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PDF MAX17541G Data sheet ( Hoja de datos )
| Número de pieza | MAX17541G | |
| Descripción | Synchronous Step-Down DC-DC Converter | |
| Fabricantes | Maxim Integrated | |
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MAX17541G
42V, 500mA, Ultra-Small, High-Efficiency,
Synchronous Step-Down DC-DC Converter
General Description
The MAX17541G high-efficiency, high-voltage, synchronous
step-down DC-DC converter with integrated MOSFETs
operates over 4.5V to 42V input. The converter can
deliver up to 500mA and generates output voltages from
0.9V up to 0.92 x VIN. The feedback (FB) voltage is accurate
to within ±1.7% over -40°C to +125°C.
The MAX17541G uses peak-current-mode control with
pulse-width modulation (PWM) and operates with fixed
600kHz switching frequency at any load. The device
is available in a 10-pin (3mm x 2mm) TDFN package.
Simulation models are available.
Applications
● Industrial Process Control
● HVAC and Building Control
● Base Station, VOIP, Telecom
● Home Theatre
● Battery-Powered Equipment
● General-Purpose Point of Load
Benefits and Features
● Reduces External Components and Total Cost
• No Schottky-Synchronous Operation
• All-Ceramic Capacitors, Ultra-Compact Layout
● Reduces Number of DC-DC Regulators to Stock
• Wide 4.5V to 42V Input
• Adjustable 0.9V to 92%VIN Output
• Delivers up to 500mA
● Reduces Power Dissipation
• Peak Efficiency > 90%
• Shutdown Current = 0.9μA (typ)
● Operates Reliably in Adverse Industrial Environments
• Hiccup-Mode Current Limit, Sink Current Limit,
and Autoretry Startup
• Built-In Output-Voltage Monitoring (RESET Pin)
• Programmable EN/UVLO Threshold
• Adjustable Soft-Start and Prebiased Power-Up
• -40°C to +125°C Operation
Ordering Information appears at end of data sheet.
MAX17541G Application Circuit (5V Output, 500mA Maximum Load Current)
VIN
C1 R1
1µF 3.32MΩ
1
JU1 2
3
R2
681k
C2
1µF
C3
3300pF
R3
C9 21.5kΩ
22pF
C5
3300pF
L1
47µH
VIN LX
EN/UVLO
PGND
MAX17541G
GND
VCC
FB/VO
SS
COMP
RESET
L1 = 74404054470 OR
XFL6060-473
RESET
C4
10µF
VOUT
5V, 500mA
R4
82.5kΩ
R5
18.2kΩ
19-7672 Rev 0; 6/15
1 page  
MAX17541G
42V, 500mA, Ultra-Small, High-Efficiency,
Synchronous Step-Down DC-DC Converter
Typical Operating Characteristics
(VIN = 24V, VGND = VPGND = 0V, CVIN = 1μF, CVCC = 1μF, VEN = 1.5V, CSS = 3300pF, VFB = 0.98 x VOUT, LX = unconnected,
RESET = unconnected, TA = TJ = -40°C to +125°C, unless otherwise noted. Typical values are at TA = +25°C. All voltages are referenced
to GND, unless otherwise noted.)
3.3V OUTPUT
EFFICIENCY vs. LOAD CURRENT
100 FIGURE 5 CIRCUIT
90
80
70
VIN = 24V VIN = 36V
60 VIN = 12V
50
40
50 100 150 200 250 300 350 400 450 500
LOAD CURRENT (mA)
5V OUTPUT
EFFICIENCY vs. LOAD CURRENT
100 FIGURE 6 CIRCUIT
90
80
70
VIN = 24V
VIN = 36V
VIN = 12V
60
50
L1 = 74404054470
40
50 100 150 200 250 300 350 400 450 500
LOAD CURRENT (mA)
5V OUTPUT
EFFICIENCY vs. LOAD CURRENT
FIGURE 6 CIRCUIT
100
90
80
70
VIN = 24V
VIN = 36V
VIN = 12V
60
50
L1 = XFL6060-473
40
50 100 150 200 250 300 350 400 450 500
LOAD CURRENT (mA)
3.3V OUTPUT
LOAD AND LINE REGULATION
FIGURE 5 CIRCUIT
3.55
3.50
3.45
3.40 VIN = 24V
3.35
3.30
3.25
3.20 VIN = 12V
3.15
VIN = 36V
3.10
3.05
0
100 200 300 400
LOAD CURRENT (mA)
500
NO-LOAD SWITCHING CURRENT
vs. TEMPERATURE
5.00
4.95
4.90
4.85
4.80
-40 -20
0 20 40 60 80 100 120
TEMPERATURE (°C)
5V OUTPUT
LOAD AND LINE REGULATION
FIGURE 6 CIRCUIT
5.05
5.03
5.01
4.99 VIN = 24V
4.97
4.95
4.93
4.91 VIN = 12V
4.89
VIN = 36V
4.87
0
100 200 300 400
LOAD CURRENT (mA)
500
1.23
1.22
1.21
1.20
1.19
1.18
1.17
1.16
1.15
1.14
1.13
1.12
-40
EN/UVLO THRESHOLD
vs. TEMPERATURE
RISING
THRESHOLD
FALLING
THRESHOLD
-20 0 20 40 60 80 100
TEMPERATURE (°C)
120
SHUTDOWN CURRENT
vs. TEMPERATURE
1.10
1.05
1.00
0.95
0.90
0.85
0.80
0.75
0.70
-40 -20
0 20 40 60 80 100 120
TEMPERATURE (°C)
FEEDBACK VOLTAGE
vs. TEMPERATURE
0.92
0.91
0.90
0.89
0.88
-40 -20
0 20 40 60 80 100 120
TEMPERATURE (°C)
www.maximintegrated.com
Maxim Integrated │ 5
5 Page 
MAX17541G
42V, 500mA, Ultra-Small, High-Efficiency,
