MAX77827BEFD+T [MAXIM]
5.5V Input, 1.8A/3.1A Switch Buck-Boost Converter with 6μA IQ;
| 型号： | MAX77827BEFD+T |
| 厂家： | 
MAXIM INTEGRATED PRODUCTS |
| 描述： | 5.5V Input, 1.8A/3.1A Switch Buck-Boost Converter with 6μA IQ |
| 文件： | 总23页 (文件大小：998K) |
| 中文： | 中文翻译 | 下载： | 下载PDF数据表文档文件 |
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MAX77827
5.5V Input, 1.8A/3.1A Switch Buck-Boost
Converter with 6μA I
Q
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 volt-
age range of 2.3V to 5.3V. The IC provides two different
switching current levels (1.8A and 3.1A) to optimize ex-
ternal component sizing based on given load current re-
quirements. With the 1.8A switching current-limit option,
the IC can support up to 1.0A load current in buck mode
● 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 I
Buck Mode)
Option,
LIM
● 900mA Maximum Output Current (1.8A I
Option,
LIM
Boost Mode 3.0V , 3.3V
)
IN
OUT
● 96% Peak Efficiency (3.3V , 3.3V
)
OUT
IN
● SKIP Mode for Higher Light-Load Efficiency
and 900mA in boost mode (V = 3.0V, V
= 3.3V).
● 6μA Ultra-Low Typical Quiescent Current (At T =
IN
OUT
J
+25°C)
The peak efficiency of 96% makes the IC one of the best
solutions as a DC/DC converter to supply a rail for battery-
powered portable applications.
● 2.5MHz Nominal Switching Frequency
● Enable Pin
● GPIO Pins for System Design Convenience
• FPWM (Forced PWM) Mode Selection Pin
• POK Indicator Pin
The IC features an adjustable output voltage, which can
be programmed from 2.3V to 5.3V through a single resis-
tor. 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 flex-
ibility that allow the IC to cover a wide range of applica-
tions 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
2
14.52mm SOLUTION SIZE
1.8V TO 5.5V
DC SOURCE
LX1
LX2
IN
OUT
V
OUT
C
22μF
C
10μF
OUT
IN
2.3V TO 5.3V
MAX77827
OUTS
FPWM
POK
FPWM ENABLE
POWER-OK
ENABLE
EN
L
2012
BIAS
SEL
C
BIAS
4.00mm
1μF
*
AGND
PGND
R
SEL
*CHOOSE R
VALUE BASED ON VOUT, SEE TABLE 2
SEL
19-100546; Rev 5; 8/21
MAX77827
5.5V Input, 1.8A/3.1A Switch Buck-Boost
Converter with 6μA I
Q
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
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Maxim Integrated | 2
MAX77827
5.5V Input, 1.8A/3.1A Switch Buck-Boost
Converter with 6μA I
Q
TABLE OF CONTENTS (CONTINUED)
Revision History . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 23
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Maxim Integrated | 3
MAX77827
5.5V Input, 1.8A/3.1A Switch Buck-Boost
Converter with 6μA I
Q
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
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Maxim Integrated | 4
MAX77827
5.5V Input, 1.8A/3.1A Switch Buck-Boost
Converter with 6μA I
Q
LIST OF TABLES
Table 1. I
Levels. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 14
LIM
Table 2. R
Selection Table . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 16
SEL
Table 3. Inductor Recommendations . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 19
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Maxim Integrated | 5
MAX77827
5.5V Input, 1.8A/3.1A Switch Buck-Boost
Converter with 6μA I
Q
Absolute Maximum Ratings
IN, OUT, BIAS to PGND........................................... -0.3V to +6V
Maximum Junction Temperature ......................................+150°C
Storage Temperature Range ..............................-65°C to +150°C
Soldering Temperature (reflow) ........................................+260°C
Continuous Power Dissipation
PGND to AGND..................................................... -0.3V to +0.3V
EN, SEL, FPWM, POK to AGND................-0.3V to V
FB to AGND................................................ -0.3V to V
+ 0.3V
+ 0.3V
BIAS
OUT
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
WLP Package (T = +70°C, derate 13.73mW/°C above
+70°C)......................................................................1098.4mW
A
FC2QFN Package (T = +70°C, derate 15.77mW/°C above
A
+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
Thermal Resistance, Four-Layer Board:
Refer to Application Note 1891
Junction to Ambient (θ
)
72.82 C°/W
N/A
JA
Junction to Case (θ
)
JC
14 FC2QFN
Package Code
Outline Number
F142A2F+1
21-100382
90-100127
Land Pattern Number
Thermal Resistance, Four-Layer Board:
Junction to Ambient (θ
)
63.4°C/W
N/A
JA
Junction to Case (θ
)
JC
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 I
Q
Electrical Characteristics
(V = 3.8V, V
IN
= 3.3V, typicals are at T ≈ T = +25°C. Limits are 100% production tested at T = +25°C. Limits over the operating
OUT
A J J
temperature range (T = -40°C to +125°C) are guaranteed by design and characterization, unless otherwise noted.)
