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MAX17220–MAX17225
400mV to 5.5V Input, nanoPower Synchronous
Boost Converters with True Shutdown
General Description
Benefits and Features
The MAX17220–MAX17225 is a family of ultra-low quiescent current boost (step-up) DC-DC converters with a
225mA/0.5A/1A peak inductor current limit and True Shutdown™. True Shutdown disconnects the output from the
input with no forward or reverse current. The output voltage is selectable using a single standard 1% resistor. The
225mA (MAX17220/MAX17221), 500mA (MAX17222/
MAX17223), and 1A (MAX17224/MAX17225) peak inductor current limits allow flexibility when choosing inductors.
The MAX17220/MAX17222/MAX17224 versions have
post-startup enable transient protection (ETP), allowing
the output to remain regulated for input voltages down
to 400mV, depending on load current. The MAX17220–
MAX17225 offer ultra-low quiescent current, small total
solution size, and high efficiency throughout the entire
load range. The MAX17220–MAX17225 are ideal for battery applications where long battery life is a must.
● 300nA Quiescent Supply Current into OUT
● True Shutdown Mode
• 0.5nA Shutdown Current
• Output Disconnects from Input
• No Reverse Current with VOUT 0V to 5V
● 225mA, 500mA, and 1A Peak Inductor Current Limit
• MAX17220/MAX17221: 225mA ILIM
• MAX17222/MAX17223: 500mA ILIM
• MAX17224/MAX17225: 1A ILIM
● MAX17220/MAX17222/MAX17224 Enable Transient
Protection (ETP)
● 2mm x 2mm, 6-Pin μDFN
● 0.88mm x 1.4mm, 6-Bump WLP (2 x 3, 0.4mm Pitch)
Typical Operating Circuit
L1 2.2µH
IN
400mV TO 5.5V
CIN
10µF
OUT
OUT
LX
EN
IN
COUT
10µF
MAX1722X
GND
SEL
STARTUP
0.88 (TYP)
GND
● Optical Heart-Rate Monitoring (OHRM) LED Drivers
● Supercapacitor Backup for Real-Time Clock (RTC)/
Alarm Buzzers
● Primary-Cell Portable Systems
● Tiny, Low-Power IoT Sensors
● Secondary-Cell Portable Systems
● Wearable Devices
● Battery-Powered Medical Equipment
● Low-Power Wireless Communication Products
95% Peak Efficiency
400mV to 5.5V Input Range
0.88V Minimum Startup Voltage
1.8V to 5V Output Voltage Range
• 100mV/Step
• Single 1% Resistor-Selectable Output
EN
Applications
●
●
●
●
RSEL
Arm and Cortex are registered trademarks of Arm Limited.
Bluetooth is a registered trademark of Bluetooth SIG, Inc.
True Shutdown is a trademark of Maxim Integrated Products, Inc.
Ordering Information appears at end of data sheet.
19-8753; Rev 8; 10/21
© 2021 Analog Devices, Inc. All rights reserved. Trademarks and registered trademarks are the property of their respective owners.
One Analog Way, Wilmington, MA 01887 U.S.A. | Tel: 781.329.4700 | © 2021 Analog Devices, Inc. All rights reserved.
MAX17220–MAX17225
400mV to 5.5V Input, nanoPower Synchronous
Boost Converters with True Shutdown
Absolute Maximum Ratings
OUT, EN, IN to GND ................................................ -0.3V to +6V
RSEL to GND ................. -0.3V to Lower of (VOUT + 0.3V) or +6V
LX RMS Current WLP ............................... -1.6ARMS to 1.6ARMS
LX RMS Current μDFN .................................. -1ARMS to +1ARMS
LX to GND (Note 1) .................................... -0.3V to VOUT + 0.3V
Continuous Power Dissipation (TA = +70°C)
WLP (derate 10.5mW/°C above +70°C) ....................... 840mW
Continuous Power Dissipation (TA = +70°C)
μDFN (derate 4.5mW/°C above +70°C) .....................357.8mW
Operating Temperature Range ...........................-40°C to +125°C
Junction Temperature ....................................................... +150°C
Storage Temperature Range ..............................-40°C to +150°C
Soldering Temperature (reflow) ........................................ +260°C
Note 1: The LX pin has internal clamps to GND and OUT. These diodes may be forward biased during switching transitions. During
these transitions, the maximum LX current should be within the maximum RMS current rating for safe operation.
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.
Package Information
μDFN
Package Code
L622+1C
Outline Number
21-0164
Land Pattern Number
90-0004
THERMAL RESISTANCE, FOUR-LAYER BOARD
Junction to Ambient (θJA)
223.6°C/W
Junction to Case (θJC)
122°C/W
WLP
Package Code
N60E1+1
Outline Number
21-100128
Land Pattern Number
Refer to Application Note 1891
THERMAL RESISTANCE, FOUR-LAYER BOARD
Junction to Ambient (θJA)
95.15°C/W
Junction to Case (θJC)
N/A
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 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.
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Analog Devices | 2
MAX17220–MAX17225
400mV to 5.5V Input, nanoPower Synchronous
Boost Converters with True Shutdown
Electrical Characteristics
(VIN = VEN = 1.5V, VOUT = 3V, TA = -40°C to +125°C, typical values are at TA = +25°C, unless otherwise noted. (Note 2))
PARAMETER
Minimum Input Voltage
Input Voltage Range
SYMBOL
CONDITIONS
VIN_MIN
Runs from output after startup, IOUT =
1mA
VIN
Guaranteed by LX Maximum On-Time
MIN
TYP
MAX
400
0.95
mV
5.5
V
0.95
V
Minimum Startup Input
Voltage
VIN_STARTUP
Output Voltage Range
VOUT
See RSEL Selection Table.
