Junction Temperature ......................................................+150°C
Storage Temperature Range ............................ -65°C to +160°C
Lead Temperature (soldering, 10s) ................................. +300°C
Soldering Temperature (reflow) .......................................+260°C
Absolute Maximum Ratings
V
IN
to PGND .........................................................-0.3V to +48V
EN/UVLO to SGND ...............................................-0.3V to +48V
LX to PGND................................................-0.3V to (V
IN
+ 0.3V)
BST to PGND ........................................................-0.3V to +53V
BST to LX .............................................................-0.3V to +6.5V
BST to V
CC
...........................................................-0.3V to +48V
CF,
RESET,
SS, MODE, SYNC,
RT to SGND .....................................................-0.3V to +6.5V
FB to SGND .........................................................-0.3V to +1.5V
V
CC
to SGND .......................................................-0.3V to +6.5V
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. Junction temperature greater than +125°C degrades operating lifetimes.
Package Thermal Characteristics
(Note 1)
TQFN
Junction-to-Ambient Thermal Resistance (θ
JA
) ..........30°C/W
Junction-to-Case Thermal Resistance (θ
JC
) .................2°C/W
Note 1:
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
IN
= V
EN/UVLO
= 24V, R
RT
= 40.2kΩ (500kHz), C
VCC
= 2.2μF, V
PGND
= V
SGND
= V
MODE
= V
SYNC
= 0V, LX = SS =
RESET
=
open, V
BST
to V
LX
= 5V, V
FB
= 1V, T
A
= -40°C to +125°C, unless otherwise noted. Typical values are at T
A
= +25°C. All voltages are
referenced to SGND, unless otherwise noted.) (Note 2)
PARAMETER
INPUT SUPPLY (V
IN
)
Input Voltage Range
Input Shutdown Current
V
IN
I
IN-SH
I
Q_PFM
Input Quiescent Current
I
Q-DCM
I
Q_PWM
ENABLE/UVLO (EN/UVLO)
EN/UVLO Threshold
EN/UVLO Input Leakage Current
LDO
V
CC
Output Voltage Range
V
CC
Current Limit
V
CC
Dropout
V
CC
UVLO
V
CC
I
VCC-MAX
V
CC-DO
V
CC_UVR
V
CC_UVF
6V < V
IN
< 42V, I
VCC
= 1mA
1mA ≤ I
VCC
≤ 25mA
V
CC
= 4.3V, V
IN
= 6V
V
IN
= 4.5V, I
VCC
= 20mA
V
CC
rising
V
CC
falling
4.75
26.5
4.2
4.05
3.65
4.2
3.8
4.3
3.9
5
54
5.25
100
V
mA
V
V
V
ENR
V
ENF
I
EN
V
EN/UVLO
rising
V
EN/UVLO
falling
V
EN/UVLO
= 0V, T
A
= +25°C
1.19
1.068
-50
1.215
1.09
0
1.26
1.131
+50
V
nA
V
EN/UVLO
= 0V (shutdown mode)
V
FB
= 1V, MODE = RT = open
V
FB
= 1V, MODE = open
DCM mode, V
LX
= 0.1V
Normal switching mode, f
SW
= 500kHz,
V
FB
= 0.8V
4.5
2.8
118
162
1.16
9.5
1.8
mA
42
4.5
µA
V
SYMBOL
CONDITIONS
MIN
TYP
MAX
UNITS
www.maximintegrated.com
Maxim Integrated
│
2
MAX17544
4.5V–42V, 3.5A, High-Efficiency,
Synchronous Step-Down DC-DC Converter
With Internal Compensation
Electrical Characteristics (continued)
(V
IN
= V
EN/UVLO
= 24V, R
RT
= 40.2kΩ (500kHz), C
VCC
= 2.2μF, V
PGND
= V
SGND
= V
MODE
= V
SYNC
= 0V, LX = SS =
RESET
=
open, V
BST
to V
LX
= 5V, V
FB
= 1V, T
A
= -40°C to +125°C, unless otherwise noted. Typical values are at T
A
= +25°C. All voltages are
referenced to SGND, unless otherwise noted.) (Note 2)
