EVALUATION KIT AVAILABLE
Click here to ask about the production status of specific part numbers.
MAX77827
5.5V Input, 1.8A/3.1A Switch Buck-Boost
Converter with 6μA IQ
General Description
Benefits and Features
The MAX77827 is a high-efficiency buck-boost regulator
targeted for one-cell Li-ion powered applications with the
lowest typical quiescent current in the industry of 6μA. It
supports input voltages of 1.8V to 5.5V and an output voltage range of 2.3V to 5.3V. The IC provides two different
switching current levels (1.8A and 3.1A) to optimize external component sizing based on given load current requirements. With the 1.8A switching current-limit option,
the IC can support up to 1.0A load current in buck mode
and 900mA in boost mode (VIN = 3.0V, VOUT = 3.3V).
● 1.8V to 5.5V Input Voltage Range
● 2.3V to 5.3V Single Resistor Adjustable Output
Voltage
● 1.6A Maximum Output Current (3.1A ILIM Option,
Buck Mode)
● 900mA Maximum Output Current (1.8A ILIM Option,
Boost Mode 3.0VIN, 3.3VOUT)
● 96% Peak Efficiency (3.3VIN, 3.3VOUT)
● SKIP Mode for Higher Light-Load Efficiency
● 6μA Ultra-Low Typical Quiescent Current (At TJ =
+25°C)
● 2.5MHz Nominal Switching Frequency
● Enable Pin
● GPIO Pins for System Design Convenience
• FPWM (Forced PWM) Mode Selection Pin
• POK Indicator Pin
The peak efficiency of 96% makes the IC one of the best
solutions as a DC/DC converter to supply a rail for batterypowered portable applications.
The IC features an adjustable output voltage, which can
be programmed from 2.3V to 5.3V through a single resistor. Two GPIO pins are available to support force PWM
enable function and power-OK (POK) indicator. A unique
control algorithm allows high-efficiency, outstanding line/
load transient response, and seamless transition between
buck and boost modes. These options provide design flexibility that allow the IC to cover a wide range of applications and use cases while minimizing board space.
● UVLO, Soft-Start, Active-Output Discharge,
Overcurrent, and Thermal Shutdown Protections
● 1.61mm x 2.01mm, 12-Bump WLP
● 2.5mm x 2.5mm, 14-Lead FC2QFN
Ordering Information appears at end of data sheet.
The MAX77827 is available in a 1.61mm x 2.01mm,
12-bump wafer-level package (WLP), and a 2.5mm x
2.5mm, 14-lead FC2QFN package.
Applications
●
●
●
●
1-Cell Li+ Battery Powered Equipment
Smartphones/Portable/Wearables
Internet of Things (IoT) Devices
LPWAN (LTE/NB-IoT, LTE/Cat-M1)
Simplified Block Diagram
L
1μH
MAX77827
OUT
COUT
22μF
OUTS
FPWM ENABLE
FPWM
EN
POWER-OK
POK
CBIAS
1μF
BIAS
VOUT
2.3V TO 5.3V
L
2012
SEL
AGND
PGND
4.00mm
RSEL*
*CHOOSE RSEL VALUE BASED ON VOUT, SEE TABLE 2
19-100546; Rev 5; 8/21
COUT
0603
LX2
RSEL
LX1
CIN
0603
ENABLE
IN
3.63mm
CIN
10μF
CBIAS
14.52mm2 SOLUTION SIZE
1.8V TO 5.5V
DC SOURCE
MAX77827
5.5V Input, 1.8A/3.1A Switch Buck-Boost
Converter with 6μA IQ
TABLE OF CONTENTS
General Description . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1
Applications . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1
Benefits and Features . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1
Simplified Block Diagram . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1
Absolute Maximum Ratings . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6
Package Information . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6
12 WLP . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6
14 FC2QFN . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6
Electrical Characteristics . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7
Typical Operating Characteristics . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9
Pin Configurations . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12
12 WLP . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12
14 FC2QFN . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12
Pin Description . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13
Functional Diagrams . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13
Function Diagram . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13
Detailed Description . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 14
Start Up . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 14
Immediate Shutdown Conditions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15
Power Down . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15
Buck-Boost Regulator . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15
Buck-Boost Control Scheme . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15
Output Voltage Configuration . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 16
