Datasheet
MAX8855/MAX8855A
Dual, 5A, 2MHz Step-Down Regulators
2 _______________________________________________________________________________________
ABSOLUTE MAXIMUM RATINGS
ELECTRICAL CHARACTERISTICS
(V
IN_
= V
VDD
= V
VDL
= 3.3V, V
FB_
= 0.5V, V
SS_
= V
REFIN
= 600mV, PGND_ = GND, R
FSYNC
= 10kΩ, L = 0.47μH, C
BST_
= 0.1μF,
C
SS_
= 0.022μF, PWRGD_ not connected; T
A
= -40°C to +85°C, typical values are at T
A
= +25°C, unless otherwise noted.) (Note 2)
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.
IN_, LX_, V
DD
, VDL, PWRGD_ to GND..................-0.3V to +4.5V
V
DD
, VDL to IN_.....................................................-0.3V to +4.5V
EN_, SS_, COMP_, FB_, REFIN, FSYNC to GND ......-0.3V to the
lower of (V
VDD
+ 0.3V) and (V
VDL
+ 0.3V)
Continuous LX_ Current (Note 1) ...................................5.5A
RMS
BST_ to LX_ ...........................................................-0.3V to +4.5V
PGND_ to GND......................................................-0.3V to +0.3V
Continuous Power Dissipation (T
A
= +70°C)
32-Pin TQFN (5mm x 5mm)
(derate 34.5mW/°C above +70°C)..........................2758.6mW
Operating Ambient Temperature Range .............-40°C to +85°C
Operating Junction Temperature Range...........-40°C to +125°C
Storage Temperature Range .............................-65°C to +150°C
Lead Temperature (soldering, 10s) .................................+300°C
Soldering Temperature (reflow) .......................................+260°C
PARAMETER CONDITIONS MIN TYP MAX UNITS
IN1, IN2, VDL, VDD
MAX8855 2.35 3.60
IN_, VDL, and V
DD
Voltage Range (Note 3)
MAX8855A 2.25 3.60
V
V
IN_
= 2.5V 1.9 3.5
IN_ Supply Current 1MHz switching, no load
V
IN_
= 3.3V 2.8 5
mA
V
VDD
= 2.5V 7.2
V
DD
+ VDL Supply Current 1MHz switching, V
DD
= VDL
V
VDD
= 3.3V 10 15
mA
T
A
= +25°C 11
Shutdown Supply Current
(I
IN1
+ I
IN2
+ I
VDD
+ I
VDL
)
V
IN_
= V
VDD
= V
VDL
= V
B S T _
-
V
L X _
= 3.6V , V
E N _
= 0V
T
A
= +85°C 0.3
μA
Rising
2.0 2.2
IN_, V
DD
Undervoltage Lockout Threshold
UVLO Monitors V
DD
, IN1, and IN2
Falling 1.8 1.9
V
IN_, V
DD
Undervoltage Lockout Deglitch 2 μs
BST1, BST2
T
A
= +25°C 2
Shutdown BST_ Current
V
IN _
= V
VD D
= V
VD L
= V
BS T_
=
3.6V, V
EN
_
= 0V, V
LX
_
= 0 or 3.6V
T
A
= +85°C 0.02
μA
COMP1, COMP2
COMP_ Clamp Voltage, High V
VDD
= V
IN_
= 2.25V to 3.6V, V
FB_
= 0.7V 1.80 2.00 2.25 V
COMP_ Slew Rate 1.40 V/μs
COMP_ Shutdown Resistance From COMP_ to GND, V
EN_
= 0V 7 25 Ω
Note 1: LX_ have internal clamp diodes to PGND_ and IN_. Applications that forward bias these diodes should take care not to
exceed the IC’s package power-dissipation limits.
Note 2: 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.maxim-ic.com/thermal-tutorial
.
PACKAGE THERMAL CHARACTERISTICS (Note 2)
TQFN
Junction-to-Ambient Thermal Resistance (θ
JA
) ...........29°C/W
Junction-to-Case Thermal Resistance (θ
JC
) ...............1.7°C/W