J
PARAMETER
GENERAL
SYMBOL
CONDITIONS
MIN
TYP
MAX
UNITS
For A and D options
For B and C options
EN = Low, T = +25°C
1.8
2.6
5.5
5.5
2
Input Voltage Range
V
V
IN
0.1
3
Shutdown Supply
Current
J
I
µA
SHDN
EN = Low, T = -40°C to +125°C (Note 2)
J
8
I
SKIP mode, no switching
6
14
6
µA
Q_SKIP
Input Supply Current
I
FPWM mode, no load, no switching
2
mA
Q_PWM
Active Discharge
Resistance
R
100
165
Ω
DISCHG
Thermal Shutdown
H-BRIDGE
T
Rising, +20°C hysteresis
°C
SHDN
Output Voltage Range
V
External resistor programmable
2.3
-1
5.3
+1
V
OUT
PWM mode, T = +25°C
J
V
Output Voltage
Accuracy
OUT_ACC1
OUT_ACC2
PWM mode, T = -40°C to +125°C
-2
+2
%
J
V
SKIP mode, no load, T = +25°C
-1
+4.5
J
V
V
= 1.8V to 5.5V (for A and D options)
= 2.6V to 5.5V (for B and C options)
0.4
0.4
IN
Line Regulation
Load Regulation
%/V
%/A
IN
Note 1
0.25
I
= 0.5A, V changes from 3.4V to
OUT
IN
Line Transient
Response
V
V
/V
2.9V in 25µs (20mV/µs), L = 1µH,
C
50
mV
mV
OS1 US1
= 8µF (Note 1)
OUT_NOM
I
changes from 10mA to 0.5A in
OUT
Load Transient
Response
/V
15µs, L = 1µH, C
1)
= 8µF (Note
250
OS2 US2
OUT_NOM
T = -40°C to +125°C, for A and C
J
options
2.5
1.3
10
3.1
1.8
3.7
2.3
LX1/2 Current Limit
I
A
LIM_LX
T = -40°C to +125°C, for B and D
J
options
High-Side PMOS On
Resistance
R
I
= 100mA per switch
= 100mA per switch
130
110
mΩ
mΩ
DSON_P
LX
LX
Low-Side NMOS On
Resistance
R
I
15
DSON_N
PWM mode, T = +25°C
2.25
2.2
2.5
2.5
2.75
2.8
J
Switching Frequency
f
MHz
SW
PWM mode, T = -40°C to +125°C
J
From EN asserting to SEL detection
(Note 2)
Turn-On Delay Time
SEL Detection Time
t
100
600
µs
µs
ON_DLY
After turn-on delay to LX switching (Note
2)
t
SEL
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Maxim Integrated | 7
MAX77827
5.5V Input, 1.8A/3.1A Switch Buck-Boost
Converter with 6μA I
Q
Electrical Characteristics (continued)
(V = 3.8V, V
IN
= 3.3V, typicals are at T ≈ T = +25°C. Limits are 100% production tested at T = +25°C. Limits over the operating
OUT
A J J
temperature range (T = -40°C to +125°C) are guaranteed by design and characterization, unless otherwise noted.)