FPWM Mode Enable . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 17
Power-OK (POK) Indicator . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 17
Protection Features . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 17
Undervoltage Lockout (UVLO) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 17
Soft-Start . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 17
Output Active Discharge . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 18
Overcurrent Protection (OCP) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 18
Thermal Shutdown . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 18
Applications Information . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 19
Inductor Selection . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 19
Input Capacitor Selection . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 19
Output Capacitor Selection . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 19
PCB Layout Guidelines . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 20
Typical Application Circuits . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 21
Typical Application Circuit . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 21
Ordering Information . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 22
www.maximintegrated.com
Maxim Integrated | 2
MAX77827
5.5V Input, 1.8A/3.1A Switch Buck-Boost
Converter with 6μA IQ
TABLE OF CONTENTS (CONTINUED)
Revision History . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 23
www.maximintegrated.com
Maxim Integrated | 3
MAX77827
5.5V Input, 1.8A/3.1A Switch Buck-Boost
Converter with 6μA IQ
LIST OF FIGURES
Figure 1. Start-Up Waveform . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 14
Figure 2. Buck-Boost H-Bridge Topology . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 16
Figure 3. Short-Circuit Waveform . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 18
Figure 4. PCB Layout Example (WLP—B and D Options) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 20
Figure 5. PCB Layout Example (FC2QFN—B and D Options) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 21
www.maximintegrated.com
Maxim Integrated | 4
MAX77827
5.5V Input, 1.8A/3.1A Switch Buck-Boost
Converter with 6μA IQ
LIST OF TABLES
Table 1. ILIM Levels . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 14
Table 2. RSEL Selection Table . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 16
Table 3. Inductor Recommendations . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 19
www.maximintegrated.com
Maxim Integrated | 5
MAX77827
5.5V Input, 1.8A/3.1A Switch Buck-Boost
Converter with 6μA IQ
Absolute Maximum Ratings
IN, OUT, BIAS to PGND ........................................... -0.3V to +6V
PGND to AGND ..................................................... -0.3V to +0.3V
EN, SEL, FPWM, POK to AGND ................-0.3V to VBIAS + 0.3V
FB to AGND................................................ -0.3V to VOUT + 0.3V
LX1 to PGND ......................................................... -0.3V to +6.0V
LX2 to PGND ......................................................... -0.3V to +6.0V
IN, LX1, LX2, OUT Continuous RMS current ....................... 1.6A
Operating Junction Temperature Range ............ -40°C to +125°C
Maximum Junction Temperature ...................................... +150°C
Storage Temperature Range ..............................-65°C to +150°C
Soldering Temperature (reflow) ........................................ +260°C
Continuous Power Dissipation
WLP Package (TA = +70°C, derate 13.73mW/°C above
+70°C) ......................................................................1098.4mW
FC2QFN Package (TA = +70°C, derate 15.77mW/°C above
+70°C) ......................................................................1261.8mW
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
12 WLP
Package Code
W121H2+1
Outline Number
21-100302
Land Pattern Number
Refer to Application Note 1891
Thermal Resistance, Four-Layer Board:
Junction to Ambient (θJA)
72.82 C°/W
Junction to Case (θJC)
N/A
14 FC2QFN
Package Code
F142A2F+1
Outline Number
21-100382
Land Pattern Number
90-100127
Thermal Resistance, Four-Layer Board:
Junction to Ambient (θJA)
63.4°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.
www.maximintegrated.com
Maxim Integrated | 6
MAX77827
5.5V Input, 1.8A/3.1A Switch Buck-Boost
Converter with 6μA IQ
Electrical Characteristics
(VIN = 3.8V, VOUT = 3.3V, typicals are at TA ≈ TJ = +25°C. Limits are 100% production tested at TJ = +25°C. Limits over the operating
temperature range (TJ = -40°C to +125°C) are guaranteed by design and characterization, unless otherwise noted.)