For VIN < VOUT target (Note 3)
1.8
5
V
Output Accuracy, LPM
ACCLPM
VOUT falling, when LX switching
frequency is > 1MHz (Note 4)
-1.5
+1.5
%
Output Accuracy, UltraLow-Power Mode
ACCULPM
VOUT falling, when LX switching
frequency is > 1kHz (Note 5)
1
2.5
4
%
TA= +25°C.
300
600
TA = +85°C
470
900
Quiescent Supply
Current Into OUT
Quiescent Supply
Current Into IN
IQ_OUT
IQ_IN
MAX17220/2/4
EN = open after
startup,
MAX17221/3/5 EN
= VIN,
not switching,
RSEL OPEN,
VOUT = 104% of
1.8V
nA
MAX17220/2/4
EN = open after
startup MAX17221/
3/5 EN = VIN,
not switching,
RSEL OPEN,
VOUT = 104% of
1.8V
TA = +125°C
1000
VOUT = 104% of
1.8V,
TA = +25°C
0.1
0.5
ISD_IN
MAX17220/1/2/3/4/5, RL = 3kΩ,
VOUT = VEN = 0V, TA = +25°C
0.1
ISD_TOTAL
MAX17220/1/2/3/4/5, RL= 3kΩ,
VEN = 0V, TA = +25°C
0.5
IQ_IN_TOTAL
Shutdown Current Into
IN
Total Shutdown Current
into IN, LX
IPEAK
(Note 6)
LX Maximum Duty Cycle
DC
(Note 7)
LX Maximum On-Time
tON
(Note 7)
LX Minimum Off-Time
tOFF
(Note 7)
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0.88
MAX17220/2/4 EN = Open after startup.
MAX17221/3/5 EN = VIN, not switching,
VOUT = 104% of 1.8V, total current
includes IN, LX, and EN, TA = +25°C
Total Quiescent Supply
Current into IN, LX, EN
Inductor Peak Current
Limit
RL ≥ 3kΩ, Typical Operating Circuit, TA =
+25°C
UNITS
2000
nA
100
nA
nA
100
nA
mA
MAX17220/1
180
225
270
MAX17222/3
0.4
0.5
0.575
MAX17224/5
0.8
1
1.2
70
75
VOUT = 1.8V
280
365
450
VOUT = 3.0V
270
300
330
VOUT = 1.8V
90
120
150
VOUT = 3.0V
80
100
120
A
%
ns
ns
Analog Devices | 3
MAX17220–MAX17225
400mV to 5.5V Input, nanoPower Synchronous
Boost Converters with True Shutdown
Electrical Characteristics (continued)
(VIN = VEN = 1.5V, VOUT = 3V, TA = -40°C to +125°C, typical values are at TA = +25°C, unless otherwise noted. (Note 2))
PARAMETER
LX Leakage Current
N-Channel OnResistance
P-Channel OnResistance
Synchronous Rectifier
Zero-Crossing as
Percent of Peak Current
Limit
Enable Voltage
Threshold
SYMBOL
ILX_LEAK
RDS(ON)
RDS(ON)
IZX
VIL
VIH
CONDITIONS
VOUT = VEN = 0V,
MAX17220
VOUT = 3.3V
VOUT = 3.3V
MIN
TYP
0.3
VLX = 5.5V, TA=
+85°C
30
VLX = 5.5V, TA=
+125°C
400
MAX17220/1
124
270
MAX17222/3
62
135
31
70
MAX17220/1
300
600
MAX17222/3
150
300
MAX17224/5
75
150
7.5
VOUT = 3.3V (Note 8)
2.5
5
When LX switching stops, EN falling, TA
= -40°C to +85°C
250
500
When LX switching stops, EN falling, TA
= -40°C to +125°C
150
EN rising, TA = -40°C to +85°C
mΩ
mΩ
%
mV
600
EN rising, TA = -40°C to +125°C
850
900
0.1
MAX17220/2/4, VEN = 0V, TA= +25°C
0.1
Enable Input Impedance
MAX17220/2/4
100
Required Select
Resistor Accuracy
RSEL
Use the nearest ±1% resistor from
RSEL Selection Table
Select Resistor
Detection Time
tRSEL
VOUT = 1.8V, CRSEL < 2pF (Note 9)
IEN_LK
UNITS
nA
MAX17224/5
MAX17221/3/5, VEN = 5.5V, TA = +25°C
Enable Input Leakage
MAX
VLX = 1.5V, TA =
+25°C
-1
360
600
nA
200
kΩ
+1
%
1320
μs
Note 2: Limits are 100% production tested at TA = +25°C. Limits over the operating temperature range are guaranteed through
correlation using statistical quality control (SQC) methods.
Note 3: Guaranteed by the Required Select Resistor Accuracy parameter.
Note 4: Output Accuracy, Low Power mode is the regulation accuracy window expected when IOUT > IOUT_TRANSITION. See PFM
Control Scheme and VOUT ERROR vs ILOAD TOC for more details. This accuracy does not include load, line, or ripple.
Note 5: Output Accuracy, Ultra-Low Power mode is the regulation accuracy window expected when IOUT < IOUT_TRANSITION. See
PFM Control Scheme and VOUT ERROR vs. ILOAD TOC for more details. This accuracy does not include load, line, or ripple.
Note 6: This is a static measurement. See ILIM vs. VIN TOC. The actual peak current limit depends upon VIN and L due to propagation
delays.
Note 7: Guaranteed by measuring LX frequency and duty cycle.
Note 8: This is a static measurement.
Note 9: This is the time required to determine RSEL value. This time adds to the startup time. See the Output Voltage Selection section.