J
PARAMETER
SYMBOL
CONDITIONS
= 10mA (Note
MIN
TYP
MAX
UNITS
I
OUT
1), for B and D
options
1500
After SEL detection
to soft-start timer
finish
Soft-Start Time
t
µs
SS
I
= 10mA (Note
OUT
1), for A and C
options
200
Minimum Effective
Output Capacitance
C
V
0A < I
< 1A
OUT
8
µF
µA
EFF_MIN
LX1, LX2 Leakage
Current
V
LX1/2
= 0V or 5.5V, V
= 5.5V, V
=
IN
OUT
I
0.1
2
LK_85
5.5V, T = +85°C
J
SYS rising, options B and C
SYS rising, options A and D
2.4
1.70
1.9
2.5
2.6
1.80
2.2
UVLO_R
1.75
2.05
1.68
SYS Undervoltage-
Lockout Threshold
V
SYS falling, options B and C
SYS falling, options A and D
V
UVLO_F
1.62
1.74
ENABLE INPUT (EN)
EN Logic-Low Threshold
V
0.4
V
V
EN_L
EN Logic-High
Threshold
V
EN_H
1.3
FPWM INPUT
FPWM Logic-Low
Threshold
V
0.4
V
V
IL
FPWM Logic-High
Threshold
V
IH
1.3
FPWM Internal
Pulldown Resistance
R
PD
Pulldown resistor to GND
400
800
1600
kΩ
POK OUTPUT
POK Output Low
Voltage
V
I
= 1mA
0.4
+1
V
POK_L
SINK
POK Output High
Leakage
I
T = +25°C
-1
µA
POK_25C
J
V
of V
rising, expressed as a percentage
OUT
I
92.5
90
POK_R
OUT
POK Threshold
%
V
OUT
falling, expressed as a percentage
I
POK_F
of V
OUT
Note 1: Guaranteed by ATE characterization. Not directly tested in production.
Note 2: Guaranteed by design. Production tested through scan.
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Maxim Integrated | 8
MAX77827
5.5V Input, 1.8A/3.1A Switch Buck-Boost
Converter with 6μA I
Q
Typical Operating Characteristics
(V = 3.8V, V
= 3.3V, L = 1μH (Coilcraft XAL4020-102ME), Skip Mode, I
= 1.8A, T = +25°C, unless otherwise noted.)
LIM_LX A
IN
OUT
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Maxim Integrated | 9
MAX77827
5.5V Input, 1.8A/3.1A Switch Buck-Boost
Converter with 6μA I
Q
Typical Operating Characteristics (continued)
(V = 3.8V, V
= 3.3V, L = 1μH (Coilcraft XAL4020-102ME), Skip Mode, I
= 1.8A, T = +25°C, unless otherwise noted.)
LIM_LX A
IN
OUT
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Maxim Integrated | 10
MAX77827
5.5V Input, 1.8A/3.1A Switch Buck-Boost
Converter with 6μA I
Q
Typical Operating Characteristics (continued)
(V = 3.8V, V
= 3.3V, L = 1μH (Coilcraft XAL4020-102ME), Skip Mode, I
= 1.8A, T = +25°C, unless otherwise noted.)
LIM_LX A
IN
OUT
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Maxim Integrated | 11
MAX77827
5.5V Input, 1.8A/3.1A Switch Buck-Boost
Converter with 6μA I
Q
Pin Configurations
12 WLP
TOP VIEW
(BUMP SIDE DOWN)
MAX77827
1
2
3
4
+
A
B
C
LX1
PGND
LX2
IN
BIAS
AGND
FPWM
OUT
POK
SEL
EN
OUTS
12 WLP
(1.61mm x 2.01mm, 0.4mm PITCH)
14 FC2QFN
TOP VIEW
+
14
13
11
12
10 LX2
SEL
1
2
3
9
8
POK
EN
PGND
LX1
MAX77827
7
5
6
4
14 FC2QFN
(2.5mm x 2.5mm x 0.55mm PITCH)
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Maxim Integrated | 12
MAX77827
5.5V Input, 1.8A/3.1A Switch Buck-Boost
Converter with 6μA I
Q
Pin Description
PIN
NAME
FUNCTION
TYPE
12 WLP
A1
14 FC2QFN
8
6, 7
5
LX1
IN
Switching Node 1
Power
A2
Input. Bypass to PGND with a 10V 10μF capacitor.