PARAMETER
SYMBOL
CONDITIONS
MIN
TYP
MAX
UNITS
GENERAL
Input Voltage Range
Shutdown Supply
Current
Input Supply Current
Active Discharge
Resistance
Thermal Shutdown
VIN
For A and D options
1.8
5.5
For B and C options
2.6
5.5
0.1
2
EN = Low, TJ = -40°C to +125°C (Note 2)
3
8
IQ_SKIP
SKIP mode, no switching
6
14
µA
IQ_PWM
FPWM mode, no load, no switching
2
6
mA
ISHDN
EN = Low, TJ = +25°C
V
RDISCHG
µA
100
Ω
165
°C
TSHDN
Rising, +20°C hysteresis
VOUT
External resistor programmable
2.3
5.3
PWM mode, TJ = +25°C
-1
+1
PWM mode, TJ = -40°C to +125°C
-2
+2
SKIP mode, no load, TJ = +25°C
-1
H-BRIDGE
Output Voltage Range
Output Voltage
Accuracy
VOUT_ACC1
VOUT_ACC2
V
%
+4.5
VIN = 1.8V to 5.5V (for A and D options)
0.4
VIN = 2.6V to 5.5V (for B and C options)
0.4
Load Regulation
Note 1
0.25
%/A
Line Transient
Response
VOS1/VUS1
IOUT = 0.5A, VIN changes from 3.4V to
2.9V in 25µs (20mV/µs), L = 1µH,
COUT_NOM = 8µF (Note 1)
50
mV
Load Transient
Response
VOS2/VUS2
IOUT changes from 10mA to 0.5A in
15µs, L = 1µH, COUT_NOM = 8µF (Note
1)
250
mV
Line Regulation
LX1/2 Current Limit
ILIM_LX
%/V
TJ = -40°C to +125°C, for A and C
options
2.5
3.1
3.7
TJ = -40°C to +125°C, for B and D
options
1.3
1.8
2.3
A
High-Side PMOS On
Resistance
RDSON_P
ILX = 100mA per switch
10
130
mΩ
Low-Side NMOS On
Resistance
RDSON_N
ILX = 100mA per switch
15
110
mΩ
Switching Frequency
fSW
PWM mode, TJ = +25°C
2.25
2.5
2.75
PWM mode, TJ = -40°C to +125°C
2.2
2.5
2.8
Turn-On Delay Time
tON_DLY
SEL Detection Time
tSEL
www.maximintegrated.com
MHz
From EN asserting to SEL detection
(Note 2)
100
µs
After turn-on delay to LX switching (Note
2)
600
µs
Maxim Integrated | 7
MAX77827
5.5V Input, 1.8A/3.1A Switch Buck-Boost
Converter with 6μA IQ
Electrical Characteristics (continued)
(VIN = 3.8V, VOUT = 3.3V, typicals are at TA ≈ TJ = +25°C. Limits are 100% production tested at TJ = +25°C. Limits over the operating
temperature range (TJ = -40°C to +125°C) are guaranteed by design and characterization, unless otherwise noted.)
PARAMETER
Soft-Start Time
Minimum Effective
Output Capacitance
LX1, LX2 Leakage
Current
SYS UndervoltageLockout Threshold
SYMBOL
tSS
CEFF_MIN
ILK_85
VUVLO_R
VUVLO_F
CONDITIONS
After SEL detection
to soft-start timer
finish
MIN
TYP
IOUT = 10mA (Note
1), for B and D
options
1500
IOUT = 10mA (Note
1), for A and C
options
200
MAX
UNITS
µs
0A < IOUT < 1A
8
VLX1/2 = 0V or 5.5V, VOUT = 5.5V, VIN =
5.5V, TJ = +85°C
0.1
µF
2
SYS rising, options B and C
2.4
2.5
2.6
SYS rising, options A and D
1.70
1.75
1.80
SYS falling, options B and C
1.9
2.05
2.2
SYS falling, options A and D
1.62
1.68
1.74
µA
V
ENABLE INPUT (EN)
EN Logic-Low Threshold
VEN_L
EN Logic-High
Threshold
VEN_H
0.4
1.3
V
V
FPWM INPUT
FPWM Logic-Low
Threshold
VIL
FPWM Logic-High
Threshold
VIH
FPWM Internal
Pulldown Resistance
RPD
0.4
1.3
Pulldown resistor to GND
400
V
V
800
1600
kΩ
0.4
V
+1
µA
POK OUTPUT
POK Output Low
Voltage
VPOK_L
ISINK = 1mA
POK Output High
Leakage
IPOK_25C
TJ = +25°C
-1
IPOK_R
VOUT rising, expressed as a percentage
of VOUT
92.5
IPOK_F
VOUT falling, expressed as a percentage
of VOUT
90
POK Threshold
%
Note 1: Guaranteed by ATE characterization. Not directly tested in production.