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Analog Devices | 4
MAX17220–MAX17225
400mV to 5.5V Input, nanoPower Synchronous
Boost Converters with True Shutdown
Typical Operating Characteristics
(MAX17222ELT+, IN = 1.5V, OUT = 3V, L = 2.2μH Coilcraft® XFL4020-222, CIN = 10μF, COUT = 10μF, TA = +25°C, unless otherwise
noted.)
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Analog Devices | 5
MAX17220–MAX17225
400mV to 5.5V Input, nanoPower Synchronous
Boost Converters with True Shutdown
Typical Operating Characteristics (continued)
(MAX17222ELT+, IN = 1.5V, OUT = 3V, L = 2.2μH Coilcraft® XFL4020-222, CIN = 10μF, COUT = 10μF, TA = +25°C, unless otherwise
noted.)
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Analog Devices | 6
MAX17220–MAX17225
400mV to 5.5V Input, nanoPower Synchronous
Boost Converters with True Shutdown
Pin Configurations
TOP VIEW
TOP VIEW
+
OUT
LX
GND
MA
MAX1722x
X1722x
+
1
6
MAX1722x
2
5
3
4
EN
A
OUT
LX
GND
B
EN
IN
SEL
1
2
3
IN
SEL
µDFN
WLP
Pin Description
PIN
NAME
FUNCTION
1
OUT
Output Pin. Connect a 10μF X5R ceramic capacitor (minimum 2μF capacitance) to
ground.
A2
2
LX
A3
3
GND
B1
6
EN
Active-High Enable Input. See Supply Current section for recommended
connections.
B2
5
IN
Input Pin. Connect a 10μF X5R ceramic capacitor (minimum 2μF capacitance) to
ground. Depending on the application requirements, more capacitance may be
needed (i.e., Bluetooth® LE).
B3
4
SEL
6 WLP
μDFN
A1
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Switching Node Pin. Connect the inductor from IN to LX.
Ground Pin.
Output Voltage Select Pin. Connect a resistor from SEL to GND based on the
desired output voltage. See the RSEL Selection Table.
Analog Devices | 7
MAX17220–MAX17225
400mV to 5.5V Input, nanoPower Synchronous
Boost Converters with True Shutdown
Functional Diagram
2.2µH
LX
MAX17220/2/3/4/5
IN
CIN
10µF
TRUE
SHUTDOWN
STARTUP
OUT
COUT
10µF
CURRENT
SENSE
MODULATOR
REFERENCE
EN
OPTIONAL
ENABLE PIN
TRANSIENT
PROTECTION
OUTPUT
VOLTAGE
SELECTOR
SEL
RSEL
GND
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Analog Devices | 8
MAX17220–MAX17225
400mV to 5.5V Input, nanoPower Synchronous
Boost Converters with True Shutdown
Detailed Description
The MAX17220–MAX17225 compact, high-efficiency, step-up DC-DC converters have ultra-low quiescent current, are
guaranteed to start up with voltages as low as 0.95V, and operate with an input voltage down to 400mV, depending
on load current. True Shutdown disconnects the input from the output, saving precious battery life. Every detail of the
MAX17220–MAX17225 was carefully chosen to allow for the lowest power and smallest solution size. Such details as
switching frequencies up to 2.5MHz, tiny package options, a single-output setting resistor, 300ns fixed turn-on time, as
well as three current limit options, allow the user to minimize the total solution size.
Supply Current
True Shutdown Current
The total system shutdown current (ISD_TOTAL_SYSTEM) is made up of the MAX17220–MAX17225 total shutdown
current (ISD_TOTAL) and the current through an external pullup resistor, as shown in Figure 1 ISD_TOTAL is listed in the
Electrical Characteristics table and is typically 0.5nA. It is important to note that ISD_TOTAL includes LX and IN leakage
currents. (See the Shutdown Supply Current vs. Temperature graph in the Typical Operating Characteristics section.)
ISD_TOTAL_SYSTEM current can be calculated using the formula below. For example, for the MAX17220–MAX17225
with EN connected to an open-drain GPIO of a microcontroller, a VIN = 1.5V, VOUT = 3V, and a 33MΩ pullup resistor,
ISD_TOTAL_SYSTEM current is 45.9nA.
VIN
1.5
ISD_TOTAL_SYSTEM = ISD_TOTAL + R
= 0.5nA + 33MΩ = 45.9nA
PULLUP
(Figure 1)
Figure 2 shows a typical connection of the MAX17221/MAX17223/MAX17225 to a push-pull microcontroller GPIO.
ISD_TOTAL_SYSTEM current can be calculated using the formula below. For example, a MAX17221/MAX17223/
MAX17225 with EN connected to a push-pull microcontroller GPIO, VIN = 1.5V, and VOUT = 3V, ISD_TOTAL_SYSTEM
current is 0.5nA.
ISD_TOTAL_SYSTEM = ISD_TOTAL = 0.5nA
(Figure 2, Figure 3)
Figure 3 shows a typical connection of the MAX17220/MAX17222/MAX17224 with a pushbutton switch to minimize
the ISD_TOTAL_SYSTEM current. ISD_TOTAL_SYSTEM current can be calculated using the formula above. For example,
a MAX17220/MAX17222/MAX17224 with EN connected as shown in Figure 3, with VIN = 1.5V and VOUT = 3V, the
ISD_TOTAL_SYSTEM current is 0.5nA.
33MΩ
RPULLUP
OUT
IN
GND
MAX17220–
MAX17225
SEL
µC
OPEN-DRAIN
GPIO
LX
OUT
EN
IN
Figure 1. For All Versions, EN Pin Can Be Driven by an Open-Drain Microcontroller GPIO.