Internal Bias. Bypass to PGND with a 10V 1μF capacitor.
Analog Ground
Power
Analog
Ground
Ground
A3
BIAS
AGND
PGND
FPWM
POK
SEL
A4
4
B1
9
Power Ground
B2
14
2
FPWM Mode Selection (active-high)
Power-OK Open-Drain Output (active-high)
Select the output voltage with resistor (see Table 2).
Switching Node 2
Digital Input
Digital Output
Analog
B3
B4
1
C1
10
11, 12
13
3
LX2
Power
C2
OUT
OUTS
EN
Output. Bypass to PGND with a 10V 22μF capacitor.
Output Sense
Power
C3
Analog
C4
Enable Pin
Digital Input
Functional Diagrams
Function Diagram
LX1
LX2
IN
OUT
CS1
CS2
CS2
UVLO
ILIM_PEAK
OCP
BIAS
PGND
OUT
MAX77827
ACTIVE
DISCHARGE
LOGIC
CONTROL
EN
FPWM
OUTS
POK
SLOPE
COMPENSATION
POK
TSHDN
CS1/CS2
COMP
TARGET
OUTPUT
SELECTOR
EAMP
SOFT-
START
SEL
REF
AGND
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Maxim Integrated | 13
MAX77827
5.5V Input, 1.8A/3.1A Switch Buck-Boost
Converter with 6μA I
Q
Detailed Description
Start Up
When the EN pin is set to high, the IC turns on the internal bias circuitry which takes typically 100µs (t
) to settle.
ON_DLY
After the internal bias circuitry is settled, the controller senses the SEL pin resistance to set the reference voltage. The
R
reading takes about 600µs (typ). After the IC reads the R value, it begins the soft-start process. During the
SEL
SEL
soft-start process, the IC lowers the I
level from normal I
level and ramps the output voltage. This prevents the
LIM
LIM
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
V
OUT
T
T
T
SS
ON_DLY
SEL
ILIM
ILIM_SS
I
L
Figure 1. Start-Up Waveform
The buck-boost is in FPWM mode for the entire duration of T . Current limit during soft-start (I
) increases to I
SS
LIM_SS
LIM
LIM
after approximately half of T . See Table 1 for a list of parts with their respective soft-start and normal operation I
SS
levels.
Table 1. I
Levels
LIM
PART NUMBER
I
(A)
I
(A)
LIM
LIM_SS
MAX77827BEWC+T, MAX77827BEFD+T, MAX77827DEWC+T, MAX77827DEFD+T
MAX77827AEWC+T, MAX77827AEFD+T, MAX77827CEWC+T, MAX77827CEFD+T
1.15
1.8
3.1
1.8
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Maxim Integrated | 14
MAX77827
5.5V Input, 1.8A/3.1A Switch Buck-Boost
Converter with 6μA I
Q
Immediate Shutdown Conditions
The following events immediately shutdown the buck-boost:
● Thermal Protection (T > +165°C)
J
● V
< SYS UVLO Falling Threshold (V
)
UVLO_F
SYS
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: V /L.
IN
● Φ2 Switch period (Phase 2: HS1 = ON, HS2 = ON) ramps inductor current up or down depending on the differential
voltage across the inductor: (V – V
)/L.
IN
OUT
● Φ3 Switch period (Phase 3: LS1 = ON, HS2 = ON) ramps inductor current down at a rate proportional to the output
voltage divided by inductance: (-V /L).
OUT
Boost operation (V < V
) utilizes phase 1 and phase 2 within a single clock period. See the representation of inductor
IN
OUT
current waveform for boost mode operation in Figure 2.
Buck operation (V > V ) utilizes phase 2 and phase 3 within a single clock period. See the representation of inductor
IN
OUT
current waveform for buck mode operation in Figure 2.