Note 2: Guaranteed by design. Production tested through scan.
www.maximintegrated.com
Maxim Integrated | 8
MAX77827
5.5V Input, 1.8A/3.1A Switch Buck-Boost
Converter with 6μA IQ
Typical Operating Characteristics
(VIN = 3.8V, VOUT = 3.3V, L = 1μH (Coilcraft XAL4020-102ME), Skip Mode, ILIM_LX = 1.8A, TA = +25°C, unless otherwise noted.)
www.maximintegrated.com
Maxim Integrated | 9
MAX77827
5.5V Input, 1.8A/3.1A Switch Buck-Boost
Converter with 6μA IQ
Typical Operating Characteristics (continued)
(VIN = 3.8V, VOUT = 3.3V, L = 1μH (Coilcraft XAL4020-102ME), Skip Mode, ILIM_LX = 1.8A, TA = +25°C, unless otherwise noted.)
www.maximintegrated.com
Maxim Integrated | 10
MAX77827
5.5V Input, 1.8A/3.1A Switch Buck-Boost
Converter with 6μA IQ
Typical Operating Characteristics (continued)
(VIN = 3.8V, VOUT = 3.3V, L = 1μH (Coilcraft XAL4020-102ME), Skip Mode, ILIM_LX = 1.8A, TA = +25°C, unless otherwise noted.)
www.maximintegrated.com
Maxim Integrated | 11
MAX77827
5.5V Input, 1.8A/3.1A Switch Buck-Boost
Converter with 6μA IQ
Pin Configurations
12 WLP
TOP VIEW
(BUMP SIDE DOWN)
MAX77827
1
2
3
4
A
LX1
IN
BIAS
AGND
B
PGND
FPWM
POK
SEL
C
LX2
OUT
OUTS
EN
+
12 WLP
(1.61mm x 2.01mm, 0.4mm PITCH)
14 FC2QFN
1
POK
2
EN
3
14
13
OUT
SEL
OUTS
+
FPWM
TOP VIEW
11
12
10 LX2
9 PGND
MAX77827
8
5
AGND
BIAS
7
6
IN
4
LX1
14 FC2
FC2QFN
QFN
(2.5
2.5mm
mm x 2.5mm x 0.55mm PITCH)
www.maximintegrated.com
Maxim Integrated | 12
MAX77827
5.5V Input, 1.8A/3.1A Switch Buck-Boost
Converter with 6μA IQ
Pin Description
PIN
12 WLP
NAME
14 FC2QFN
FUNCTION
TYPE
A1
8
LX1
A2
6, 7
IN
Switching Node 1
Power
Input. Bypass to PGND with a 10V 10μF capacitor.
Power
A3
5
BIAS
Internal Bias. Bypass to PGND with a 10V 1μF capacitor.
Analog
A4
4
AGND
Analog Ground
Ground
B1
9
PGND
Power Ground
B2
14
FPWM
FPWM Mode Selection (active-high)
Ground
B3
2
POK
Power-OK Open-Drain Output (active-high)
Digital Input
Digital Output
B4
1
SEL
Select the output voltage with resistor (see Table 2).
Analog
C1
10
LX2
Switching Node 2
Power
C2
11, 12
OUT
Output. Bypass to PGND with a 10V 22μF capacitor.
Power
C3
13
OUTS
Output Sense
Analog
C4
3
EN
Enable Pin
Digital Input
Functional Diagrams
Function Diagram
LX1
LX2
IN
OUT
UVLO
CS2
CS1
CS2
ILIM_PEAK
OCP
BIAS
PGND
MAX77827
OUT
ACTIVE
DISCHARGE
LOGIC
CONTROL
EN
FPWM
OUTS
POK
SLOPE
COMPENSATION
POK
TSHDN
COMP
CS1/CS2
EAMP
SOFTSTART
REF
TARGET
OUTPUT
SELECTOR
SEL
AGND
www.maximintegrated.com
Maxim Integrated | 13
MAX77827
5.5V Input, 1.8A/3.1A Switch Buck-Boost
Converter with 6μA IQ
Detailed Description
Start Up
When the EN pin is set to high, the IC turns on the internal bias circuitry which takes typically 100µs (tON_DLY) to settle.