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Analog Devices | 9
MAX17220–MAX17225
400mV to 5.5V Input, nanoPower Synchronous
Boost Converters with True Shutdown
IN
OUT
IN
GND
MAX17221/
MAX17223/
MAX17225
VIO
SEL
µC
LX
EN
OUT
Figure 2. Only the MAX17221/MAX17223/MAX17225 EN Pin Can Be Driven by a Push-Pull Microcontroller GPIO.
IN
LX
OUT
IN
EN
OUT
SEL
µC
GPIO
GND
MAX17220/
MAX17222/
MAX17224
33MΩ
Figure 3. The MAX17220/MAX17222/MAX17224 Total System Shutdown Current Will Only Be Leakage if Able to Use Pushbutton as
Shown.
Enable Transient Protection (ETP) Current
The MAX17220/MAX17222/MAX17224 have internal circuitry that helps protect against accidental shutdown by
transients on the EN pin. Once the part is started up, these parts allow the voltage at IN to drop as low as 400mV while still
keeping the part enabled, depending on the load current. This feature comes at the cost of slightly higher supply current
that is dependent on the pullup resistor resistance. The extra supply current for this protection option can be calculated
by the equation below. For example, for the MAX17220/MAX17222/MAX17224 used in the Figure 1 connection, a VIN =
1.5V, VOUT = 3V, a 33MΩ pullup resistor and an 85% efficiency, the IQ_ETP is expected to be 61.3nA.
(VOUT − VIN)
1
VOUT
IQ_ETP = (R
× (η × V
− 1)
PULLUP + 100K)
IN
(Figure 1)
(3V − 1.5V)
1
3V
IQ_ETP = (33M + 100K) × ( 0.85 × 1.5 − 1) = 61.3nA
(Figure 1)
Use the efficiency η from the flat portion of the efficiency typical operating curves while the device is in ultra-lowpower mode (ULPM). See the PFM Control Scheme section for more info on ULPM. Do not use the efficiency for your
actual load current. If you are using the versions of the part without enable input transient protection (using MAX17221/
MAX17223/MAX17225), or if you are using any part version and the electrical path from the EN pin is opened after
startup, then there is no IQ_ETP current and it will be zero.
IQ_ETP = N/A = 0
(Figure 2)
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Analog Devices | 10
MAX17220–MAX17225
400mV to 5.5V Input, nanoPower Synchronous
Boost Converters with True Shutdown
(VOUT)
1
VOUT
IQ_ETP = (R
× (η × V )
PULLUP + 100K)
IN
(Figure 3)
(3V)
1
3V
IQ_ETP = (33M + 100K) × ( 0.85 × 1.5V ) = 213.2nA
(Figure 3)
Quiescent Current
The MAX17221–MAX17225 has ultra-low quiescent current and was designed to operate at low input voltages by
bootstrapping itself from its output by drawing current from the output. Use the equation below to calculate the total
system quiescent current IQ_TOTAL_SYSTEM using the efficiency η from the flat portion of the efficiency graph in the
Typical Operating Characteristics section while the device is in ULPM. See the PFM control scheme section for more info
on ULPM. Do not use the efficiency for your actual load current. To calculate the IQ_ETP for the MAX17220/MAX17222/
MAX17224, see the Enable Transient Protection (ETP) Current section. If you are using the versions of the part without
enable input transient protection (using the MAX17221/MAX17223/MAX17225) or if you are using any part version and
the electrical path from the EN pin is opened after startup, then the IQ_ETP current will be zero. For example, for the
MAX17221/MAX17223/MAX17225, VIN = 1.5V, VOUT = 3V, and an 85% efficiency, the IQ_TOTAL_SYSTEM is 706.4nA.
IQ_TOTAL_SYSTEM = IQ_IN_TOTAL +
IQ_OUT
VIN
η×(
)
VOUT
(MAX17221/3/5)
IQ_TOTAL_SYSTEM = 0.5nA +
300nA
= 706.4nA
1.5V
0.85 × (
)
3V
(MAX17221/3/5)
IQ_TOTAL_SYSTEM = IQ_IN_TOTAL +
IQ_OUT
+ IQ_ETP
VIN
η×(
)
VOUT
(MAX17220/2/4)
(MAX17220/2/4)
IQ_TOTAL_SYSTEM = 0.5nA +
300nA
+ 61.3nA = 767.7nA
1.5V
)
3V
0.85 × (
(MAX17220/2/4)
PFM Control Scheme
The MAX17221–MAX17225 utilizes a fixed on-time, current-limited, pulse-frequency-modulation (PFM) control scheme
that allows ultra-low quiescent current and high efficiency over a wide output current range. The inductor current
is limited by the 0.225A/0.5A/1A N-channel current limit or by the 300ns switch maximum on-time. During each on
cycle, either the maximum on-time or the maximum current limit is reached before the off-time of the cycle begins.
The MAX17221–MAX17225 PFM control scheme allows for both continuous conduction mode (CCM) or discontinuous
conduction mode (DCM). When the error comparator senses that the output has fallen below the regulation threshold,
another cycle begins. See the MAX17221–MAX17225 simplified Functional Diagram.
The MAX17221–MAX17225 automatically switches between the ULPM, low-power mode (LPM) and high-power mode
(HPM), depending on the load current. Figure 4 and Figure 5 show typical waveforms while in each mode. The output
voltage, by design, is biased 2.5% higher while in ULPM so that it can more easily weather a future large load transient.
