory-set fixed-output voltage
between 3.8V and 8.5V in 100mV steps. The boost convert-
er has true shutdown so the output voltage is 0V when off.
The two synchronous step-down converters (OUT2, OUT3)
operate from a 3.0V to 5.5V input voltage and provide a
0.8V to 3.80V output voltage at up to 3A. OUT2 and OUT3
can be factory set to a fixed voltage or resistor adjustable.
The boost converter achieves ±2% and the buck con-
verters achieve ±1.5% output error over load, line, and
temperature range.
Enable Inputs (EN1―EN3)
The enable control inputs (EN1―EN3) activate the device
channel from their low-power shutdown state. EN1―EN3
have an input threshold of 1.0V (typ) with hysteresis of
100mV (typ). EN1―EN3 are fully independent with no
timing restrictions between each other. When an enable
input goes high, the associated output voltage ramps up
with the programmed soft-start time.
Reset Outputs (RESET1―RESET3)
The device features individual open-drain reset outputs
for each output that asserts low when the correspond-
ing output voltage is outside of the UV/OV window.
RESET1―RESET3 remain asserted for a fixed timeout
period after the output rises up to its regulated voltage.
The fixed timeout period is selectable between 0.8ms,
3.7ms, 7.4ms (default), or 14.9ms. See the Ordering
Information/Selector Guide table. To obtain a logic signal,
place a pullup resistor between the RESET1―RESET3
pins to the system I/O voltage.
The device features a 2.2MHz fixed-frequency PWM
mode for better noise immunity and load-transient
response, and a pulse-frequency modulation mode (skip)
for increased efficiency during light-load operation. The
2.2MHz frequency operation allows for the use of all-
ceramic capacitors and minimizes external components.
The programmable spread-spectrum frequency modula-
tion minimizes radiated electromagnetic emissions. The
spread modulation can be factory set to pseudorandom.
Integrated low R
switches improve efficiency at
heavy loads and make the layout a much simpler task
DS(ON)
Feedback Pins (OUT1―OUT3)
The output voltage is fed back to the coresponding OUT_
feedback pin to close the regulation loop. If this connection
is open, the output turns off to prevent open-loop operation
that would normally result in the output being driven to the
input supply voltage. For a fixed-output voltage, connect
OUT_ directly to the output. For an adjustable-output volt-
age, connect a resistor-divider to the output and connect
OUT_ to the midpoint. The boost converter output is not
resistor adjustable.
with respect to discrete solutions.
The device contains high-accuracy overvoltage/under-
voltage thresholds for each output that is mapped to
the RESET1―RESET3] pins. There are diagnostics on
RESET1―RESET3] and OUT1―OUT3 to guarantee high
reliablilty and fail-safe operation.
In light-load applications, a logic input (SYNC) allows
the devices to operate either in skip mode for reduced
current consumption, or fixed-frequency, forced-PWM
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MAX20014
2.2MHz Sync Boost and
Dual Step-Down Converters
Internal Block Diagram
OUT1
CS
AMP
SKIP
CLK
COMP
OUT1
RAMP
GENERATOR
ILIM
COMP
∑
CONTROL LOGIC
OUT1
LDO
LX1
REG1
PV1
PWM
REG1
COMP
V
REF
V
REF2
PGND1
SOFT-START
GENERATOR
EAMP
FPWM CLK
OUT1
UV/OV
PGND1
ZX, NEG
ILIM
PV2, PV3
CS
AMP
SKIP
CLK
COMP
PV1
RAMP
GENERATOR
ILIM
COMP
∑
CONTROL LOGIC
PGND1
PV1
LX2, LX3
PWM
COMP
V
REF
PGND1
SOFT-START
GENERATOR
V
REF2
EAMP
FPWM CLK
ZX, NEG
ILIM
OUT2,
OUT3
UV/OV
PGND2,
PGND3
VALLEY
ILIM
CLK
CLK180
FPWM
VOLTAGE
REFERENCE
OTP
V
REF
SYNC
OSC
POK[1:3]
PV
EN1
EN2
EN3
RESET1
RESET2
RESET3
MAIN
CONTROL
LOGIC
RESET1
RESET2
RESET3
RESET1–RESET3
UV/OV
GND
V
REF2
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MAX20014
2.2MHz Sync Boost and
Dual Step-Down Converters
When configured as a load switch, the RESET3 output
indicates when the pMOS switch is fully closed and not
the actual voltage on the output. The normal hold time
still applies.