After the internal bias circuitry is settled, the controller senses the SEL pin resistance to set the reference voltage. The
RSEL reading takes about 600µs (typ). After the IC reads the RSEL value, it begins the soft-start process. During the
soft-start process, the IC lowers the ILIM level from normal ILIM level and ramps the output voltage. This prevents the
buck-boost from drawing too much current from the input supply during start up. The soft-start process takes 1.5ms (typ)
for options B and D, and takes 200µs (typ) for options A and C.
EN
VOUT
TON_DLY
TSEL
TSS
ILIM
ILIM_SS
IL
Figure 1. Start-Up Waveform
The buck-boost is in FPWM mode for the entire duration of TSS. Current limit during soft-start (ILIM_SS) increases to ILIM
after approximately half of TSS. See Table 1 for a list of parts with their respective soft-start and normal operation ILIM
levels.
Table 1. ILIM Levels
PART NUMBER
ILIM_SS (A)
ILIM (A)
MAX77827BEWC+T, MAX77827BEFD+T, MAX77827DEWC+T, MAX77827DEFD+T
1.15
1.8
MAX77827AEWC+T, MAX77827AEFD+T, MAX77827CEWC+T, MAX77827CEFD+T
1.8
3.1
www.maximintegrated.com
Maxim Integrated | 14
MAX77827
5.5V Input, 1.8A/3.1A Switch Buck-Boost
Converter with 6μA IQ
Immediate Shutdown Conditions
The following events immediately shutdown the buck-boost:
● Thermal Protection (TJ > +165°C)
● VSYS < SYS UVLO Falling Threshold (VUVLO_F)
The events in this category shutdown the output until fault conditions are removed from the system.
Power Down
When EN pin is set to low, the IC stops switching and turns on the discharge switches until the output is discharged.
Buck-Boost Regulator
The IC buck-boost regulator utilizes a four-switch H-bridge configuration to realize buck and boost operating modes. This
topology maintains output voltage regulation when the input voltage is greater than, equal to, or less than the output
voltage. The buck-boost is ideal in one-cell Li-ion battery powered applications and two-cell Alkaline battery powered
applications, providing 2.3V to 5.3V of output voltage range. High-switching frequency and a unique control algorithm
allow for the smallest solution size, low output noise, and the highest-efficiency across a wide input voltage and output
current range.
Buck-Boost Control Scheme
The buck-boost converter operates using a 2.5MHz fixed-frequency pulse-width modulated (PWM) control scheme with
current-mode compensation. The buck-boost utilizes an H-bridge topology using a single inductor and output capacitor.
The H-bridge topology has three switching phases. See Figure 2 for details.
● Φ1 Switch period (Phase 1: HS1 = ON, LS2 = ON) stores energy in the inductor. Inductor current ramps up at a rate
proportional to the input voltage divided by inductance: VIN/L.
● Φ2 Switch period (Phase 2: HS1 = ON, HS2 = ON) ramps inductor current up or down depending on the differential
voltage across the inductor: (VIN – VOUT)/L.
● Φ3 Switch period (Phase 3: LS1 = ON, HS2 = ON) ramps inductor current down at a rate proportional to the output
voltage divided by inductance: (-VOUT/L).
Boost operation (VIN < VOUT) utilizes phase 1 and phase 2 within a single clock period. See the representation of inductor
current waveform for boost mode operation in Figure 2.
Buck operation (VIN > VOUT) utilizes phase 2 and phase 3 within a single clock period. See the representation of inductor
current waveform for buck mode operation in Figure 2.
www.maximintegrated.com
Maxim Integrated | 15
MAX77827
5.5V Input, 1.8A/3.1A Switch Buck-Boost
Converter with 6μA IQ
BUCK OPERATION
BUCK-BOOST H-BRIDGE
TOPOLOGY
IN
Ф2
OUT
Ф2
Ф3
HS1
Ф2
CHARGE/DISCHARGE L
TSW
HS2
TSW
CLK
CLK
CLK
BOOST OPERATION
L
LS1
Ф3
Ф3
DISCHARGE L
LS2
Ф1
CHARGE L
Ф1
Ф2
Ф1
Ф2
TSW
CLK
TSW
CLK
CLK
Figure 2. Buck-Boost H-Bridge Topology
Output Voltage Configuration
The IC allows a SEL pin to configure the output voltage. Resistors with 1% tolerance (or better) should be chosen, with
nominal values specified in Table 2.