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Maxim Integrated | 15
MAX77827
5.5V Input, 1.8A/3.1A Switch Buck-Boost
Converter with 6μA I
Q
BUCK-BOOST H-BRIDGE
BUCK OPERATION
TOPOLOGY
Ф2
Ф2
IN
OUT
Ф3
Ф3
TSW
TSW
Ф2
HS1
HS2
CHARGE/DISCHARGE L
CLK
CLK
CLK
BOOST OPERATION
L
Ф3
Ф1
CHARGE L
Ф1
Ф2
Ф1
Ф2
LS1
LS2
DISCHARGE L
TSW
TSW
CLK
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. R
Selection Table
SEL
R
SEL
(kΩ)
V
(V)
OUT
909
2.3
768
634
536
452
383
324
267
191
133
113
95.3
80.6
66.5
2.4
2.5
2.6
2.7
2.8
2.8
2.85
2.9
3
3
3.1
3.15
3.15
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Maxim Integrated | 16
MAX77827
5.5V Input, 1.8A/3.1A Switch Buck-Boost
Converter with 6μA I
Q
Table 2. R
Selection Table (continued)
SEL
R
SEL
(kΩ)
V
(V)
OUT
56.2
Open
3.2
3.3
3.3
3.4
Short to GND
47.5
40.2
34
3.45
3.5
3.6
3.7
3.75
3.8
3.9
4
28
23.7
20
16.9
14
11.8
10
4.1
4.2
4.4
4.5
5
8.45
7.15
5.9
4.99
226
5.2
5.3
162
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 pull-
up resistor and goes high (high-impedance) after the output increases above 92.5% (typ) of the target output voltage
(V
). The POK pin goes low when the regulator output drops below 90% (typ) of V
.
OUT_TARGET
OUT_TARGET
Protection Features
Undervoltage Lockout (UVLO)
The device supports a UVLO feature that prevents operation in abnormal input voltage conditions when V falls below
IN
the V
the V
threshold. Regardless of the EN pin status, the device disables until the input voltage V rises above
IN_UVLO_F
IN_UVLO_R
IN
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 I
levels of each part number.
LIM
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Maxim Integrated | 17
MAX77827
5.5V Input, 1.8A/3.1A Switch Buck-Boost
Converter with 6μA I
Q
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 (R
x I ).
DS(ON)
L
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 (I ) hits current limit for about 3ms, the IC shuts off the output for about 12ms, retries, and repeats
LIM
this cycle until the over-current condition is removed from the system.
SHORT
CIRCUIT
V
OUT
3ms
3ms
I
LIM
I
L
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 T
approximately +20°C.
(+165°C typ). The buck-boost enables again after the die temperature cools by
SHDN
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Maxim Integrated | 18
MAX77827
5.5V Input, 1.8A/3.1A Switch Buck-Boost
Converter with 6μA I
Q
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 I
of each IC option.
LIM
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
CURRENT
NOMINAL
INDUCTANCE RESISTANCE
TYPICAL DC
CURRENT
RATING (A)
-30 (ΔL/L)
RATING
(A)
ΔT = 40°C
RISE
DIMENSIONS
L x W x H
(mm)
MFGR.
SERIES
OPTIONS
(µH)
(mΩ)
Murata
DFE18SBN1R0ME0
1.0
1.0
120
38
3.1
4.5
2.4
4.3
1.6 x 0.8 x 0.8
B, D
Samsung CIGT201610EH1R0MNE
2.0 x 1.6 x 1.0 A, B, C, D
Taiyo-
MEKK2016H1R0M
Yuden
1.0
41
4.5
3.7
2.0 x 1.6 x 1.0 A, B, C, D
Cyntec
HTEH20120H-1R0MSR
1.0
1.0
1.0
1.0
45
26
26
13
3.8
5.0
8.7
8.7
3.5
4.3
9.6
9.6
2.0 x 1.2 x 0.8 A, B, C, D
2.5 x 2.0 x 1.0 A, B, C, D
4.3 x 4.3 x 2.1 A, B, C, D
4.0 x 4.0 x 2.1 A, B, C, D
Samsung CIGT252010EH1R0MNE
Sumida CDMT40D20HF-1R0NC
Coilcraft XAL4020-102MEB
Input Capacitor Selection
The input capacitor, C , reduces the current peaks drawn from the battery or input power source and reduces switching
IN
noise in the device. The impedance of C at the switching frequency should be kept very low. Ceramic capacitors with
IN
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, C
, is required to keep the output-voltage ripple small and to ensure regulation loop stability.
