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PDF MAX5090B Data sheet ( Hoja de datos )
| Número de pieza | MAX5090B | |
| Descripción | High-Efficiency MAXPower Step-Down DC-DC Converters | |
| Fabricantes | Maxim Integrated Products | |
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19-3872; Rev 0; 3/06
EVAALVUAAILTAIOBNLEKIT
2A, 76V, High-Efficiency
MAXPower Step-Down DC-DC Converters
General Description
The MAX5090A/B/C easy-to-use, high-efficiency, high-
voltage step-down DC-DC converters operate from an
input voltage up to 76V, and consume only 310µA qui-
escent current at no load. This pulse-width-modulated
(PWM) converter operates at a fixed 127kHz 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 MAX5090
includes internal frequency compensation simplifying
circuit implementation. The device can also be syn-
www.DcahtraoSnhiezeetd4Uw.ciothmexternal system clock frequency in a
noise-sensitive application. The MAX5090 uses an
internal low on-resistance and a high-voltage DMOS
transistor to obtain high efficiency and reduce overall
system cost. This device includes undervoltage lock-
out, cycle-by-cycle current limit, hiccup-mode output
short-circuit protection, and overtemperature shutdown.
The MAX5090 delivers up to 2A output current. External
shutdown is included, featuring 19µA (typ) shutdown
current. The MAX5090A/MAX5090B versions have fixed
output voltages of 3.3V and 5V, respectively, while the
MAX5090C features an adjustable 1.265V to 11V output
voltage.
The MAX5090 is available in a space-saving 16-pin thin
QFN package (5mm x 5mm) and operates over the
automotive temperature range (-40°C to +125°C).
Applications
Automotive
Industrial
Distributed Power
Typical Operating Circuit
Features
♦ Wide Input Voltage Range: 6.5V to 76V
♦ Fixed (3.3V, 5V) and Adjustable (1.265V to 11V)
Output-Voltage Versions
♦ 2A Output Current
♦ Efficiency Up to 92%
♦ Internal 0.26Ω High-Side DMOS FET
♦ 310µA Quiescent Current at No Load
♦ 19µA Shutdown Current
♦ Internal Frequency Compensation
♦ Fixed 127kHz Switching Frequency
♦ External Frequency Synchronization
♦ Thermal Shutdown and Short-Circuit Current Limit
♦ -40°C to +125°C Automotive Temperature Range
♦ 16-Pin (5mm x 5mm) Thin QFN Package
♦ Capable of Dissipating 2.67W at +70°C
Ordering Information
PART
TEMP
RANGE
PIN-
PACKAGE*
OUTPUT
VOLTAGE
(V)
MAX5090AATE+ -40°C to +125°C 16 TQFN-EP**
3.3
MAX5090AATE -40°C to +125°C 16 TQFN-EP**
3.3
MAX5090BATE+ -40°C to +125°C 16 TQFN-EP**
5.0
MAX5090BATE -40°C to +125°C 16 TQFN-EP**
5.0
Ordering Information continued at end of data sheet.
*The package code is T1655-3.
**EP = Exposed pad.
+Denotes lead-free package.
Pin Configuration
VIN
7.5V TO 76V
CIN
68µF
CBYPASS
0.47µF
RIN
10Ω
VIN
ON/OFF
DRAIN
LX
MAX5090B
SYNC
SGND
PGND
BST
FB
SS
VD
CBST
0.22µF
100µH
D1
PDS5100H
3.3µF
CSS
0.047µF
VOUT
5V/2A
COUT
100µF
TOP VIEW
12 11 10 9
DRAIN 13
DRAIN 14
N.C. 15
N.C. 16
EP
MA5090
1234
8 FB
7 SS
6 SYNC
5 VD
TQFN
________________________________________________________________ Maxim Integrated Products 1
For pricing, delivery, and ordering information, please contact Maxim/Dallas Direct! at
1-888-629-4642, or visit Maxim’s website at www.maxim-ic.com.
1 page  
2A, 76V, High-Efficiency MAXPower Step-Down
DC-DC Converters
Typical Operating Characteristics (continued)
(VIN = 12V, VON/OFF =12V, TA = TJ = -40°C to +125°C, unless otherwise noted. Typical values are at TA = +25°C. See the Typical
Operating Circuit, if applicable.)