ULPM is used when the system is in standby or an ultra-low-power state. LPM and HPM are useful for sensitive sensor
measurements or during wireless communications for medium output currents and large output currents respectively. The
user can calculate the value of the load current where ULPM transitions to LPM using the equation below. For example,
for VIN = 1.5V, VOUT = 3V, and L = 2.2μH, the UPLM to LPM transition current happens at approximately 1.49mA and
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Analog Devices | 11
MAX17220–MAX17225
400mV to 5.5V Input, nanoPower Synchronous
Boost Converters with True Shutdown
a no-load frequency of 11.5Hz. The MAX17221–MAX17225 enters HPM when the inductor current transitions from DCM
to CCM.
VOUT
ULTRA-LOW POWER MODE (UPLM): LIGHT LOADS
DCM
VOUT TARGET + 2.5%
LOW POWER MODE (LPM): MEDIUM LOADS
DCM
VOUT TARGETVOUT TARGET - LOAD REG
17.5µs
5µs
CCM
LOAD DEPENDENT
750ns
HIGH POWER MODE (HPM): HEAVY LOADS
TIME
Figure 4. ULPM, LPM, and HPM Waveforms (Part 1)
VOUT
ULTRA LOW POWER MODE (UPLM): LIGHT LOADS
DCM
100ms
VOUT TARGET + 2.5%
LOW POWER MODE (LPM): MEDIUM LOADS
17.5µs
DCM
VOUT TARGETVOUT TARGET - LOAD REG
7µs
CCM
650ns
LOAD DEPENDENT
HIGH POWER MODE (HPM): HEAVY LOADS
TIME
Figure 5. ULPM, LPM, and HPM Waveforms (Part 2)
IOUT_TRANSITION = (
VIN
300ns2
) × (V
2L
OUT
VIN
300ns2
1, 5V
η
−1
) × ( 17.5μs )
0.85
= ( 2 × 2.2μH ) × ( 3V
) × ( 17.5μs ) = 1.49mA
−1
1.5V
The minimum switching frequency can be calculated by the following equation:
1
IQ
fSW(MIN) = 17.5μs × IOUT_TRANSITION
1
300nA
fSW(MIN) = 17.5μs × 1.49mA = 11.5Hz
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Analog Devices | 12
MAX17220–MAX17225
400mV to 5.5V Input, nanoPower Synchronous
Boost Converters with True Shutdown
Operation with VIN > VOUT
If the input voltage (VIN) is greater than the output voltage (VOUT) by a diode drop (VDIODE varies from ~0.2V at light
load to ~0.7V at heavy load), then the output voltage is clamped to a diode drop below the input voltage (i.e., VOUT = VIN
- VDIODE).
When the input voltage is closer to the output voltage target (i.e., VOUT target + VDIODE > VIN > VOUT target) the
MAX17220–MAX17225 operate like a buck converter.
Hot Plugging
The MAX17221–MAX17225 will initiate a controlled soft-start in the event that a supply voltage is reapplied at a high
dV/dt rate; for example, during installation of a fresh battery. While in regulation, if VIN steps abruptly above VOUT for
more than 1V (typ), the device will reset. Output voltage droop in this case will be a function of the load current, output
capacitance, and time required for soft-start to complete, which is 1.5ms (typ).
Design Procedure
Output Voltage Selection
The MAX17221–MAX17225 has a unique single-resistor output selection method known as RSEL, as shown in Figure
6. At startup, the MAX17221–MAX17225 uses up to 200μA only during the select resistor detection time, typically for
600μs, to read the RSEL value. RSEL has many benefits, which include lower cost and smaller size, since only one
resistor is needed versus the two resistors needed in typical feedback connections. Another benefit is that RSEL allows
our customers to stock just one part in their inventory system and use it in multiple projects with different output voltages
just by changing a single standard 1% resistor. Lastly, RSEL eliminates wasting current continuously through feedback
resistors for ultra-low-power battery-operated products. Select the RSEL resistor value by choosing the desired output
voltage in the RSEL Selection Table.
IN
OUT
OUT
LX
IN
EN
EN
SEL
GND
MAX1722X
GND
RSEL
Figure 6. Single RSEL Resistor Sets the Output Voltage
RSEL Selection Table
www.analog.com
VOUT (V)
STD RES 1% (kΩ)
1.8
OPEN
1.9
909
2.0
768
2.1
634
2.2
536
2.3
452
2.4
383
2.5
324
2.6
267
Analog Devices | 13
MAX17220–MAX17225
400mV to 5.5V Input, nanoPower Synchronous
Boost Converters with True Shutdown
2.7
226
2.8
191
2.9
162
3.0
133
3.1
113
3.2
95.3
3.3
80.6
3.4
66.5
3.5
56.2
3.6
47.5
3.7
40.2
3.8
34
3.9
28
4.0
23.7
4.1
20
4.2
16.9
4.3
14
4.4
11.8
4.5
10
4.6
8.45
4.7
7.15
4.8
5.9
4.9
4.99
5.0
SHORT
Inductor Selection
A 2.2μH inductor value provides the best size and efficiency tradeoff in most applications. Smaller inductance values
typically allow for the smallest physical size, and larger inductance values allow for more output current assuming CCM is
achieved. Most applications are expected to use 2.2μH, as shown in the example circuits. For low input voltages, 1μH will
work best. If one of the example application circuits does not provide enough output current, use the equations below to
calculate a larger inductance value that meets the output current requirements, assuming it is possible to achieve. For the
equations below, choose an IIN between 0.9 x ILIM and half ILIM. It is not recommended to use an inductor value smaller
than 1μH or larger than 4.7μH. See the Typical Operating Characteristics section for choosing the value of efficiency η
using the closest conditions for your application. An example calculation has been provided for the MAX17222 that has
ILIM = 500mA, VIN (min) = 1.8V, VOUT = 3V, and a desired IOUT of 205mA, which is beyond one of the 2.2μH example
circuits. The result shows that the inductor value can be changed to 3.3μH to achieve a little more output current.