OUT
C
must have low impedance at the switching frequency. Ceramic capacitors with X5R or X7R dielectric are highly
OUT
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.
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Maxim Integrated | 19
MAX77827
5.5V Input, 1.8A/3.1A Switch Buck-Boost
Converter with 6μA I
Q
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 C and output capacitors C
immediately next to the IN pin and OUT pin, respectively,
IN
OUT
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, C
Cutting this ground plane risks interrupting the switching current loops.
, C , and the inductor.
OUT
IN
4. AGND must carefully connect to PGND on the PCBs low-impedance ground plane. Connect AGND to the low-
impedance 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 (C
) as close as possible to the IC. Route a dedicated trace between C
and the BIAS
BIAS
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.
RSEL
0402
AGND
LEGEND
EN
FPWM
0805 (2012)
IN
OUT
0603
0402
HDI µVIA
L
2012
6 mil hole, 12 mil pad
LX1
LX2
COMPONENT SIZES LISTED IN
IMPERIAL (METRIC)
NOTE: PLACE C AND C
CLOSE TO THE IC TO MINIMIZE
OUT
IN
PARASITIC INDUCTANCE WITHIN THE LOOP
Figure 4. PCB Layout Example (WLP—B and D Options)
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Maxim Integrated | 20
MAX77827
5.5V Input, 1.8A/3.1A Switch Buck-Boost
Converter with 6μA I
Q
AGND
RSEL
0402
LEGEND
OUT
0805 (2012)
IN
0603
0402
NON-HDI VIA
8 mil hole, 18 mil pad
COMPONENT SIZES LISTED IN
IMPERIAL (METRIC)
L
2012
LX2
LX1
NOTE: PLACE C AND C
CLOSE TO THE IC TO MINIMIZE
OUT
IN
PARASITIC INDUCTANCE WITHIN THE LOOP
Figure 5. PCB Layout Example (FC2QFN—B and D Options)
Typical Application Circuits
Typical Application Circuit
L
1μH
LX1
LX2
1.8V TO 5.5V
DC SOURCE
IN
OUT
V
OUT
C
22μF
C
IN
OUT
2.3V TO 5.3V
10μF
MAX77827
OUTS
FPWM
POK
FPWM ENABLE
POWER-OK
ENABLE
EN
BIAS
SEL
C
BIAS
1μF
*
R
SEL
AGND
PGND
*CHOOSE R
VALUE BASED ON V , SEE TABLE 2
OUT
SEL
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Maxim Integrated | 21
MAX77827
5.5V Input, 1.8A/3.1A Switch Buck-Boost
Converter with 6μA I
Q
Ordering Information
PART NUMBER
TYP I
(A)
UVLO RISING MAX (V)
PIN-PACKAGE
12 WLP
LIM
MAX77827AEWC+T
MAX77827BEWC+T
MAX77827CEWC+T
MAX77827DEWC+T
MAX77827AEFD+T
MAX77827BEFD+T
MAX77827CEFD+T
MAX77827DEFD+T
3.1
1.8
2.6
2.6
1.8
1.8
2.6
2.6
1.8
1.8
3.1
1.8
3.1
1.8
3.1
1.8
12 WLP
12 WLP
12 WLP
14 FC2QFN
14 FC2QFN
14 FC2QFN
14 FC2QFN
+Denotes a lead(Pb)-free/RoHS-compliant package.
T = Tape and reel.
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Maxim Integrated | 22
MAX77827
5.5V Input, 1.8A/3.1A Switch Buck-Boost
Converter with 6μA I
Q
Revision History
REVISION REVISION
PAGES
CHANGED
DESCRIPTION
NUMBER
DATE
4/19
5/19
6/19
0
1
2
Initial release
—
22
22
Updated Ordering Information table
Updated Ordering Information table
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
3
10/19
Updated Electrical Characteristics table, Start Up section, Table 1, Table 3, and
Ordering Information table
4
5
3/20
8/21
7, 8, 15, 20, 23
16, 17
Updated Table 2
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.
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