|
|
PDF MAX17681 Data sheet ( Hoja de datos )
| Número de pieza | MAX17681 | |
| Descripción | Iso-Buck DC-DC Converter | |
| Fabricantes | Maxim Integrated | |
| Logotipo |  |
|
Hay una vista previa y un enlace de descarga de MAX17681 (archivo pdf) en la parte inferior de esta página. Total 18 Páginas | ||
|
No Preview Available !
MAX17681
4.5V to 42V Input, High-Efficiency,
Iso-Buck DC-DC Converter
General Description
The MAX17681 is a high-voltage, high-efficiency, iso-
buck DC-DC converter designed to provide isolated
power up to 3W. The device operates over a wide 4.5V
to 42V input and uses primary-side feedback to regulate
the output voltage.
The MAX17681 uses peak-current-mode control. The
low-resistance, on-chip MOSFETs ensure high efficiency
at full load while simplifying the PCB layout.
The device is available in a compact 10-pin (3mm x 2mm)
TDFN package. Simulation models are available.
Applications
●● Isolated Fieldbus Interfaces
●● PLC I/O Modules
●● Smart Meters
●● Isolated Power Supplies in Medical Equipment
●● Floating Power Supply Generation
Ordering Information appears at end of data sheet.
Application Circuit
Benefits and Features
●● Reduces External Components and Total Cost
• No Opto-Coupler
• Synchronous Primary Operation
• All-Ceramic Capacitors, Compact Layout
●● Reduces Number of DC-DC Regulators to Stock
• Wide 4.5V to 42V Input
• 0.9V to 0.96 x VIN Primary Output Voltage
• Delivers Up to 3W Output Power
●● Reduces Power Dissipation
• Peak Efficiency > 90%
• 0.9μA (typ) Shutdown Current
●● Operates Reliably in Adverse Industrial Environments
• Peak and Sink Current-Limit Protection
• ±1.7% Feedback Accuracy
• Programmable EN/UVLO Threshold
• Adjustable Soft-Start
• Overtemperature Protection
• -40°C to +125°C Operation
VIN
17V TO 32V
C1
1µF
VIN
EN/UVLO
LX
PGND
VCC
C3
GND
1µF MAX17681
SS
C4
33nF
FB
C6
680pF
COMP
R3
4.75kΩ
C5
33nF
RESET
T1 D1
1:2.4
NPRI
NSEC
VOUT
24V, 100mA
C7
2.2µF
R4
49.9Ω
Z1
R1
105kΩ
R2
10kΩ
C2
10uF
C8
1nF
19-7053; Rev 1; 10/15
1 page  
MAX17681
4.5V to 42V Input, High-Efficiency,
Iso-Buck DC-DC Converter
Typical Operating Characteristics
(VIN = 24V, VGND = VPGND = 0V, CVIN = 1μF, CVCC = 1μF, VEN = 1.5V, CSS = 33nF, VFB = 0.98 x VPRI, TA = +25°C, unless otherwise
noted.)
100 EFFICIENCY vs. LOAD CURRENT toc1
90
80
VIN = 17V
70
VIN = 24V
60 VIN = 32V
50
40
0
FIGURE 9
APPLICATION
CIRCUIT
10 20 30 40 50 60 70 80 90 100
LOAD CURRENT (mA)
OUTPUT VOLTAGE
8
REGULATION
toc2
6
4
2
VIN = 32V
VIN = 24V
0
-2 VIN = 17V
VIN = 19V
-4
FIGURE 9
APPLICATION
CIRCUIT
-6
0 10 20 30 40 50 60 70 80 90 100
LOAD CURRENT (mA)
FEEDBACK VOLTAGE
910
VS. TEMPERATURE
toc3
905
900
895
890
-40 -20
0 20 40 60 80 100 120
TEMPERATURE (°C)
EN/UVLO THRESHOLD VOLTAGE
1.26
VS. TEMPERATURE
toc4
SHUTDOWN CURRENT
2.0
VS. TEMPERATURE
toc5
NO LOAD SUPPLY CURRENT
2.2
VS. TEMPERATURE
toc6
1.22 RISING
1.18
1.14
FALLING
1.10
-40 -20
0 20 40 60 80 100 120
TEMPERATURE (°C)
1.7
1.4
1.1
0.8
0.5
-40 -20
0 20 40 60 80 100 120
TEMPERATURE (°C)
2.1
2.0
1.9
1.8
-40 -20
0 20 40 60 80 100 120
TEMPERATURE (°C)
SWITCHING FREQUENCY
210
VS. TEMPERATURE
toc7
205
200
195
190
-40 -20
0 20 40 60 80 100 120
TEMPERATURE (°C)
