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Número de pieza | MAX5035 | |
Descripción | 1A / 76V / High-Efficiency MAXPower Step-Down DC-DC Converter | |
Fabricantes | Maxim Integrated | |
Logotipo | ||
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AVAILABLE
MAX5035
1A, 76V, High-Efficiency MAXPower
Step-Down DC-DC Converter
General Description
The MAX5035 easy-to-use, high-efficiency, high-volt-
age, step-down DC-DC converter operates from an
input voltage up to 76V and consumes only 270µA qui-
escent current at no load. This pulse-width modulated
(PWM) converter operates at a fixed 125kHz switching
frequency at heavy loads, and automatically switches
to pulse-skipping mode to provide low quiescent cur-
rent and high efficiency at light loads. The MAX5035
includes internal frequency compensation simplifying
circuit implementation. The device uses an internal low-
on-resistance, high-voltage, DMOS transistor to obtain
high efficiency and reduce overall system cost. This
device includes undervoltage lockout, cycle-by-cycle
current limit, hiccup mode output short-circuit protec-
tion, and thermal shutdown.
The MAX5035 delivers up to 1A output current. The out-
put current may be limited by the maximum power dis-
sipation capability of the package. External shutdown is
included, featuring 10µA (typ) shutdown current. The
MAX5035A/B/C versions have fixed output voltages of
3.3V, 5V, and 12V, respectively, while the MAX5035D/E
versions have an adjustable output voltage from 1.25V
to 13.2V.
The MAX5035 is available in space-saving 8-pin SO
and 8-pin plastic DIP packages and operates over the
automotive (-40°C to +125°C) temperature range.
Applications
Automotive Functional Diagrams
Consumer Electronics
Industrial
Distributed Power
Typical Operating Circuit
Features
o Wide 7.5V to 76V Input Voltage Range
o Fixed (3.3V, 5V, 12V) and Adjustable
(1.25V to 13.2V) Versions
o 1A Output Current
o Efficiency Up to 94%
o Internal 0.4Ω High-Side DMOS FET
o 270µA Quiescent Current at No Load, 10µA
Shutdown Current
o Internal Frequency Compensation
o Fixed 125kHz Switching Frequency
o Thermal Shutdown and Short-Circuit Current
Limit
o 8-Pin SO and PDIP Packages
OOrrddeerriinngg IInnffoorrmmaattiioonn
PART
PIN-
OUTPUT
TEMP RANGE
PACKAGE
VOLTAGE
(V)
MAX5035AUSA
0°C to +85°C 8 SO
MAX5035AUPA
MAX5035AASA
0°C to +85°C 8 PDIP
-40°C to +125°C 8 SO
3.3
MAX5035AASA/V+ -40°C to +125°C 8 SO
MAX5035BUSA
0°C to +85°C 8 SO
MAX5035BUPA
MAX5035BASA
0°C to +85°C 8 PDIP
-40°C to +125°C 8 SO
5.0
MAX5035BASA/V+ -40°C to +125°C 8 SO
/V denotes an automotive qualified part.
+Denotes a lead(Pb)-free/RoHS-compliant package.
Ordering Information continued at end of data sheet.
Pin Configuration
VIN
7.5V TO 76V
68µF
VIN BST
0.1µF
MAX5035
R1 LX
ON/OFF
100µH
D1
50SQ100
ON FB
R2 VD
Pin
OFF
Configurations
SGND
appear
GND
at end
of
da0t.1aµFsheet.
VOUT
5V
68µF
Functional Diagrams continued at end of data sheet.
UCSP is a trademark of Maxim Integrated Products, Inc.
TOP VIEW
BST 1
VD 2
SGND 3
FB 4
MAX5035
8 LX
7 VIN
6 GND
5 ON/OFF
SO/PDIP
For pricing, delivery, and ordering information, please contact Maxim Direct
at 1-888-629-4642, or visit Maxim’s website at www.maximintegrated.com.
19-2988; Rev 5; 5/11
1 page MAX5035
1A, 76V, High-Efficiency MAXPower
Step-Down DC-DC Converter
ELECTRICAL CHARACTERISTICS (MAX5035_A_ _) (continued)
(VIN = +12V, VON/OFF = +12V, IOUT = 0, TA = TJ = -40°C to +125°C, unless otherwise noted. Typical values are at TA = +25°C. See
the Typical Application Circuit.) (Note 2)
PARAMETER
SYMBOL
CONDITIONS
MIN TYP MAX UNITS
PACKAGE THERMAL CHARACTERISTICS
Thermal Resistance
(Junction to Ambient)
SO package (JEDEC 51)
θJA
DIP package (JEDEC 51)
170
°C/W
110
THERMAL SHUTDOWN
Thermal-Shutdown Junction
Temperature
TSH
+160
°C
Thermal-Shutdown Hysteresis
THYST
20 °C
Note 1: Switch current at which current limit is activated.
Note 2: All limits at -40°C are guaranteed by design, not production tested.
Typical Operating Characteristics
(VIN = 12V, VON/OFF = 12V, TA = -40°C to +125°C, unless otherwise noted. Typical values are at TA = +25°C. See the Typical
Application Circuit, if applicable.)