Table 2. RSEL Selection Table
www.maximintegrated.com
RSEL (kΩ)
VOUT (V)
909
2.3
768
2.4
634
2.5
536
2.6
452
2.7
383
2.8
324
2.8
267
2.85
191
2.9
133
3
113
3
95.3
3.1
80.6
3.15
66.5
3.15
Maxim Integrated | 16
MAX77827
5.5V Input, 1.8A/3.1A Switch Buck-Boost
Converter with 6μA IQ
Table 2. RSEL Selection Table (continued)
RSEL (kΩ)
VOUT (V)
56.2
3.2
Open
3.3
Short to GND
3.3
47.5
3.4
40.2
3.45
34
3.5
28
3.6
23.7
3.7
20
3.75
16.9
3.8
14
3.9
11.8
4
10
4.1
8.45
4.2
7.15
4.4
5.9
4.5
4.99
5
226
5.2
162
5.3
FPWM Mode Enable
The IC automatically defaults to SKIP mode operation at no load and light load conditions. Transition from skip mode
to PWM occurs when load current increases past a certain threshold. Another way to enable PWM operation is by
connecting the FPWM pin to logic HIGH level. This forces PWM mode (FPWM) regardless of load current at the output.
FPWM mode benefits applications where the lowest output ripple is required, whereas skip mode helps maximize the
buck-boost regulator’s efficiency at light loads.
Power-OK (POK) Indicator
The device features an open-drain POK output to monitor the output voltage. The POK pin requires an external pullup resistor and goes high (high-impedance) after the output increases above 92.5% (typ) of the target output voltage
(VOUT_TARGET). The POK pin goes low when the regulator output drops below 90% (typ) of VOUT_TARGET.
Protection Features
Undervoltage Lockout (UVLO)
The device supports a UVLO feature that prevents operation in abnormal input voltage conditions when VIN falls below
the VIN_UVLO_F threshold. Regardless of the EN pin status, the device disables until the input voltage VIN rises above
the VIN_UVLO_R threshold.
Soft-Start
The IC is equipped with a soft-start feature to limit large input-current draw from the system supply during device start-up.
During the soft-start time, the IC lowers the switching current-limit level from normal level and operates in FPWM mode.
See Table 1 for the ILIM levels of each part number.
www.maximintegrated.com
Maxim Integrated | 17
MAX77827
5.5V Input, 1.8A/3.1A Switch Buck-Boost
Converter with 6μA IQ
Output Active Discharge
The buck-boost provides an internal 100Ω switch for output active discharge function. The internal switch provides a path
to discharge the energy stored in the output capacitor to PGND whenever the regulator is disabled. While the regulator
remains enabled, the internal switch is disconnected from the output.
Overcurrent Protection (OCP)
The device features a robust switching current-limit scheme that protects the device and the inductor during overload and
fast transient conditions. The current-sense circuit takes current information from the high-side MOSFETs to determine
the peak-switching current (RDS(ON) x IL).
The IC provides two different cycle-by-cycle current limit levels (1.8A (typ) and 3.1A (typ)) for the high-side MOSFET. If
the switching current (ILIM) hits current limit for about 3ms, the IC shuts off the output for about 12ms, retries, and repeats
this cycle until the over-current condition is removed from the system.
SHORT
CIRCUIT
VOUT
3ms
3ms
ILIM
IL
12ms
Figure 3. Short-Circuit Waveform
Thermal Shutdown
The device has an internal thermal-protection circuit which monitors die temperature. The buck-boost disables if the
die temperature exceeds TSHDN (+165°C typ). The buck-boost enables again after the die temperature cools by
approximately +20°C.
www.maximintegrated.com
Maxim Integrated | 18
MAX77827
5.5V Input, 1.8A/3.1A Switch Buck-Boost
Converter with 6μA IQ
Applications Information
Inductor Selection
Buck-boost is optimized for a 1µH inductance. The lower the inductor DCR, the higher the buck-boost efficiency. Users
need to trade off inductor size with DCR value and choose a suitable inductor for the buck-boost.
The saturation current of the inductor should be higher than the maximum switching current limit to avoid inductor
saturation during operation. See the Electrical Characteristics table specifications for the maximum ILIM of each IC option.
Table 3 lists recommended inductors for the IC. Always choose the inductor carefully by consulting the manufacturer’s
latest released data sheet.