IIN =
VOUT × IOUT
η × VIN
ILIM
2
3V × 205mA
= 0.85 × 1.8V = 402mA
< IIN < 0.9 × ILIM
ΔI = (ILIM - IIN)× 2 = (500mA - 402mA)× 2 = 196mA
LMIN =
VIN × tON(MAX)
Δl
=
1.8V × 300ns
= 2.76μH
196mA
= > 3.3µH closest standard value
www.analog.com
Analog Devices | 14
MAX17220–MAX17225
400mV to 5.5V Input, nanoPower Synchronous
Boost Converters with True Shutdown
Capacitor Selection
Input capacitors reduce current peaks from the battery and increase efficiency. For the input capacitor, choose a ceramic
capacitor because they have the lowest equivalent series resistance (ESR), smallest size, and lowest cost. Choose an
acceptable dielectric such as X5R or X7R. Other capacitor types can be used as well but will have larger ESR. The
biggest downside of ceramic capacitors is their capacitance drop with higher DC bias and, because of this, at minimum
a standard 10μF ceramic capacitor is recommended at the input for most applications. The minimum recommended
capacitance (not capacitor) at the input is 2μF for most applications. For applications that use batteries that have a
high source impedance greater than 1Ω, more capacitance may be needed. A good starting point is to use the same
capacitance value at the input as for the output.
The minimum output capacitance that ensures stability is 2μF. At minimum, a standard 10μF X5R (or X7R) ceramic
capacitor is recommended for most applications. Due to DC bias effects, the actual capacitance can be 80% lower
than the nominal capacitor value. The output ripple can be calculated with the following equation. For example, for the
MAX17220 and MAX17222–MAX17225 with VIN = 1.5V, VOUT = 3V, an effective capacitance of 5μF, and a capacitor
ESR of 4mΩ, the expected ripple is 7mV.
V_RIPPLE = IL_PEAK × ESR_COUT
1
1
+ 2 IL_PEAK × tOFF × C
OUT(effective)
Where,
VIN
1.5V
IL_PEAK = L × tON = 2.2μH × 300ns = 204mA
tOFF = tON[ V
VIN
OUT − VIN
1.5V
] = 300ns × [ 3V − 1.5V ] = 300ns
COUT (effective) = 5μF, ESR_COUT for Murata GRM155R61A106ME44 is 4mΩ from 200kHz to 2MHz.
1
1
V_RIPPLE = 204mA × 4mΩ + 2 × 204mA × 300ns × 5μF = 7mV
PCB Layout Guidelines
Careful PC board layout is especially important in nanocurrent DC-DC converters. In general, minimize trace lengths to
reduce parasitic capacitance, parasitic resistance, and radiated noise. Remember that every square of 1oz copper will
result in 0.5mΩ of parasitic resistance. The connection from the bottom of the output capacitor and the ground pin of the
device must be extremely short, as should be that of the input capacitor. Keep the main power path from IN, LX, OUT,
and GND as tight and short as possible. Minimize the surface area used for LX since this is the noisiest node. Lastly, the
trace used for RSEL should not be too long nor produce a capacitance of more than a few picofarads.
www.analog.com
Analog Devices | 15
MAX17220–MAX17225
400mV to 5.5V Input, nanoPower Synchronous
Boost Converters with True Shutdown
Applications Information
Primary Cell Bluetooth Low Energy (Bluetooth LE) Temperature Sensor Wearable
OPTIONAL LDO
400mV* TO 1.6V
2.75V
3V
MAX30205
MEDICAL GRADE
TEMP SENSOR
MAX1725
LDO
MAX1722X
BOOST
BATTERY
SILVER OXIDE
ZINC AIR
AAAA
AAA
AA
I2C PORT
Arm®
Cortex®
M4
*LOAD CURRENT DEPENDENT
3V
LP BLUETOOTH
LE/NFC µC WITH
INTERNAL BUCK
DC-DC
BUCK
1.3V
BLUETOOTH
LE RADIO
FLASH
RAM
NFC
GND
Figure 7. MAX1722x/MAX30205 Temperature Sensor Wearable Solution
www.analog.com
Analog Devices | 16
MAX17220–MAX17225
400mV to 5.5V Input, nanoPower Synchronous
Boost Converters with True Shutdown
Primary Cell Bluetooth LE Optical Heart Rate Monitoring (OHRM) Sensor Wearable
0.8V TO 1.6V
3.3V LED SUPPLY
(OR ADJ TO 5V)
BATTERY
SILVER OXIDE
ZINC AIR
AAAA
AAA
AA
I2C PORT
ARM
CORTEX
M4
LP BLUETOOTH
LE/NFC µC WITH
INTERNAL BUCK
3.3V
3.6V MAX
1.3V
DC-DC