Internal Oscillator
The device has a spread-spectrum oscillator that varies
the internal operating frequency up by ±3% relative to the
internally generated operating frequency of 2.2MHz (typ).
This function does not apply to externally applied oscillation
frequency. The spread frequency generated is pseudoran-
dom, with a repeat rate well below the audio band.
Current Limit/Short-Circuit Protection
The device features current limit that protects the device
against short-circuit and overload conditions at the output.
In the event of a short-circuit or overload condition, the
high-side MOSFET remains on until the inductor current
reaches the high-side MOSFET’s current-limit thresh-
old. The converter then turns on the low-side MOSFET
to allow the inductor current to ramp down. Once the
inductor current crosses below the low-side MOSFET
current-limit threshold, the converter turns on the high-
side MOSFET again. This cycle repeats until the short or
overload condition is removed.
Synchronization (SYNC)
SYNC is factory-programmable I/O. See the Ordering
Information/SelectorGuidetableforavailableoptions.When
configuredasaninput, alogic-highonSYNCenablesfixed-
frequency, forced-PWM mode. Apply an external clock on
the SYNC input to synchronize the internal oscillator to an
external clock. The SYNC input accepts signal frequen-
cies in the range of 1.8MHz < f
< 2.6MHz. When
SYNC
the pin is open or logic-low, the SYNC input enables the
device to enter a low-power skip mode under light-load
conditions. When configured as an output, SYNC outputs
the internally generated 2.2MHz clock that switches from
PV to GND. All converters operate in forced-PWM mode
when SYNC is configured as an output.
PWM and Skip Modes
The device features a SYNC input that puts the converter
either in skip mode for forced-PWM mode of operation.
See the Pin Description table for more details. In PWM
mode, the converter switches at a constant frequency with
variable on-time. In skip mode of operation, the converter’s
switching frequency is load dependent until the output
load reaches a certain threshold. At higher load current,
the switching frequency does not change and the operat-
ing mode is similar to the PWM mode. Skip mode helps
improve efficiency in light-load applications by allowing
the converter to turn on the high-side switch only when
the output voltage falls below a set threshold. As such, the
converter does not switch MOSFETs on and off as often as
is the case in PWM mode. Consequently, the gate charge
and switching losses are much lower in skip mode.
Soft-Start
The device includes a fixed soft-start of 1.9ms for OUT1
and 2.5ms for OUT2/OUT3. Soft-start time limits startup
inrush current by forcing the output voltage to ramp up
towards its regulation point.
OUT3 Load-Switch Option
OUT3 of the device can be factory trimmed to operate as a
load switch. In this configuration, LX3 becomes the output
and OUT3 must be connected to GND. When EN3 goes
high, the high-side pMOS current ramps from 0 to I
in
MAX
500µs (typ) to limit the inrush current. The pMOS switch
is also protected from short circuit. When a short circuit
is detected, the pMOS turns off and reinitiates a soft-start
sequence. For proper operation, the peak current through
the pMOS switch must be kept below 4.2A during soft-
start. This limits the maximum output capacitor value
depending on the output voltage and load conditions. It is
recommended that the output capacitor does not exceed
47µF.
Overtemperature Protection
Thermal-overload protection limits the total power
dissipation in the MAX20014. When the junction
temperature exceeds +165°C (typ), an internal thermal
sensor shuts down the internal bias regulator and the
step-down controller, allowing the device to cool. The
thermal sensor turns on the device again after the junction
temperature cools by 15°C.
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MAX20014
2.2MHz Sync Boost and
Dual Step-Down Converters
The second factor in inductor selection is slope compen-
sation. The inductor current down-slope (m2) must be
less than twice the internal slope compensation down-
ramp (m1) to dampen oscillations in the inductor current
waveform. Perfect deadbeat control occurs when the two
downslopes are equal. The inductor current downslope is
given by the formula below.
