Junction Temperature ......................................................+150°C
Storage Temperature Range ............................ -65°C to +160°C
Lead Temperature (soldering, 10s) ................................. +300°C
Soldering Temperature (reflow) .......................................+260°C
Note 1:
Junction temperature greater than +125°C degrades operating lifetimes.
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
PACKAGE TYPE: 24-PIN TQFN
Package Code
Outline Number
Land Pattern Number
THERMAL RESISTANCE, FOUR-LAYER BOARD
Junction to Ambient (θ
JA
)
Junction to Case (θ
JC
)
35°C/W
1.8°C/W
T2445+1C
21-0201
90-0083
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.
Electrical Characteristics
(V
IN_
= +24V, V
SGND_
= V
PGND_
= V
FSEL
= 0V, C
IN_
= 2.2μF, C
VCC_
= 1μF, V
EN/UVLO_
= 1.5V, C
SS_
= 0.01μF, FB_ = 0.98 x V
FB-REG
,
COMP_ = unconnected, LX_ = unconnected,
RESET_
= unconnected. 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
Input Switching Current
V
IN_
I
IN-SH
I
Q_PFM_
I
Q_PWM_
V
EN_
= 0V, shutdown mode
V
MODE_
> 2V
V
MODE_
< 0.8V,
V
COMP_
= 0.8V
V
FSEL
> 2V
V
FSEL
< 0.8V
4.5
1
135
5
3.7
60
3.5
260
V
µA
µA
mA
SYMBOL
CONDITIONS
MIN
TYP
MAX
UNITS
www.maximintegrated.com
Maxim Integrated
│
2
MAX17521
60V, 1A, Dual-Output, High-Efficiency,
Synchronous Step-Down DC-DC Converter
Electrical Characteristics (continued)
(V
IN_
= +24V, V
SGND_
= V
PGND_
= V
FSEL
= 0V, C
IN_
= 2.2μF, C
VCC_
= 1μF, V
EN/UVLO_
= 1.5V, C
SS_
= 0.01μF, FB_ = 0.98 x V
FB-REG
,
COMP_ = unconnected, LX_ = unconnected,
RESET_
= unconnected. 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
ENABLE/UVLO (EN_)
V
EN_R
EN_ Threshold
V
EN_F
V
EN_-
TRUESD
SYMBOL
V
EN_
rising
V
EN_
falling
CONDITIONS
MIN
1.19
1.11
TYP
1.215
1.135
0.75
MAX
1.24
1.16
UNITS
V
V
EN_
falling, true shutdown
V
EN_
= V
IN
= 60V, T
A
= +25°C
V
FSEL
low level
V
FSEL
high level
V
FSEL
= V
CC
, T
A
= +25°C
V
MODE_
low level
V
MODE_
high level
V
MODE
= V
CC
, T
A
= +25°C
6V < V
IN_
< 12V, 0mA < I
VCC_
< 10mA
12V < V
IN_
< 60V, 0mA < I
VCC_
< 2mA
V
CC_
= 4.3V, V
IN_
= 12V
V
IN_
= 4.5V, I
VCC_
= 5mA
V
CC_
rising
V
CC_
falling
I
LX_
= 0.5A
(sourcing)
I
LX_
= 0.5A
(sinking)
T
A
= +25°C
T
A
= T
J
= +125°C (Note 3)
T
A
= +25°C
T
A
= T
J
= +125°C (Note 3)
2.5
2
-2.5
EN_ Input Leakage Current
FREQUENCY SELECTOR (FSEL)
FSEL Threshold
FSEL Input Leakage Current
MODE SELECTOR (MODE_)
MODE_ Threshold
MODE_ Input Leakage Current
LDO (V
CC_
)
V
CC_
Output Voltage Range
V
CC_
Current Limit
V
CC_
Dropout
V
CC_
UVLO
POWER MOSFETs
High-Side_ pMOS
On-Resistance
Low-Side_ nMOS
On-Resistance
LX_ Leakage Current
SOFT-START (SS_)
Charging Current_
FEEDBACK (FB)
FB Regulation Voltage
FB Input Bias Current
IEN_
V
FSELR
V
FSELF
I
FSEL
V
MODE_ R
V
MODE_ F
I
MODE_
300
0.8
+2.5
1.9
300
nA
V
µA
V
nA
V
VCC_
I
VCC_ -MAX
V
CC_-DO
V
VCC_-UVR
V
CC_ -UVF
4.65
17
4.1
3.85
3.55
5
40
5.35
80
mA
V
V
4
3.7
0.6
0.2
4.15
3.85
0.8
1.2
0.35
0.45
3
V
R
DS_ -ONH
R
DS_ -ONL
I
LX_LKG
Ω
Ω
μA
V
EN_
= 0V, T
A
= +25°C, V
LX_
=
(V
PGND_
+ 1V) to (V
IN_
– 1V)
V
SS_
= 0.5V
MODE_ = SGND_
MODE_ = unconnected
V
FB
= 0.9V
4.7
0.885
5