BUCK
BLUETOOTH
LE RADIO
FLASH
RAM
NFC
GND
Figure 8. MAX1722x/MAX30110/MAX30101/MAX30102 Optical Heart Rate Monitor (OHRM) Sensor Wearable Solution for Primary
Cells
Secondary Rechargeable Lithium Cell Bluetooth LE Optical Heart Rate Monitor (OHRM) Sensor
Wearable
2.7V TO 4.2V
4.5V
5V
OR
ADJ
BATTERY
Li+
MAX32625/26
MAX32620/21
I2C
µC
Figure 9. MAX1722x/MAX30110/MAX30101/MAX30102 Optical Heart Rate Monitor (OHRM) Sensor Wearable Solution for
Secondary Cells
www.analog.com
Analog Devices | 17
MAX17220–MAX17225
400mV to 5.5V Input, nanoPower Synchronous
Boost Converters with True Shutdown
Supercapacitor Backup Solution for RTC Preservation
REGULATE WITH SUPERCAP DOWN TO 400mV
2.3V TO 5.5V
SOURCE
V CAP= 400mV TO 5.5V
3.3V
SUPERCAP
REVERSE CURRENT BLOCKING
VCAP = 5V TO 3.8V V OUT = V CAP - V DIODE
VCAP = 3.8V TO 400mV V OUT = 3.3V
Figure 10. MAX1722x/MAX14575/DS1341 RTC Backup Solution
Supercapacitor Backup Solution to Maintain Uniform Sound for Alarm Beeper Buzzers
UNIFORM ALARM WITH SUPERCAP DOWN TO 400mV*
2.3V TO 5.5V
SOURCE
VCAP= 400mV TO 5.5V
5V
SUPERCAP
REVERSE CURRENT BLOCKING
V OUT = 5V
V CAP = 5.5V TO 400mV*
*LOAD DEPENDENT
Figure 11. MAX1722x/MAX14575 Solution for Alarm Beeper Buzzers
www.analog.com
Analog Devices | 18
MAX17220–MAX17225
400mV to 5.5V Input, nanoPower Synchronous
Boost Converters with True Shutdown
Zero Reverse Current in True Shutdown for Multisource Applications
ZERO REVERSE CURRENT IN SHUTDOWN
2.7V TO 4.2V
ILOAD
0μA
5V
SOLAR CELLS
0μA
SUPERCAP
BATTERY
Li+
0μA
Figure 12. MAX1722x Has Zero Reverse Current in True Shutdown
Typical Application Circuits
Smallest Solution Size—0603 Inductor—MAX17222/MAX17223 500mA ILIM (Part 1)
IN
1.8V TO 3V
RSEL
L1 1µH/0603 MURATA DFE160808S -1R0M
CIN 10µF/0402/X5R/6.3V MURATA GRM155R60J106ME44
COUT 10µF/0402/X5R/10V MURATA GRM155R61A106ME44
3.3V OUTPUT R SEL 80.6kΩ ±1%
3V OUTPUT R SEL 133kΩ ±1%
www.analog.com
OUT
MAX17222
MAX17223
GND
GND
SEL
STARTUP
0.88 (TYP)
COUT
10µF
EN
OUT
3.3V, 160mA
3V, 185mA
COUT
10µF
GND
MAX17222
MAX17223
GND
3.3V, 16mA
3V, 20mA
IN
LX
OUT
IN
EN
EN
L1 2.2µH
CIN
10µF
LX
OUT
CIN
10µF
EN
L1 1µH
SEL
IN
0.8V TO 3V
RSEL
L1 2.2µH/0603 MURATA DFM18PAN2R2MG0L
CIN 10µF/0402/X5R/6.3V MURATA GRM155R60J106ME44
COUT 10µF/0402/X5R/10V MURATA GRM155R61A106ME44
3.3V OUTPUT R SEL 80.6kΩ ±1%
3V OUTPUT R SEL 133kΩ ±1%
Analog Devices | 19
MAX17220–MAX17225
400mV to 5.5V Input, nanoPower Synchronous
Boost Converters with True Shutdown
Typical Application Circuits (continued)
Smallest Solution Size—0603 Inductor—MAX17222/MAX17223 500mA ILIM (Part 2)
IN
2.7V TO 4.2V
L1 2.2µH
OUT
IN
5V, 160mA
3.3V*, 250mA
MAX17222
MAX17223
COUT
10µF
SEL
GND
GND
GND
SEL
STARTUP
0.88 (TYP)
COUT
10µF
EN
LX
LX
MAX17222
MAX17223
GND
CIN
10µF
2V, 90mA
1.8V, 100mA
OUT
IN
EN
EN
L1 2.2µH
OUT
OUT
CIN
10µF
EN
IN
0.8V TO 1.8V
RSEL
RSEL
* = IN < OUT
L1 2.2µH/0603 MURATA MFD160810 -2R2M
CIN 10µF/0402/X5R/6.3V MURATA GRM155R60J106ME44
COUT 10µF/0402/X5R/10V MURATA GRM155R61A106ME44
2V OUTPUT R SEL 768kΩ ±1%
1.8V OUTPUT R SEL OPEN (NO RESISTOR)
L1 2.2µH/0603 MURATA MFD160810 -2R2M
CIN 10µF/0402/X5R/6.3V MURATA GRM155R60J106ME44
COUT 10µF/0402/X5R/10V MURATA GRM155R61A106ME44
5V OUTPUT R SEL SHORT TO GND (NO RESISTOR)
3.3V OUTPUT R SEL 80.6kΩ ±1%
Highest Efficiency Solution—4mm x 4mm Inductor—MAX17222/MAX17223 500mA ILIM (Part 1)
IN
1.8V TO 3V
MAX17222
MAX17223
3.3V, 185mA
3V, 200mA
OUT
MAX17222
MAX17223
GND
SEL
SEL
STARTUP
0.88 (TYP)
COUT
10µF
EN
GND
GND
OUT
CIN
10µF
3.3V,18mA
3V, 22mA
OUT
LX
IN
EN
EN
COUT
10µF
GND
CIN
10µF
L1 2.2µH
LX
OUT
IN
L1 1µH
EN
IN
0.8V TO 3V
RSEL
RSEL
L1 1µH/4X4X2.1MM COILCRAFT XFL4020-102
CIN 10µF/0402/X5R/6.3V MURATA GRM155R60J106ME44
COUT 10µF/0402/X5R/10V MURATA GRM155R61A106ME44
3.3V OUTPUT RSEL 80.6kΩ ±1%
3V OUTPUT RSEL 133kΩ ±1%
L1 2.2µH/4X4X2.1MM COILCRAFT XFL4020-222
