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MAX38886
2.5V to 5.0V, 0.5A/2.5A, Charge/Discharge
Regulator for Supercapacitor Backup
Applications
Benefits and Features
•
•
•
•
•
•
•
•
2.5V to 5V System Output Voltage
Up to 4.5V Capacitor Voltage Range
Up to 2.5A Peak Inductor Discharge Current
Programmable Voltage and Current Thresholds
±2% Threshold Accuracy
Up to 95% Efficiency, Charge or Discharge
2.5μA Ready Quiescent Current
Small Solution Size
• 3mm x 3mm x 0.75mm TDFN Package
General Description
The MAX38886 is a storage capacitor or capacitor bank
backup regulator designed to efficiently transfer power
between a storage element and a system supply rail in
reversible buck and boost operations using the same
inductor.
When the main supply is present and above the
minimum system supply voltage, the regulator operates
in buck mode and charges the storage element at up to
500mA peak inductor current. Once the storage element
is charged, the circuit draws only 2.5μA of current while
it maintains the supercapacitor or other storage element
in its ready state. When the main supply is removed, the
regulator operates in boost mode and prevents the
system from dropping below the minimum operating
voltage, discharging the storage element at up to 2.5A
peak inductor current.
The MAX38886 is externally programmable for minimum
and maximum voltage of the storage element, such as
supercapacitor, minimum system voltage, and maximum
charge and discharge currents. The internal DC-DC
converter requires only a 1μH inductor.
Ordering Information
appears at the end of data sheet.
Applications
•
•
•
Handheld Industrial Equipment
Portable Computers
Portable Devices with a Removable Battery
Simplified Block Diagram
CHARGE
L1
1µH
VSC
2.7V (MAX)
CAP
LX
SYS
R
STOP
2.49MΩ
C1
22µF
V
SYS
SYSTEM LOAD
3V (MIN)
DISCHARGE
+
10F
SUPER
CAP
C2
22µF
CAPS
R
CTOP
2.1MΩ
FBCH
MAX38886
MAIN
BATTERY
(REMOVABLE)
FBS
ENABLE
R
CBOT
499kΩ
EN
GND
ISET
R
ISET
20kΩ
R
SBOT
499kΩ
www.maximintegrated.com
19-100855; Rev 1; 8/20
MAX38886
2.5V to 5.0V, 0.5A/2.5A, Charge/Discharge
Regulator for Supercapacitor Backup Applications
Absolute Maximum Ratings
CAP, EN, SYS, LX to GND ................................... -0.3V to +6V
FBCH to GND ............................................ -0.3V to CAP +0.3V
FBS, ISET to GND ..................................... -0.3V to SYS +0.3V
PGND to GND .................................................... -0.3V to +0.3V
LX RMS Current ........................................................ +2.0A
RMS
Continuous Power Dissipation (T
A
= +70°C, TDFN, derate
24.4mW/°C above +70°C) ....................................... 1951.2mW
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.
Output Short-Circuit Duration ..................................Continuous
Operating Temperature Range........................-40ºC to +125ºC
Storage Temperature Range ...........................-65ºC to +150ºC
Maximum Junction Temperature ................................... +150ºC
Lead Temperature (Soldering,10 seconds) ................... +300ºC
Package Information
Package Code
Outline Number
Land Pattern Number
Thermal Resistance, Four-Layer Board:
Junction-to-Ambient (θ
JA
)
Junction-to-Case Thermal Resistance (θ
JC
)
41°C/W
8°C/W
T1433+2C
21-0137
90-0063
For
the
latest
package
outline
information
and
land
patterns
(footprints),
go
to
https://www.maximintegrated.com/en/design/packaging.html.
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.
Electrical Characteristics
(V
SYS
= 3.7V, V
CAP
= 2.7V, Typical values are at T
J
= -40ºC to +125ºC, unless otherwise specified.)