Applications Information
Input Capacitors
The input filter capacitor reduces peak currents drawn
from the power source and reduces noise and voltage
ripple on the input caused by the circuit’s switching. A
4.7µF X7R ceramic capacitor is recommended for the
PV2 and PV3 pins, as well as the supply side pin of
the boost inductor. A 1.0µF X7R ceramic capacitor is
recommended for the PV pin, with a 10Ω resistor in series
to the input supply.
Equation 5:
m2 = (V
- V )/L
IN
OUT
The internal slope compensation ramp for the boost
channel is set at 0.630 V/µs, and the R for the boost
CS
Boost Inductor Selection and Output Current
Proper choice of inductor for the boost converter is based
on ripple current and slope compensation. Ripple current
channel is fixed at 0.330Ω. This provides a compensation
ramp downslope of:
Equation 6:
(I ) is usually specified as a percentage of the aver-
PK-PK
m1 = 0.630/R
CS
age input current. 33% peak-to-peak ripple provides a
reasonable balance between inductor size, DCR, and core
losses.
Setting the inequality, adding in a margin factor of 1.3
for device and component variation, and rearranging for
inductance gives the following.
The peak boost input current limit is 1.6A (min), so the
average current as a function of I
is shown below.
PK-PK
Equation 7:
Equation 1:
L
≥ 1.3 · R
x (V - V )/(0.630 x 2)
OUT IN
MIN2
CS
I
= 1.6/(1 + I
/2)
IN
PK-PK
This gives the minimum inductance necessary for satisfy-
ing slope compensation (half inductor downslope). The
minimum inductance acceptable for use is the greater of
the two calculated minimum values.
For 33% ripple, this equates to 1.37A for I and 0.45A rip-
ple current (denoted I , which has a unit of A, as opposed
IN
Δ
to I
, which is a percentage). With the maximum
PK-PK
average current I known, the maximum output current
for a given duty cycle (D) is shown below.
IN
Equation 8:
L
= max(L
, L
)
MIN
MIN1 MIN2
Equation 2:
The maximum recommended inductance is twice the
minimum value.
I
= (1-D) x I
IN
OUT-MAX
where (see Equation 3):
Equation 9:
Equation 3:
L
< L < 2 x L
NOM MIN
MIN
D = 1 - η x V /V
IN OUT
Soft-saturation type inductors are recommended, as they
maintain a measure of effective inductance even when
driven past their saturation points during fault conditions.
If a ferrite-based inductor is used, then the saturation
current must be higher than the maximum current limit
in order to help protect the part during continuous output
short-circuit events.
If η (efficiency) is not known, it must be measured or esti-
mated. A good efficiency estimate is 0.9 (90%) for V /V
OUT IN
ratios of 1.5 or less, and 0.8 for V
/V ratios near 2.5.
OUT IN
The approximate minimum inductance necessary to
achieve a given ripple current I is shown below.
Δ
Equation 4:
L
= (V x D)/(f
x I )
SW Δ
MIN1
IN
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MAX20014
2.2MHz Sync Boost and
Dual Step-Down Converters
Equation 11:
Buck Inductor Selection
Three key inductor parameters must be specified for
operation with the MAX20014: inductance value (L), peak
m2
-m ≥
2
inductor current (I
), and inductor saturation current
PEAK
(I
). The minimum required inductance is a function
SAT
where:
m2
of operating frequency, input-to-output voltage differen-
tial, and the maximum output current capability of the
output. A lower inductor value minimizes size and cost,
improves large-signal and transient response, but reduces
efficiency due to higher peak currents and higher peak-to-
peak output-voltage ripple for the same output capacitor.
On the other hand, higher inductance increases efficiency
by reducing the ripple current. Resistive losses due to
extra wire turns can exceed the benefit gained from
lower ripple current levels especially when the inductance
is increased without also allowing for larger inductor
V
OUT
L
The inductor current downslope.
× R
CS
Slope compensation.
V
0.940
for V
> 3.2V fixed output.
≤ 3.2V fixed output or
OUT
µs
-m
V
0.535
for V
OUT
µs
dimensions. The MAX20014 is designed for ΔI
equal
P-P
adjustable output version.
to ~30% of the full load current. Use the following
equation to calculate the inductance.
0.378Ω for 1A channel
0.263Ω for 2A channel
0.176Ω for 3A channel
R
CS
Equation 10:
V
- V
× V
OUT
(
)
IN
OUT_
L
=
MIN1
V
× f
×I
× 30%
IN SW MAX
Solving for L and adding a 1.3 multiplier to account for
tolerances in the system, is shown below.