Synchronous Step-Down DC-DC Converter
Thermal-Overload Protection
Thermal-overload protection limits total power dissipation
in the device. When the junction temperature of the device
exceeds +165°C, an on-chip thermal sensor shuts down
the device, allowing the device to cool. The thermal sensor
turns the device on again after the junction temperature
cools by 10°C. Soft-start resets during thermal shutdown.
Carefully evaluate the total power dissipation (see the
Power Dissipation section) to avoid unwanted triggering of
the thermal-overload protection in normal operation.
Applications Information
Input Capacitor Selection
The discontinuous input-current waveform of the buck
converter causes large ripple currents in the input capaci-
tor. The switching frequency, peak inductor current, and
the allowable peak-to-peak voltage ripple that reflects
back to the source dictate the capacitance requirement.
The device’s high switching frequency allows the use
of smaller value input capacitors. X7R capacitors are
recommended in industrial applications for their tem-
perature stability. A minimum value of 1μF should be used
for the input capacitor. Higher values help reduce the
ripple on the input DC bus further. In applications where
the source is located distant from the device input, an
electrolytic capacitor should be added in parallel to the
1μF ceramic capacitor to provide necessary damping for
potential oscillations caused by the longer input power
path and input ceramic capacitor.
Inductor Selection
Three key inductor parameters must be specified for
operation with the device: inductance value (L), inductor
saturation current (ISAT), and DC resistance (RDCR). The
output voltage determines the inductor value as follows:
L = 8 x VOUT
where L is in µH.
Select a low-loss inductor closest to the calculated
value with acceptable dimensions and having the lowest
possible DC resistance. The saturation current rating
(ISAT) of the inductor must be high enough to ensure that
saturation can occur only above the peak current-limit
value (IPEAK-LIMIT (typ) = 0.76A for the device).
Output Capacitor Selection
X7R ceramic output capacitors are preferred due to their
stability over temperature in industrial applications. The
output capacitor is usually sized to support a step load
of 50% of the maximum output current in the application,
so the output-voltage deviation is contained to ±3% of the
output-voltage change.
The output capacitance can be calculated as follows:
C OUT=
1 × ISTEP × t RESPONSE
2 ∆VOUT
t RESPONSE
≅
0.33
fC
+
1
fSW
where ISTEP is the load current step, tRESPONSE is the
response time of the controller, ΔVOUT is the allowable out-
put-voltage deviation, fC is the target closed-loop crossover
frequency, and fSW is the switching frequency (600kHz).
Select fC to be 1/12th of fSW. Consider DC bias and aging
effects while selecting the output capacitor.
Soft-Start Capacitor Selection
The device implements adjustable soft-start operation to
reduce inrush current. A capacitor connected from the SS
pin to GND programs the soft-start time. The selected
output capacitance (CSEL) and the output voltage (VOUT)
determine the minimum required soft-start capacitor as
follows:
CSS 30 x 10-6 x CSEL x VOUT
The soft-start time (tSS) is related to the capacitor con-
nected at SS (CSS) by the following equation:
tSS
=
CSS
5.55 x 10-6
Adjusting Output Voltage
The MAX17541G offers an adjustable output voltage from
0.9V to 92%VIN. Set the output voltage with a resistive
voltage-divider connected from the positive terminal of the
output capacitor (VOUT) to GND (see Figure 1). Connect
the center node of the divider to FB. To optimize efficiency
and output accuracy, use the following procedure to
choose the values of R4 and R5:
R4 = 16 x VOUT
where R4 is in kW.
www.maximintegrated.com
Maxim Integrated │ 11
11 Page | ||
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| PDF Descargar | [ Datasheet MAX17541G.PDF ] | |
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