SWITCH CURRENT LIMIT
1.9
VS. TEMPERATURE
toc8
1.8 RUNAWAY CURRENT LIMIT
1.7
PEAK CURRENT LIMIT
1.6
1.5
1.4
1.3
1.2 SINK CURRENT LIMIT
1.1
1.0
-40 -20
0 20 40 60 80 100 120
TEMPERATURE (°C)
www.maximintegrated.com
Maxim Integrated │ 5
5 Page 
MAX17681
4.5V to 42V Input, High-Efficiency,
Iso-Buck DC-DC Converter
Primary Output Voltage Selection
Primary output voltage is regulated by the MAX17681
control loop. The primary output voltage can be calculated
by using the equation:
=VPRI DMAX × VIN_MIN
where DMAX is the maximum duty cycle of the converter
and VIN_MIN is the minimum input voltage. Maximum duty
cycle should be in the range of 0.4 to 0.6 for ideal iso-buck
operation.
Adjusting the Primary Output Voltage
The primary output voltage is set with a resistor-divider
from primary output to FB to GND (see Figure 5). Choose
R2 in the range of 10k to 49.9k and calculate R1 using
the equation:
R1
=R2 ×
VPRI
0.9
−
1
Turns Ratio Selection
Neglecting diode drop VD, transformer resistances, and
leakage inductance, the iso-buck output voltage VOUT is
proportional to the primary output voltage VPRI. The turns
ratio (K) is given by the equation:
NSEC = VOUT + VD
NPRI
VPRI
K = NSEC
NPRI
Turns ratio can be adjusted to match with the readily
available off-the-shelf transformer turns ratio by adjusting
the primary output voltage.
LX
MAX17681
FB
D1
NPRI
NSEC
+
- COUT
+
R1 CPRI
-
R2
Primary Inductance Selection
Primary inductance value determines the ripple current in
the transformer. The required primary inductance is given
by the equation:
LPRI= 7 × VPRI
where LPRI is the primary inductance in μH and VPRI is
the primary output voltage.
The primary ripple current can be calculated using the
equation:
∆I
VPRI
=
×
1 −
VPRI
VIN
fSW × LPRI
where LPRI is the primary inductance in H, fSW is the
switching frequency in Hz, VPRI is the primary output volt-
age, VIN is the input voltage.
Winding Peak and RMS Currents
Windings peak and RMS current ratings should be speci-
fied for selecting the iso-buck transformer.
Primary and secondary winding peak currents are given
by the equations:
IPK _PR=I
(IOUT
×
K)
+
∆I
2
IPK _SEC
=
2 × IOUT
(1− D)
D = VPRI
VIN
where IOUT is the load current, K is the turns ratio, D is
the duty cycle, and ∆I is the primary ripple current.
Primary RMS current is the sum of the high-side and low-
side switch RMS currents.
High-side switch RMS current:
IHS_RMS
=
D× (IOUT
× K) 2
+
∆I2
12
Figure 5. Adjusting the Primary Output Voltage
www.maximintegrated.com
Maxim Integrated │ 11
11 Page | ||
| Páginas | Total 18 Páginas | |
| PDF Descargar | [ Datasheet MAX17681.PDF ] | |
Hoja de datos destacado
| Número de pieza | Descripción | Fabricantes |
| MAX17681 | Iso-Buck DC-DC Converter | Maxim Integrated |
| Número de pieza | Descripción | Fabricantes |
| SLA6805M | High Voltage 3 phase Motor Driver IC. |
 Sanken |
| SDC1742 | 12- and 14-Bit Hybrid Synchro / Resolver-to-Digital Converters. |
 Analog Devices |
|
DataSheet.es es una pagina web que funciona como un repositorio de manuales o hoja de datos de muchos de los productos más populares, |
| DataSheet.es | 2020 | Privacy Policy | Contacto | Buscar |