0.9
0.915
15
I
SS_
5.3
0.915
100
μA
V
FB_REG
I
FB
V
nA
www.maximintegrated.com
Maxim Integrated
│
3
MAX17521
60V, 1A, Dual-Output, High-Efficiency,
Synchronous Step-Down DC-DC Converter
Electrical Characteristics (continued)
(V
IN_
= +24V, V
SGND_
= V
PGND_
= V
FSEL
= 0V, C
IN_
= 2.2μF, C
VCC_
= 1μF, V
EN/UVLO_
= 1.5V, C
SS_
= 0.01μF, FB_ = 0.98 x V
FB-REG
,
COMP_ = unconnected, LX_ = unconnected,
RESET_
= unconnected. 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
OUTPUT VOLTAGE (V
OUT
)
Output Voltage Range
V
OUT
V
FSEL
> 2V; no load (Note 3)
V
FSEL
< 0.8V; no load (Note 3)
0.92
0.92
0.92 x
V
IN
0.96 x
V
IN
590
33
33
0.5
650
55
55
0.545
V
SYMBOL
CONDITIONS
MIN
TYP
MAX
UNITS
TRANSCONDUCTANCE AMPLIFIER (COMP)
Transconductance
COMP_ Source Current
COMP_ Sink Current
Current Sense Transresistance
CURRENT LIMIT
Peak Current Limit Threshold
Runaway Current Limit
Threshold
Sink Current Limit Threshold
PFM Peak Current
TIMINGS
Switching Frequency
V
FB_
Under Voltage Trip Level
to Cause HICCUP
HICCUP Timeout
Minimum On-Time
Maximum Duty Cycle
LX_ Dead Time
t
ON_ _MIN
D
MAX_
V
FB_
= 0.98 x V
FB_ -REG
V
FSEL
> 2V
V
FSEL
< 0.8V
92
96
f
SW_
V
FB_
> V
OUT_-HICF
V
FB_
<V
OUT_-HICF
V
OUT_-HICF
V
FSEL
> 2V
V
FSEL
< 0.8V
V
FSEL
> 2V
510
280
280
68.5
560
300
300
70
4096
85
94
97
5
120
96
98
600
320
320
72.5
%
Cycles
ns
%
ns
kHz
I
PEAK_-LIMIT
I
RUNAWAY
_-LIMIT
GM
_
I
COMP_ _SRC
I
COMP_
_SINK
I
COMP_
= ±2.5μA
510
19
19
0.455
μS
μA
μA
Ω
R
CS_
1.35
1.45
V
MODE_
< 0.8V
V
MODE_
> 2V
V
MODE_
> 2V
0.2
1.6
1.85
0.65
0
0.3
1.85
2.05
A
A
A
A
I
SINK-LIMIT
I
PFM_
0.4
A
V
SS_
> 0.95V (soft-start is done)
www.maximintegrated.com
Maxim Integrated
│
4
MAX17521
60V, 1A, Dual-Output, High-Efficiency,
Synchronous Step-Down DC-DC Converter
Electrical Characteristics (continued)
(V
IN_
= +24V, V
SGND_
= V
PGND_
= V
FSEL
= 0V, C
IN_
= 2.2μF, C
VCC_
= 1μF, V
EN/UVLO_
= 1.5V, C
SS_
= 0.01μF, FB_ = 0.98 x V
FB-REG
,
COMP_ = unconnected, LX_ = unconnected,
RESET_
= unconnected. 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
SYMBOL
V
SYNC_R
V
SYNC_F
I
SYNC
T
SYNC
f
SYNC
f
SW
= 300kHz or 560kHz
V
SYNC
= 5V ; T
A
= +25°C
50
1.1x
f
SW
1.4x
f
SW
0.02
0.5
90.5
93.5
92.5
95.5
1024
94.5
97.5
2
300
CONDITIONS
MIN
TYP
MAX
0.8
UNITS
FREQUENCY SYNCHRONIZATIONS (SYNC)
SYNC Threshold
SYNC Input Leakage Current
SYNC Pulse Duration
SYNC Frequency
RESET_
RESET_
Output Level Low
RESET_
Output Leakage
Current High
V
OUT_
Threshold for
RESET
Falling
V
OUT_
Threshold for
RESET_
Rising
RESET
_ Delay After FB_
Reaches 95% Regulation
THERMAL SHUTDOWN
Thermal-Shutdown Threshold
Thermal-Shutdown Hysteresis
Temperature rising
165
10
°C
°C
I
RESET_
= 1mA
V
FB_
= 1.01 x V
FB_-REG
, T
A
= 25°C
V
OUT_
-OKF V
FB_
falling
V
OUT_
-OKR V
FB_
rising
V
μA
%
%
Cycles
V
nA
ns
kHz
Note 2:
Limits are 100% tested at TA = +25°C. Limits over the operating temperature range and relevant supply voltage range are
摘要：以正交频分复用(0FDM)为代表的多载波传输技术可以大大提高系统容量，因而受到人们的广泛关注并得到广泛的应用。介绍了OFDM的原理及其在无线局域网中的应用情况，总结了0FDM的特点。并针对无线信道的特点介绍了一种可靠的自适应传输方案。
关键词：OFDM；无线局域网；自适应传输；通信
l 引言
近年来，正交频分复用(0FDM)技术因其可有效对抗多径干扰(IsI)和提高系统容量而受到人...[详细]
stm32/stm8