V
The nominal input voltage (3.3V or 5V, typ).
The nominal output voltage.
IN
Equation 12:
V
I
OUT_
1A, 2A, or 3A depending on part number and
channel. Use the maximum output capability of
the output channel for the channel being used.
R
CS
L
= V
×
OUT_
×1.3
MAX
MIN2
MIN1
2×m
The operating frequency. This value is 2.2MHz
unless externally synchronized to a different
frequency.
To satisfy both L
larger of the two.
and L
, L
must be set to the
MIN2 MIN
f
SW
Equation 13:
V
and V
are typical values so that efficiency is
IN
OUT
L
= Max (L
, L
)
MIN
MIN1 MIN2
optimum for typical conditions. The switching frequency
is 2.2MHz. The maximum output capability (I
The maximum inductor value recommended is 2 times the
chosen value from the above formula.
f
)
MAX
( SW)
is 1A, 2A, or 3A based on the specific part number of the
device. See the Boost Output Capacitor section to verify
thattheworst-caseoutputrippleisacceptable.Theinductor
saturation current is also important to avoid runaway
current during continuous output short circuit.
Equation 14:
L
MAX
= 2 x L
MIN
Select a nominal inductor value based on the following
formula. For optimal performance select the first standard
The next equation ensures that the inductor current
downslope is less than the internal slope compensation.
For this to be the case, the following equation needs to be
satisfied.
inductor value greater than L
.
MIN
Equation 15:
L
MIN
< L
< L
NOM MAX
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MAX20014
2.2MHz Sync Boost and
Dual Step-Down Converters
Boost Output Capacitor
Adjustable Output-Voltage Option
The MAX20014 is designed to be stable with low-
ESR ceramic capacitors. Other capacitor types are not
recommended as the ESR zero can affect stability of
the device. The output capacitor calculations below are
guidelines based on nominal conditions. The phase
margin must be measured on the final circuit to verify
proper stability is achieved.
The MAX20014 adjustable output-voltage ver-
sion allows the customer to set the buck out-
puts to any voltage between 0.8V and approximate-
ly PV - 0.5V (see the Ordering Information/Selector
Guide). The
actual
maximum
output-voltage
setting is limited by the specific application conditions
and components. Connect a resistive divider from the
output capacitor (V
voltage (Figure 1). Select R (OUT_ to GND resistor) ≤
100kΩ. Calculate R (V
equation below.
) to OUT_ to GND to set the output
OUT
Equation 16:
2
50 × A ×µs
to OUT_ resistor) with the
C
=
=
1
OUT
OUT_MIN
V
OUT
100× A ×µs
Equation 18:
C
OUT1_NOM
V
OUT
V
OUT
R = R
−1
2
1
V
FB
Buck Output Capacitors
The MAX20014 is designed to be stable with low
ESR ceramic capacitors. Other capacitor types are not
recommended as the ESR zero can affect stability of
the device. The output capacitor calculations below are
guidelines based on nominal conditions. The phase
margin must be measured on the final circuit to verify that
proper stability is achieved.
where V = 800mV (see the Electrical Characteristics).
FB
The external feedback resistive divider must be frequency
compensated for proper operation. Place a capacitor
across R1 in the resistive-divider network. Use Equation
20 to determine the value of the capacitor.
Equation 19:
Equation 17:
R
R
2
1
I
C = 50
pF
MAX
1
C
= 10.5µs×
= 27.5µs×
OUT23_MIN
V
I
OUT
MAX
Figure 1
C
OUT23_NOM
V
OUT
V
OUT
The minimum fully-derated output capaci-
tance needed for a stable output.
R
C
1
1
C
OUT23-MIN
OUT_
C
The nominal output capacitance.
OUT23-NOM
The maximum DC current capability. Either
1A, 2A, or 3A. depending on the part number
(see the Ordering Information/Selector
Guide).
R
2
I
MAX
V
Nominal output voltage.