Table 3. Inductor Recommendations
NOMINAL
INDUCTANCE
(µH)
TYPICAL DC
RESISTANCE
(mΩ)
CURRENT
RATING (A)
-30 (ΔL/L)
CURRENT
RATING
(A)
ΔT = 40°C
RISE
DIMENSIONS
LxWxH
(mm)
DFE18SBN1R0ME0
1.0
120
3.1
2.4
1.6 x 0.8 x 0.8
B, D
CIGT201610EH1R0MNE
1.0
38
4.5
4.3
2.0 x 1.6 x 1.0
A, B, C, D
TaiyoYuden
MEKK2016H1R0M
1.0
41
4.5
3.7
2.0 x 1.6 x 1.0
A, B, C, D
MFGR.
Murata
Samsung
SERIES
OPTIONS
Cyntec
HTEH20120H-1R0MSR
1.0
45
3.8
3.5
2.0 x 1.2 x 0.8
A, B, C, D
Samsung
CIGT252010EH1R0MNE
1.0
26
5.0
4.3
2.5 x 2.0 x 1.0
A, B, C, D
Sumida
CDMT40D20HF-1R0NC
1.0
26
8.7
9.6
4.3 x 4.3 x 2.1
A, B, C, D
Coilcraft
XAL4020-102MEB
1.0
13
8.7
9.6
4.0 x 4.0 x 2.1
A, B, C, D
Input Capacitor Selection
The input capacitor, CIN, reduces the current peaks drawn from the battery or input power source and reduces switching
noise in the device. The impedance of CIN at the switching frequency should be kept very low. Ceramic capacitors with
X5R or X7R dielectrics are highly recommended due to their small size, low ESR, and small temperature coefficients.
For most applications, a 10V 10µF capacitor is sufficient.
Output Capacitor Selection
The output capacitor, COUT, is required to keep the output-voltage ripple small and to ensure regulation loop stability.
COUT must have low impedance at the switching frequency. Ceramic capacitors with X5R or X7R dielectric are highly
recommended due to their small size, low ESR, and small temperature coefficients. For stable operation, the buck-boost
requires 8µF of minimum effective output capacitance. Considering DC bias characteristic of ceramic capacitors, a 10V
22µF capacitor is recommended for most applications.
www.maximintegrated.com
Maxim Integrated | 19
MAX77827
5.5V Input, 1.8A/3.1A Switch Buck-Boost
Converter with 6μA IQ
PCB Layout Guidelines
Careful circuit board layout is critical to achieve low switching power losses and clean, stable operation. Figure 5 shows
an example PCB layout for the MAX77827 FC2QFN package. For the WLP package, a high density interconnect (HDI)
PCB is required. Figure 4 shows an example HDI PCB layout for the MAX77827 WLP package.
When designing the PCB, follow these guidelines:
1. Place the input capacitors CIN and output capacitors COUT immediately next to the IN pin and OUT pin, respectively,
of the IC. Since the IC operates at a high switching frequency, this placement is critical for minimizing parasitic
inductance within the input and output current loops, which can cause high voltage spikes and can damage the
internal switching MOSFETs.
2. Place the inductor next to the LX bumps/pins (as close as possible) and make the traces between the LX bumps/pins
and the inductor short and wide to minimize PCB trace impedance. Excessive PCB impedance reduces converter
efficiency. When routing LX traces on a separate layer (as in the examples), make sure to include enough vias to
minimize trace impedance. Routing LX traces on multiple layers is recommended to further reduce trace impedance.
Furthermore, do not allow LX traces to take up an excessive amount of area. The voltage on this node switches very
quickly and additional area creates more radiated emissions.
3. Prioritize the low-impedance ground plane of the PCB directly underneath the IC, COUT, CIN, and the inductor.
Cutting this ground plane risks interrupting the switching current loops.
4. AGND must carefully connect to PGND on the PCBs low-impedance ground plane. Connect AGND to the lowimpedance ground plane on the PCB (the same net as PGND) away from any critical loops.
5. The IC requires a supply input (BIAS) which is often the same net as IN. Carefully bypass BIAS to PGND with a
dedicated capacitor (CBIAS) as close as possible to the IC. Route a dedicated trace between CBIAS and the BIAS
bump/pin. Avoid connecting BIAS directly to the nearest IN bumps/pins without dedicated bypassing.
6. Connect the OUTS bump/pin to the regulating point with a dedicated trace away from noisy nets such as LX1 and
LX2.