VOUT vs. TEMPERATURE
(MAX5035AASA, VOUT = 3.3V)
3.40
IOUT = 0.1A
3.36
IOUT = 1A
3.32
3.28
3.24
VOUT vs. TEMPERATURE
(MAX5035DASA, VOUT = 5V)
5.20
5.15
5.10
5.05 IOUT = 0.1A
5.00
4.95
IOUT = 1A
4.90
4.85
LINE REGULATION
(MAX5035AASA, VOUT = 3.3V)
3.40
IOUT = 0.1A
3.36
IOUT = 1A
3.32
3.28
3.24
3.20
-50 -25
0 25 50 75 100 125 150
TEMPERATURE (°C)
4.80
-50 -25
0 25 50 75 100 125 150
TEMPERATURE (°C)
3.20
5
20 35 50 65
INPUT VOLTAGE (V)
80
LINE REGULATION
(MAX5035DASA, VOUT = 5V)
5.20
5.15
5.10
5.05 IOUT = 0.1A
5.00
4.95 IOUT = 1A
4.90
4.85
4.80
5
20 35 50 65
INPUT VOLTAGE (V)
80
Maxim Integrated
LOAD REGULATION
(MAX5035AASA, VOUT = 3.3V)
3.40
VIN = 76V
3.36
VIN = 7.5V, 24V
3.32
3.28
3.24
3.20
0
200 400 600 800 1000
ILOAD (mA)
LOAD REGULATION
(MAX5035DASA, VOUT = 5V)
5.10
5.05
VIN = 24V
VIN = 7.5V
5.00
VIN = 76V
4.95
4.90
0
200 400 600 800 1000
ILOAD (mA)
5
5 Page MAX5035
1A, 76V, High-Efficiency MAXPower
Step-Down DC-DC Converter
The MAX5035 features internal compensation for opti-
mum closed-loop bandwidth and phase margin. With
the preset compensation, it is strongly advised to sense
the output immediately after the primary LC.
Inductor Selection
The choice of an inductor is guided by the voltage dif-
ference between VIN and VOUT, the required output
current, and the operating frequency of the circuit. Use
an inductor with a minimum value given by:
L = (VIN − VOUT ) × D
0.3 × IOUTMAX × fSW
where:
D = VOUT
VIN
IOUTMAX is the maximum output current required, and
fSW is the operating frequency of 125kHz. Use an induc-
tor with a maximum saturation current rating equal to at
least the peak switch current limit (ILIM). Use inductors
with low DC resistance for higher efficiency.
Selecting a Rectifier
The MAX5035 requires an external Schottky rectifier as
a freewheeling diode. Connect this rectifier close to the
device using short leads and short PC board traces.
Choose a rectifier with a continuous current rating
greater than the highest expected output current. Use a
rectifier with a voltage rating greater than the maximum
expected input voltage, VIN. Use a low forward-voltage
Schottky rectifier for proper operation and high efficien-
cy. Avoid higher than necessary reverse-voltage
Schottky rectifiers that have higher forward-voltage
drops. Use a Schottky rectifier with forward-voltage
Table 1. Diode Selection
VIN (V) DIODE PART NUMBER
15MQ040N
7.5 to 36
B240A
B240
MBRS240, MBRS1540
30BQ060
7.5 to 56
B360A
CMSH3-60
MBRD360, MBR3060
7.5 to 76
50SQ100, 50SQ80
MBRM5100
MANUFACTURER
IR
Diodes, Inc.
Central Semiconductor
ON Semiconductor
IR
Diodes, Inc.
Central Semiconductor
ON Semiconductor
IR
Diodes, Inc.
Maxim Integrated
drop (VFB) less than 0.45V at +25°C and maximum load
current to avoid forward biasing of the internal body
diode (LX to ground). Internal body diode conduction
may cause excessive junction temperature rise and
thermal shutdown. Use Table 1 to choose the proper
rectifier at different input voltages and output current.
Input Bypass Capacitor
The discontinuous input-current waveform of the buck
converter causes large ripple currents in the input
capacitor. The switching frequency, peak inductor cur-
rent, and the allowable peak-to-peak voltage ripple that
reflects back to the source dictate the capacitance
requirement. The MAX5035 high switching frequency
allows the use of smaller-value input capacitors.
The input ripple is comprised of ∆VQ (caused by the
capacitor discharge) and ∆VESR (caused by the ESR of
the capacitor). Use low-ESR aluminum electrolytic
capacitors with high ripple-current capability at the input.
Assuming that the contribution from the ESR and capaci-
tor discharge is equal to 90% and 10%, respectively, cal-
culate the input capacitance and the ESR required for a
specified ripple using the following equations:
where :
ESRIN
=
∆VESR
⎛
⎝⎜
IOUT
+
∆IL
2
⎞
⎠⎟
CIN
=
IOUT ×
∆VQ
D (1− D)
× fSW
∆IL
=
(VIN − VOUT ) × VOUT ,
VIN × fSW × L
D = VOUT
VIN
IOUT is the maximum output current of the converter
and fSW is the oscillator switching frequency (125kHz).
For example, at VIN = 48V, VOUT = 3.3V, the ESR and
input capacitance are calculated for the input peak-to-
peak ripple of 100mV or less yielding an ESR and
capacitance value of 80mΩ and 51µF, respectively.
Low-ESR, ceramic, multilayer chip capacitors are recom-
mended for size-optimized application. For ceramic
capacitors, assume the contribution from ESR and capaci-
tor discharge is equal to 10% and 90%, respectively.
The input capacitor must handle the RMS ripple current
without significant rise in temperature. The maximum
capacitor RMS current occurs at about 50% duty cycle.
11
11 Page |
Páginas | Total 17 Páginas | |
PDF Descargar | [ Datasheet MAX5035.PDF ] |
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