OUT
Figure 1. Adjustable Output-Voltage Configuration
with C
defining the minimum fully derated out-
OUT23_MIN
put capacitance required for a stable output, and C
OUT23_
defining the nominal output capacitance for maxi-
NOM
mum phase margin. I
is the maximum DC current
MAX
capability of the associated output, as defined in the
Ordering Information/Selector Guide table. V
is the
OUT
output voltage for the associated channel.
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MAX20014
2.2MHz Sync Boost and
Dual Step-Down Converters
The layer directly below the IC and power components
should be a continuous ground plane. Use multiple vias
to provide good connections between that plane and
component ground pins/pads. Split grounding should not
be used.
PCB Layout Guidelines
For each converter, place the capacitor with the highest
current ripple closest to the IC. For a buck converter, this
is the input capacitor; for the boost converter, it is the out-
put capacitor. Route the LX trace out from the IC under-
neath that capacitor (use a larger-package capacitor,
such as 3.2mm x 1.6mm). Lastly, place the other capaci-
tors close by with their ground pins very close to both the
IC’s ground pins and the other capacitor’s ground pins.
This configuration results in a closely-routed DC/DC con-
verter that helps maintain performance and reduces EMI.
The exposed pad (EP) of the IC is attached to the die with
epoxy, providing a good way to dissipate thermal energy
from the die. Connect the EP to all available ground
planes below it using a grid of small vias in the EP land
(3x3 grid of 0.3mm diameter vias is recommended).
Ordering Information/Selector Guide
TEMPERATURE
RANGE
V
OUT1
(V)
V
OUT2
(V)
I
V
OUT3
(V)
I
t
OUT2
(A)
OUT3
(A)
HOLD
(ms)
PART NUMBER
PIN-PACKAGE
SS
MAX20014ATGA/V+
MAX20014ATGB/V+**
-40°C to +125°C 24 TQFN-EP*
-40°C to +125°C 24 TQFN-EP*
5.0
6.5
5.0
7.5
5.0
5.0
ADJ
ADJ
1.2
3
3
3
2
3
3
ADJ
ADJ
1.8
3
3
3
1
3
3
7.4
7.4
7.4
7.4
7.4
7.4
Off
Off
Off
On
On
On
MAX20014ATGC/V+** -40°C to +125°C 24 TQFN-EP*
MAX20014ATGD/V+** -40°C to +125°C 24 TQFN-EP*
ADJ
1.4
ADJ
1.5
MAX20014ATGE/V+**
MAX20014ATGF/V+
-40°C to +125°C 24 TQFN-EP*
-40°C to +125°C 24 TQFN-EP*
ADJ
ADJ
For variants with different options, contact factory.
/V denotes an automotive qualified part.
+Denotes a lead(Pb)-free/RoHS-compliant package.
*EP = Exposed pad.
**Future product—contact factory for availability.
Package Information
For the latest package outline information and land patterns (footprints), go to www.maximintegrated.com/packages. Note that a “+”,
“#”, or “-” in the package code indicates RoHS status only. Package drawings may show a different suffix character, but the drawing
pertains to the package regardless of RoHS status.
PACKAGE TYPE
PACKAGE CODE
OUTLINE NO.
LAND PATTERN NO.
24 TQFN-EP*
T2444+4C
21-0139
90-0022
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MAX20014
2.2MHz Sync Boost and
Dual Step-Down Converters
Revision History
REVISION REVISION
PAGES
CHANGED
DESCRIPTION
NUMBER
DATE
11/16
5/18
0
1
2
3
Initial release
—
Various updates
1–12
12/18
3/19
Added MAX20014ATGF/V+ to Ordering Information/Selector Guide table
Updated Ordering Information/Selector Guide
13
13
For pricing, delivery, and ordering information, please contact Maxim Direct at 1-888-629-4642, or visit Maxim Integrated’s website at www.maximintegrated.com.
Maxim Integrated cannot assume responsibility for use of any circuitry other than circuitry entirely embodied in a Maxim Integrated product. No circuit patent licenses
are implied. Maxim Integrated reserves the right to change the circuitry and specifications without notice at any time. The parametric values (min and max limits)
shown in the Electrical Characteristics table are guaranteed. Other parametric values quoted in this data sheet are provided for guidance.
©
Maxim Integrated and the Maxim Integrated logo are trademarks of Maxim Integrated Products, Inc.
2019 Maxim Integrated Products, Inc.
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