CIN 10µF/0402/X5R/6.3V MURATA GRM155R60J106ME44
COUT 10µF/0402/X5R/10V MURATA GRM155R61A106ME44
3.3V OUTPUT RSEL 80.6kΩ ±1%
3V OUTPUT RSEL 133kΩ ±1%
Highest Efficiency Solution—4mm x 4mm Inductor—MAX17222/MAX17223 500mA ILIM (Part 2)
IN
2.7V TO 4.2V
MAX17222
MAX17223
SEL
STARTUP
0.88 (TYP)
COUT
10µF
RSEL
OUT
EN
MAX17222
MAX17223
GND
GND
GND
2V, 115mA
1.8V,120mA
OUT
CIN
10µF
5V, 185mA
3.3V*, 285mA
COUT
10µF
GND
LX
OUT
IN
EN
EN
IN
CIN
10µF
L1 2.2µH
LX
OUT
EN
L1 2.2µH
SEL
IN
0.8V TO 1.8V
RSEL
* = IN < OUT
L1 2.2µH/4X4X2.1MM COILCRAFT XFL4020 -222
CIN 10µF/0402/X5R/6.3V MURATA GRM155R60J106ME44
COUT 10µF/0402/X5R/10V MURATA GRM155R61A106ME44
2V OUTPUT R SEL 768kΩ ±1%
1.8V OUTPUT R SEL OPEN (NO RESISTOR)
www.analog.com
L1 2.2µH/4X4X3MM WURTH 74438357022CIN
CIN 10µF/0402/X5R/6.3V MURATA GRM155R60J106ME44
COUT 10µF/0402/X5R/10V MURATA GRM155R61A106ME44
5V OUTPUT R SEL SHORT TO GND (NO RESISTOR)
3.3V OUTPUT R SEL 80.6kΩ ±1%
Analog Devices | 20
MAX17220–MAX17225
400mV to 5.5V Input, nanoPower Synchronous
Boost Converters with True Shutdown
Ordering Information
PART NUMBER
TEMPERATURE
RANGE
PINPACKAGE
INPUT PEAK CURRENT
IPEAK
TRUE
SHUTDOWN
ENABLE TRANSIENT
PROTECTION
(ETP)
MAX17220ENT+
-40°C to +85°C
6 WLP
225mA
Yes
Yes
MAX17221ENT+
-40°C to +85°C
6 WLP
225mA
Yes
No
MAX17222ENT+
-40°C to +85°C
6 WLP
0.5A
Yes
Yes
MAX17223ENT+
-40°C to +85°C
6 WLP
0.5A
Yes
No
MAX17224ENT+
-40°C to +85°C
6 WLP
1A
Yes
Yes
MAX17225ENT+
-40°C to +85°C
6 WLP
1A
Yes
No
MAX17220ELT+
-40°C to +85°C
6 μDFN
225mA
Yes
Yes
MAX17221ELT+T
-40°C to +85°C
6 μDFN
225mA
Yes
No
MAX17221ELT+
-40°C to +85°C
6 μDFN
225mA
Yes
No
MAX17222ELT+
-40°C to +85°C
6 μDFN
0.5A
Yes
Yes
MAX17223ELT+
-40°C to +85°C
6 μDFN
0.5A
Yes
No
MAX17224ELT+
-40°C to +85°C
6 μDFN
1A
Yes
Yes
MAX17225ELT+
-40°C to +85°C
6 μDFN
1A
Yes
No
MAX17220ALT+
-40°C to +125°C
6 μDFN
225mA
Yes
Yes
MAX17222ALT+
-40°C to +125°C
6 μDFN
500mA
Yes
Yes
MAX17223ALT+
-40°C to +125°C
6 μDFN
500mA
Yes
No
MAX17224ALT+
-40°C to +125°C
6 μDFN
1A
Yes
Yes
MAX17225ALT+
-40°C to +125°C
6 μDFN
1A
Yes
No
+Denotes a lead(Pb)-free/RoHS-compliant package.
T = Tape and reel.
www.analog.com
Analog Devices | 21
MAX17220–MAX17225
400mV to 5.5V Input, nanoPower Synchronous
Boost Converters with True Shutdown
Revision History
REVISION
NUMBER
REVISION
DATE
PAGES
CHANGED
0
2/17
Initial release
1
4/17
Updated Electrical Characteristics and Ordering Information tables and added Operation
with VIN > VOUT section
2
5/17
Removed MAX17221 part number, general data sheet updates
3
7/17
Updated Shutdown Current into IN and Total Shutdown Current into IN LX conditions, Note
5, TOC 5, True Shutdown Current section, Figure 10, added TOC 18, removed future
product references (MAX17220ENT+, MAX17224ENT+, MAX17220ELT+,
MAX17223ELT+, and MAX17224ELT+)
3–5, 7, 10,
18, 22
4
2/19
Updated Absolute Maximum Ratings, Electrical Characteristics, Detailed Description, and
Ordering Information
2–4, 13, 22
5
12/19
Added MAX17221 part number to data sheet
6
10/20
Updated Detailed Description, Ordering Information
7
7/21
Updated Absolute Maximum Ratings
2
8
10/21
Updated Electrical Characteristics table
3
DESCRIPTION
—
3, 8, 13,
19, 21
1–23
1–23
14, 15, 22
Information furnished by Analog Devices is believed to be accurate and reliable. However, no responsibility is
assumed by Analog Devices for its use, nor for any infringements of patents or other rights of third parties that may
result from its use. Specifications subject to change without notice. No license is granted by implication or otherwise
under any patent or patent rights of Analog Devices. Trademarks andregistered trademarks are the property of
their respective owners.
w w w . a n a l o g . c o m
Analog Devices | 22
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