PARAMETER
SYS Voltage Range
CAP Voltage
Min CAP Voltage
SYS Shutdown Current
SYS Charging Supply
Current
SYS Backup Supply
Current
SYS Ready Supply
Current
CAP Shutdown Current
www.maximintegrated.com
SYMBOL
V
SYS
V
CAP
V
CAP
I
SYS_SD
I
SYS_CHG
I
SYS_BUP
CONDITIONS
MIN
2.5
TYP
MAX
5
4.5
UNITS
V
V
V
0.5
EN = 0V, T
A
= +25ºC
EN = 0V
V
FBS
= 0.6V, V
FBCH
= 0.485V
V
FBS
= V
FBCH
= 0.515V, T
A
= +25°C
V
FBS
= V
FBCH
= 0.515V
V
FBS
= 0.6V, V
FBCH
= 0.515V,
T
A
= +25°C
V
FBS
= 0.6V, V
FBCH
= 0.515V
EN = 0V, T
A
= +25ºC
0.01
0.1
1.5
35
35
2.5
2.5
0.01
1
5
65
1
µA
mA
µA
I
SYS_RDY
I
CAP_SD
µA
µA
Maxim Integrated | 2
MAX38886
2.5V to 5.0V, 0.5A/2.5A, Charge/Discharge
Regulator for Supercapacitor Backup Applications
SYMBOL
EN = 0V
CONDITIONS
MIN
TYP
0.1
1.7
-2%
25
-2%
225
1.8
0.5
60
0.5
600
660
20
2.0
2.5
0.5
400
500
100
-0.1
0.001
0.01
-0.1
0.001
0.01
2
50
80
-1
0.1
320
80
400
100
165
25
25
50
50
75
75
480
120
ns
ns
°C
mA
mA
100
160
1
0.1
0.1
µA
600
mA
925
100
3.0
A
1.9
+2%
95
2%
V
V
mV
V
mV
kΩ
MAX
UNITS
(V
SYS
= 3.7V, V
CAP
= 2.7V, Typical values are at T
J
= -40ºC to +125ºC, unless otherwise specified.)
PARAMETER
UVLO Threshold
FBS Backup Voltage
FBS Charging
Threshold
FBCH Threshold
EN Threshold
ISET Resistor Range
LX Peak Backup
Current Limit (Note 1)
V
UVLOF
V
FBS
V
TH_FBS_CHG
V
TH_FBCH
V
IL
V
IH
R
ISET
I
DCHG
V
VSYS
falling, 100mV typical hysteresis
FBS rising, when discharging stops
Above FBS backup voltage, when
charging begins, 30mV typical hysteresis
FBCH rising, when charging stops, 25mV
typical hysteresis
When LX stops switching, EN falling
EN rising
Guaranteed by LX peak current limits
Circuit of
Figure 1,
V
CAP
= 2V,
V
SYS
= 2.9V, R
ISET
= 20kΩ
Circuit of
Figure 1,
V
CAP
= 2V,
V
SYS
= 2.9V, R
ISET
= 100kΩ
Circuit of
Figure 1,
V
SYS
= 3.7V,
V
CAP
= 2V, R
ISET
= 20kΩ
Circuit of
Figure 1,
V
SYS
=3.7 V,
V
CAP
= 2V, R
ISET
= 100kΩ
V
FBS/FBCH
= 0.5V, T
A
= +25°C
V
FBS/FBCH
= 0.5V
0V < V
EN
< 5.5V, T
A
= +25°C
0V < V
EN
< 5.5V
Delivering maximum current from CAP
V
SYS
= 3V, LX switched to GND
V
SYS
= 3V, LX switched to SYS
V
EN
= 0V, V
SYS
= 5V, V
LX
= 0V/5V,
T
A
= +25°C
V
EN
= 0V, V
SYS
= 5V, V
LX
= 0V/5V
Backup mode, V
FBS
= 0.485V
Backup mode, V
FBS
= 0.485V
T
J
rising, 15°C typical hysteresis
Circuit of
Figure 1,
V
CAP
= 2V,
V
SYS
= 2.9V
Circuit of
Figure 1,
V
SYS
= 3.7V,
V
CAP
= 2V
LX Peak Charge
Current Limit (Note 1)
FBS/FBCH Input Bias
Current
EN Input Leakage
Current
LX Switching Frequency
LX Low-Side FET
Resistance
LX High-Side FET
Resistance
LX Leakage Current
Maximum On-Time
Minimum Off-Time
Overtemperature
Lockout Threshold
High-Side FET
Zero-Crossing (Note 1)
Low-Side FET
Zero-Crossing (Note 1)
I
CHG
I
FBS/FBCH
I
EN
f
SW
R
LOW
R
HIGH
I
LX_LKG
t
ON
t
OFF
T
OTLO
I
ZXP
I
ZXN
µA
MHz
mΩ
mΩ
µA
Note 1:
DC measurement, actual zero-crossing and peak current accuracy in circuit will be affected by the propagation delay time.
Note 2:
Limits over the specified operating temperature and supply voltage range are guaranteed by design and characterization,
and production tested at T
J
= +25ºC only.
www.maximintegrated.com
Maxim Integrated | 3
MAX38886
2.5V to 5.0V, 0.5A/2.5A, Charge/Discharge
Regulator for Supercapacitor Backup Applications
Typical Operating Characteristics
(MAX38886, V
SYS
= 3.6V, V
CAP
= 2.0V, C1 = 22µF, C2 = 22µF, T
A
= +25°C, unless otherwise noted.)
www.maximintegrated.com
Maxim Integrated | 4
MAX38886
2.5V to 5.0V, 0.5A/2.5A, Charge/Discharge
Regulator for Supercapacitor Backup Applications
www.maximintegrated.com
Maxim Integrated | 5
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