OUTPUT CURRENT LIMIT vs. TEMPERATURE
(MAX5090BATE)
4.0
VOUT = 5V
5% DROP IN VOUT
3.5 PULSED OUTPUT LOAD
OUTPUT CURRENT LIMIT vs. INPUT VOLTAGE
(MAX5090AATE)
7.0
VOUT = 3.3V
5% DROP IN VOUT
6.0 PULSED OUTPUT LOAD
OUTPUT CURRENT LIMIT vs. INPUT VOLTAGE
(MAX5090BATE)
7.0
VOUT = 5V
5% DROP IN VOUT
6.0 PULSED OUTPUT LOAD
3.0
www.DataSheet4U.com
2.5
5.0
4.0
5.0
4.0
2.0 3.0 3.0
1.5 2.0 2.0
1.0
-50 -25 0 25 50 75 100 125 150
AMBIENT TEMPERATURE (°C)
1.0
6.5 16 26 36 46 56 66 76
INPUT VOLTAGE (V)
1.0
6.5 16 26 36 46 56 66 76
INPUT VOLTAGE (V)
NO-LOAD SUPPLY CURRENT vs. TEMPERATURE
(MAX5090AATE)
600
VOUT = 3.3V
550
500
450
400
350
NO-LOAD SUPPLY CURRENT vs. INPUT VOLTAGE
(MAX5090AATE)
600
VOUT = 3.3V
550
500
450
400
350
SHUTDOWN CURRENT vs. TEMPERATURE
(MAX5090AATE)
30
VOUT = 3.3V
26
22
18
14
300
-50 -25 0 25 50 75 100 125 150
AMBIENT TEMPERATURE (°C)
300
6.5 16 26 36 46 56 66 76
INPUT VOLTAGE (V)
10
-50 -25 0 25 50 100 125 150 175
AMBIENT TEMPERATURE (°C)
SHUTDOWN CURRENT
vs. INPUT VOLTAGE
45
40 VOUT = 3.3V
35
30
25
20
15
10
5
OUTPUT VOLTAGE
vs. INPUT VOLTAGE
13
MAX5090CATE
VOUT = 11V
11 VON/OFF = VIN
9
IOUT = 2A
IOUT = 1A
6
IOUT = 0A
3
LOAD-TRANSIENT RESPONSE
(MAX5090AATE)
MAX5090 toc18
VOUT = 3.3V
A
B
0
6.5 16
26 36 46 56 66 76
0
5 6 7 8 9 10 11 11.5 12 12.5 13
400µs/div
INPUT VOLTAGE (V)
VIN (V)
A: VOUT, 200mV/div, AC-COUPLED
B: IOUT, 1A/div, 1A TO 2A
_______________________________________________________________________________________
5
5 Page 
2A, 76V, High-Efficiency MAXPower Step-Down
DC-DC Converters
Thermal-overload protection is intended to protect the
MAX5090 in the event of a fault condition. For normal
circuit operation, do not exceed the absolute maximum
junction temperature rating of TJ = +150°C.
Setting the Output Voltage
The MAX5090A/MAX5090B have preset output volt-
ages of 3.3V and 5.0V, respectively. Connect FB to
VOUT for the preset output voltage (Figure 1).
The MAX5090C offers an adjustable output voltage. Set
the output voltage with a resistive divider connected
www.DfraotmaShtheeet4cUir.ccuoimt’s output to ground (Figure 2). Connect
the center node of the divider to FB. Choose R4 less
than 15kΩ, then calculate R3 as follows:
R3 = (VOUT − 1.228) x R4
1.228
The MAX5090 features internal compensation for opti-
mum closed-loop bandwidth and phase margin.
Because of the internal compensation, the output must
be sensed immediately after the primary LC.
Inductor Selection
The MAX5090 is a fixed-frequency converter with fixed
internal frequency compensation. The internal fixed
compensation assumes a 100µH inductor and 100µF
output capacitor with 50mΩ ESR. It relies on the loca-
tion of the double LC pole and the ESR zero frequency
for proper closed-loop bandwidth and the phase mar-
gin at the closed-loop unity-gain frequency. See Table
2 for proper component values. Usually, the choice of
an inductor is guided by the voltage difference
between VIN and VOUT, the required output current and
the operating frequency of the circuit. However, use the
recommended inductors in Table 2 to ensure stable
operation with optimum bandwidth.
Use an inductor with a maximum saturation current rat-
ing greater than or equal to the maximum peak current
limit (5A). Use inductors with low DC resistance for a
higher efficiency converter.
Selecting a Rectifier
The MAX5090 requires an external Schottky rectifier as
a freewheeling diode. Connect this rectifier close to the
device using short leads and short PC board traces.
The rectifier diode must fully conduct the inductor cur-
rent when the power FET is off to have a full rectifier
function. Choose a rectifier with a continuous current
Table 1. Diode Selection
VIN (V)
6.5 to 36
6.5 to 56
6.5 to 76
DIODE PART
NUMBER
B340LB
RB051L-40
MBRS340T3
MBRM560
RB095B-60
MBRD360T4
50SQ80
PDS5100H
MANUFACTURER
Diodes Inc.
Central Semiconductor
ON Semiconductor
Diodes Inc.
Central Semiconductor
ON Semiconductor
IR
Diodes Inc.
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 for-
ward-voltage Schottky rectifier for proper operation and
high efficiency. Avoid higher than necessary reverse-
voltage Schottky rectifiers that have higher forward-volt-
age drops. Use a Schottky rectifier with forward-voltage
drop (VF) less than 0.55V and 0.45V at +25°C and
+125°C, respectively, and at maximum load current to
avoid forward biasing of the internal parasitic body
diode (LX to ground). See Figure 3 for forward-voltage
drop vs. temperature of the internal body diode of the
MAX5090. Internal parasitic body-diode conduction
may cause improper operation, excessive junction tem-
perature 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
reflecting back to the source dictate the capacitance
requirement. The MAX5090 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:
______________________________________________________________________________________ 11
11 Page | ||
| Páginas | Total 17 Páginas | |
| PDF Descargar | [ Datasheet MAX5090B.PDF ] | |
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