PARAMETER
POWER MOSFET AND BST DRIVER
High-Side nMOS On-Resistance
Low-Side nMOS On-Resistance
LX Leakage Current
SOFT-START (SS)
Charging Current
FEEDBACK (FB)
FB Regulation Voltage
FB Input Bias Current
MODE
V
M-DCM
MODE Threshold
V
M-PFM
V
M-PWM
CURRENT LIMIT
Peak Current-Limit Threshold
Runaway Current-Limit Threshold
Valley Current-Limit Threshold
PFM Current-Limit Threshold
RT AND SYNC
R
RT
= 210kΩ
R
RT
=
102kΩ
Switching Frequency
f
SW
R
RT
=
40.2kΩ
R
RT
=
8.06kΩ
R
RT
= open
SYNC Frequency Capture Range
SYNC Pulse Width
SYNC Threshold
FB Undervoltage Trip Level to
Cause Hiccup
V
IH
V
IL
V
FB-HICF
0.56
0.58
f
SW
set by R
RT
90
180
475
1950
460
1.1 x
f
SW
50
2.1
0.8
0.65
100
200
500
2200
500
110
220
525
2450
540
1.4 x
f
SW
kHz
ns
V
V
kHz
I
PEAK-LIMIT
I
RUNAWAY-LIMIT
I
SINK-LIMIT
I
PFM
MODE = open/V
CC
MODE = GND
MODE = open
0.6
4.4
4.9
-0.16
5.1
5.7
0
-1.8
0.75
0.9
5.85
6.7
+0.16
A
A
A
A
MODE = V
CC
(DCM mode)
MODE = open (PFM mode)
MODE = GND (PWM mode)
V
CC
- 1.6
V
CC
/ 2
1.4
V
V
FB_REG
I
FB
MODE = SGND or MODE = V
CC
MODE = OPEN
0 < V
FB
< 1V, T
A
= +25°C
0.89
0.89
-50
0.9
0.915
0.91
0.936
+50
V
nA
I
SS
V
SS
= 0.5V
4.7
5
5.3
µA
R
DS-ONH
R
DS-ONL
I
LX_LKG
I
LX
= 0.3A
I
LX
= 0.3A
V
LX
= V
IN
- 1V, V
LX
= V
PGND
+ 1V, T
A
= +25°C
-2
165
80
325
150
+2
mΩ
mΩ
µA
SYMBOL
CONDITIONS
MIN
TYP
MAX
UNITS
www.maximintegrated.com
Maxim Integrated
│
3
MAX17544
4.5V–42V, 3.5A, High-Efficiency,
Synchronous Step-Down DC-DC Converter
With Internal Compensation
Electrical Characteristics (continued)
(V
IN
= V
EN/UVLO
= 24V, R
RT
= 40.2kΩ (500kHz), C
VCC
= 2.2μF, V
PGND
= V
SGND
= V
MODE
= V
SYNC
= 0V, LX = SS =
RESET
=
open, V
BST
to V
LX
= 5V, V
FB
= 1V, T
A
= -40°C to +125°C, unless otherwise noted. Typical values are at T
A
= +25°C. All voltages are
referenced to SGND, unless otherwise noted.) (Note 2)
PARAMETER
Hiccup Timeout
Minimum On-Time
Minimum Off-Time
LX Dead Time
RESET
RESET
Output Level Low
RESET
Output Leakage Current
FB Threshold for
RESET
Assertion
FB Threshold for
RESET
Deassertion
RESET
Deassertion Delay After FB
Reaches 95% Regulation
THERMAL SHUTDOWN
Thermal-Shutdown Threshold
Thermal-Shutdown Hysteresis
Note 2:
All limits are 100% tested at +25ºC. Limits over temperature are guaranteed by design.
Note 3:
See the Overcurrent
Protection/Hiccup Mode
section for more details.
Temperature rising
165
10
°C
°C
V
FB-OKF
V
FB-OKR
I
RESET
= 10mA
T
A
= T
J
= +25°C, V
RESET
= 5.5V
V
FB
falling
V
FB
rising
-0.1
90.5
93.8
92
95
1024
t
ON-MIN
t
OFF-MIN
140
5
0.4
+0.1
94.6
97.8
SYMBOL
(Note 3)
CONDITIONS
MIN
TYP
32,768
135
160
MAX
UNITS
Cycles
ns
ns
ns
V
µA
%V
FB-
REG
%V
FB-
REG
Cycles
www.maximintegrated.com
Maxim Integrated
│
4
MAX17544
4.5V–42V, 3.5A, High-Efficiency,
Synchronous Step-Down DC-DC Converter
With Internal Compensation
Typical Operating Characteristics
(V
IN
= V
EN/UVLO
= 24V, V
PGND
= V
SGND
= 0V, C
VIN
= C
VCC
= 2.2µF, C
BST
= 0.1µF, C
SS
= 5600pF, RT = MODE = open, T
A
= -40°C to
+125°C, unless otherwise noted. Typical values are at T
A
= +25°C. All voltages are referenced to GND, unless otherwise noted.)
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