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 Thermal Characteristics
(Note 1)
TDFN
Junction-to-Ambient Thermal Resistance (θ
JA
) .......67.3°C/W
Junction-to-Case Thermal Resistance (θ
JC
) ............18.2°C/W
μMAX
Junction-to-Ambient Thermal Resistance (θ
JA
) .....113.1°C/W
Junction-to-Case Thermal Resistance (θ
JC
) ...............42°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
= 24V, V
GND
= 0V, V
OUT
= 3.3V, V
FB
= 0.85V, V
EN/UVLO
= 1.5V, RT/SYNC = 191kΩ, LX = SS = MODE =
RESET
= unconnected;
T
A
= T
J
= -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.) (Note 3)
PARAMETER
INPUT SUPPLY (IN)
Input Voltage Range
Input Shutdown Current
Input Supply Current
EXTERNAL BIAS (V
OUT
)
V
OUT
Switchover Threshold
ENABLE/UVLO (EN/UVLO)
V
ENR
EN/UVLO Threshold
EN/UVLO Leakage Current
POWER MOSFETs
High-Side pMOS On-Resistance
Low-Side nMOS On-Resistance
LX Leakage Current
R
DS-ONH
R
DS-ONL
I
LX-LKG
I
LX
= 0.1A (sourcing)
I
LX
= 0.1A (sinking)
V
EN
= 0V, T
A
= +25°C,
V
LX
= (V
GND
+ 1V) to (V
IN
- 1V)
3.2
1.6
-1
5.9
3.0
11.1
6
+1
Ω
Ω
µA
V
ENF
V
EN-TRUESD
I
EN
V
EN/UVLO
rising
V
EN/UVLO
falling
V
EN/UVLO
falling, true shutdown
V
EN/UVLO
= 1.3V, T
A
= +25°C
-100
1.2
1.1
1.25
1.15
0.7
+100
nA
1.3
1.2
V
2.96
3.05
3.12
V
V
IN
I
IN-SH
I
Q-PFM
I
Q-PWM
V
EN/UVLO
= 0V, T
A
= +25°C
V
MODE
= unconnected (Note 2)
Normal switching mode, V
IN
= 24V
180
4
0.67
1.2
18
485
60
2.25
32
650
µA
V
SYMBOL
CONDITIONS
MIN
TYP
MAX
UNITS
www.maximintegrated.com
Maxim Integrated
│
2
MAX17550
60V, 25mA, Ultra-Small, High-Efficiency
Synchronous Step-Down DC-DC Converter
with 22µA No-Load Supply Current
Electrical Characteristics (continued)
(V
IN
= 24V, V
GND
= 0V, V
OUT
= 3.3V, V
FB
= 0.85V, V
EN/UVLO
= 1.5V, RT/SYNC = 191kΩ, LX = SS = MODE =
RESET
= unconnected;
T
A
= T
J
= -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.) (Note 3)
PARAMETER
SOFT-START (SS)
Soft-Start Time
SS Charging Current
FEEDBACK (FB)
FB Regulation Voltage
FB Input Leakage Current
CURRENT LIMIT
Peak Current-Limit Threshold
Negative Current-Limit Threshold
PFM Current Level
CURRENT LIMIT
R
RT
= 422kΩ
R
RT
= 191kΩ
Switching Frequency
f
SW
R
RT
= 130kΩ
R
RT
= 69.8kΩ
R
RT
= 45.3kΩ
R
RT
= 19.1kΩ
Switching-Frequency Adjustable
Range
SYNC Input Frequency
SYNC Pulse Minimum Off-Time
SYNC Rising Threshold
Hysteresis
Number of SYNC Pulses to
Enable Synchronization
TIMING
Minimum On-Time
t
ON-MIN
D
MAX
f
SW
≤ 600kHz,
V
FB
= 0.98 x V
FB-REG
f
SW
> 600kHz,
V
FB
= 0.98 x V
FB-REG
46
90
87
82
94
92
51
ms
128
98
%
ns
V
SYNC-H
V
SYNC-HYS
See the
Switching Frequency
(RT/SYNC)
section for details
90
205
295
540
813
1.86
100
1.1 x f
SW
40
1
0.115
1.22
0.18
1
1.44
0.265
100
220
319
592
900
2.08
111
235
340
638
973
2.3
2200
2200
MHz
kHz
kHz
ns
V
Cycles
kHz
I
PEAK-LIMIT
I
SINK-LIMIT
I
PFM
V
MODE
= GND
V
MODE
= unconnected
V
MODE
= unconnected
17
66
24
72
32
0.01
23
29
78
40
mA
mA
mA
V
FB-REG
I
FB
MODE = GND
MODE = unconnected
V
FB
= 1V, T
A
= 25°C
0.786
0.786
-100
0.8
0.812
0.814
0.826
+100
V
nA
t
SS
I
SS
SS = unconnected
V
SS
= 0.4V
4.4
4.7
5.1
5
5.8
5.3
ms
µA
SYMBOL
CONDITIONS
MIN
TYP
MAX
UNITS
Maximum Duty Cycle
Hiccup Timeout
www.maximintegrated.com
Maxim Integrated
│
3
MAX17550
60V, 25mA, Ultra-Small, High-Efficiency
Synchronous Step-Down DC-DC Converter
with 22µA No-Load Supply Current
Electrical Characteristics (continued)
(V
IN
= 24V, V
GND
= 0V, V
OUT
= 3.3V, V
FB
= 0.85V, V
EN/UVLO
= 1.5V, RT/SYNC = 191kΩ, LX = SS = MODE =
RESET
= unconnected;
T
A
= T
J
= -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.) (Note 3)
RESET
PARAMETER
SYMBOL
V
FB-OKR
V
FB-OKF
V
FB
rising
V
FB
falling
CONDITIONS
MIN
93
90
TYP
95
92
2.1
I
RESET
= 1mA
V
FB
= 1.01 x V
FB-REG
, T
A
= +25°C
0.23
1
MAX
97
94
UNITS
%
%
ms
V
µA
FB Threshold for
RESET
Rising
FB Threshold for
RESET
Falling
RESET
Delay after FB Reaches
95% Regulation
RESET
Output Level Low
RESET
Output Leakage Current
Output Leakage Current
MODE
MODE PFM Threshold
MODE Hysteresis
MODE Internal Pullup Resistor
THERMAL SHUTDOWN
Thermal-Shutdown Threshold
Thermal-Shutdown Hysteresis
V
MODE-PFM
V
MODE-HYS
V
MODE
= unconnected
V
MODE
= GND
V
MODE-PFM
V
MODE-HYS
Temperature rising
1
1.22
0.19
123
1390
160
20
1.44
V
V
kΩ
°C
°C
Note 2:
Actual I
Q-PFM
in the application circuit is higher due to additional current in the output voltage feedback resistor divider. For
example, I
Q-PFM
(MODE = unconnected) = 26µA for
Figure 6,
22µA for
Figure 7,
and 78µA for
Figure 11.
Note 3:
Limits are 100% tested at T
A
= +25°C. Limits over the operating temperature range and relevant supply voltage range are
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