7. Keep the power traces and load connections short and wide. This is essential for high converter efficiency.
8. Do not neglect ceramic capacitor DC voltage derating. Choose capacitor values and case sizes carefully. See the
Output Capacitor Selection section and refer to Tutorial 5527 for more information.
CBIAS
0402
AGND
RSEL
0402
K
PO
EN
LEGEND
FPWM
+
IN
COUT
0603
CIN
0603
OUT
0805 (2012)
0603
0402
PGND
LX1
L
2012
LX2
NOTE: PLACE CIN AND COUT CLOSE TO THE IC TO MINIMIZE
PARASITIC INDUCTANCE WITHIN THE LOOP
HDI µVIA
6 mil hole, 12 mil pad
COMPONENT SIZES LISTED IN
IMPERIAL (METRIC)
Figure 4. PCB Layout Example (WLP—B and D Options)
www.maximintegrated.com
Maxim Integrated | 20
5.5V Input, 1.8A/3.1A Switch Buck-Boost
Converter with 6μA IQ
POK
EN
AGND
FPWM
MAX77827
RSEL
0402
LEGEND
CBIAS
0402
+
OUT
0805 (2012)
IN
CIN
0603
COUT
0603
0603
0402
NON-HDI VIA
8 mil hole, 18 mil pad
PGND
COMPONENT SIZES LISTED IN
IMPERIAL (METRIC)
L
2012
LX1
LX2
NOTE: PLACE CIN AND COUT CLOSE TO THE IC TO MINIMIZE
PARASITIC INDUCTANCE WITHIN THE LOOP
Figure 5. PCB Layout Example (FC2QFN—B and D Options)
Typical Application Circuits
Typical Application Circuit
L
1μH
LX2
LX1
1.8V TO 5.5V
DC SOURCE
CIN
10μF
ENABLE
OUT
IN
MAX77827
COUT
22μF
OUTS
FPWM ENABLE
FPWM
EN
POWER-OK
POK
CBIAS
1μF
BIAS
VOUT
2.3V TO 5.3V
SEL
AGND
PGND
RSEL*
*CHOOSE RSEL VALUE BASED ON VOUT, SEE TABLE 2
www.maximintegrated.com
Maxim Integrated | 21
MAX77827
5.5V Input, 1.8A/3.1A Switch Buck-Boost
Converter with 6μA IQ
Ordering Information
PART NUMBER
TYP ILIM (A)
UVLO RISING MAX (V)
PIN-PACKAGE
MAX77827AEWC+T
3.1
1.8
12 WLP
MAX77827BEWC+T
1.8
2.6
12 WLP
MAX77827CEWC+T
3.1
2.6
12 WLP
MAX77827DEWC+T
1.8
1.8
12 WLP
MAX77827AEFD+T
3.1
1.8
14 FC2QFN
MAX77827BEFD+T
1.8
2.6
14 FC2QFN
MAX77827CEFD+T
3.1
2.6
14 FC2QFN
MAX77827DEFD+T
1.8
1.8
14 FC2QFN
+Denotes a lead(Pb)-free/RoHS-compliant package.
T = Tape and reel.
www.maximintegrated.com
Maxim Integrated | 22
MAX77827
5.5V Input, 1.8A/3.1A Switch Buck-Boost
Converter with 6μA IQ
Revision History
REVISION
NUMBER
REVISION
DATE
PAGES
CHANGED
0
4/19
Initial release
—
1
5/19
Updated Ordering Information table
22
2
6/19
Updated Ordering Information table
22
3
10/19
Updated General Description, Applications, Benefits and Features, and Package
Information sections, replaced all Typical Operating Characteristics and FC2QFN
Pin Configuration, updated Pin Description table, Table 1, Figure 2, and Table 3,
replaced PCB Layout Guidelines section, updated Ordering Information table
1, 6, 9–13, 15,
17, 20–22
4
3/20
Updated Electrical Characteristics table, Start Up section, Table 1, Table 3, and
Ordering Information table
7, 8, 15, 20, 23
5
8/21
Updated Table 2
DESCRIPTION
16, 17
For pricing, delivery, and ordering information, please visit Maxim Integrated’s online storefront at https://www.maximintegrated.com/en/storefront/storefront.html.
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.
© 2021 Maxim Integrated Products, Inc.
工商网监
湘ICP备2023018690号
