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PDF MAX5066 Data sheet ( Hoja de datos )
| Número de pieza | MAX5066 | |
| Descripción | Synchronous Buck Controller | |
| Fabricantes | Maxim Integrated Products | |
| Logotipo |  |
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19-3661; Rev 1; 8/05
EVAALVUAAILTAIOBNLEKIT
Configurable, Single-/Dual-Output, Synchronous
Buck Controller for High-Current Applications
General Description
The MAX5066 is a two-phase, configurable single- or
dual-output buck controller with an input voltage range of
4.75V to 5.5V or from 5V to 28V. Each phase of the
MAX5066 is designed for 180° operation. A mode pin
allows for a dual-output supply or connecting two phases
together for a single-output, high-current supply. Each
output channel of the MAX5066 drives n-channel
MOSFETs and is capable of providing more than 25A of
load current. The MAX5066 uses average current-mode
control with a switching frequency up to 1MHz per phase
where each phase is 180° out of phase with respect to
the other. Out-of-phase operation results in significantly
reduced input capacitor ripple current and output volt-
age ripple in dual-phase, single-output voltage applica-
tions. Each buck regulator output has its own high-
performance current and voltage-error amplifier that can
be compensated for optimum output filter L-C values and
transient response.
The MAX5066 offers two enable inputs with accurate
turn-on thresholds to allow for output voltage sequencing
of the two outputs. The device’s switching frequency can
be programmed from 100kHz to 1MHz with an external
resistor. The MAX5066 can be synchronized to an exter-
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nal clock. Each output voltage is adjustable from 0.61V to
5.5V. Additional features include thermal shutdown, “hic-
cup mode” short-circuit protection. Use the MAX5066
with adaptive voltage positioning for applications that
require a fast transient response, or accurate output volt-
age regulation.
The MAX5066 is available in a thermally enhanced 28-pin
TSSOP package capable of dissipating 1.9W. The device
is rated for operation over the -40°C to +85°C extended,
or -40°C to +125°C automotive temperature range.
Applications
High-End Desktop Computers
Graphics Cards
Networking Systems
Point-of-Load High-Current/High-Density
Telecom DC-DC Regulators
RAID Systems
Features
♦ 4.75V to 5.5V or 5V to 28V Input
♦ Dual-Output Synchronous Buck Controller
♦ Configurable for Two Separate Outputs or One
Single Output
♦ Each Output is Capable of Up to 25A Output
Current
♦ Average Current-Mode Control Provides Accurate
Current Limit
♦ 180° Interleaved Operation Reduces Size of Input
Filter Capacitors
♦ Limits Reverse Current Sinking When Operated in
Parallel Mode
♦ Each Output is Adjustable from 0.61V to 5.5V
♦ Independently Programmable Adaptive Voltage
Positioning
♦ Independent Shutdown for Each Output
♦ 100kHz to 1MHz per Phase Programmable
Switching Frequency
♦ Oscillator Frequency Synchronization from
200kHz to 2MHz
♦ Hiccup Mode Overcurrent Protection
♦ Overtemperature Shutdown
♦ Thermally Enhanced 28-Pin TSSOP Package
Capable of Dissipating 1.9W
♦ Operates Over -40°C to +85°C or -40°C to +125°C
Temperature Range
Ordering Information
PART
MAX5066EUI
MAX5066AUI
*Exposed Pad
TEMP RANGE
-40°C to +85°C
-40°C to +125°C
PIN-PACKAGE
28 TSSOP-EP*
28 TSSOP-EP*
________________________________________________________________ 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  
Configurable, Single-/Dual-Output, Synchronous
Buck Controller for High-Current Applications
Typical Operating Characteristics
(Circuit of Figure 6, TA = +25°C, unless otherwise noted. VIN = 12V, VOUT1 = 0.8V, VOUT2 = 1.3V, fSW = 500kHz per phase.)
10,000
OSCILLATOR FREQUENCY vs. RT
CDH = CDL = 0
1000
100
10
0 100 200 300 400 500 600 700 800 900 1000
RT (kΩ)
SUPPLY CURRENT
vs. TEMPERATURE AND FREQUENCY
(VIN = 24V)
16
CDH = CDL = 0
fSW = 1MHz
14
12 fSW = 500kHz
10
8
6 fSW = 250kHz
fSW = 125kHz
4
2
0
-40 -25 -10 5 20 35 50 65 80 95 110 125
TEMPERATURE (°C)
SUPPLY CURRENT
vs. TEMPERATURE AND FREQUENCY
(VIN = 5V)
16
CDH = CDL = 0
fSW = 1MHz
14
12 fSW = 500kHz
10
8
6 fSW = 250kHz
fSW = 125kHz
4
2
0
-40 -25 -10 5 20 35 50 65 80 95 110 125
TEMPERATURE (°C)
SUPPLY CURRENT
vs. OSCILLATOR FREQUENCY
14
CDH_ = CDL_ = 0
13
12
11
10 VIN = 24V
VIN = 12V
9
8
VIN = 5V
7
6
200 400 600 800 1000 1200 1400 1600 1800 2000
FREQUENCY (kHz)
SUPPLY CURRENT
vs. TEMPERATURE AND FREQUENCY
(VIN = 12V)
16
CDH = CDL = 0
fSW = 1MHz
14
12 fSW = 500kHz
10
8
6 fSW = 250kHz
fSW = 125kHz
4
2
0
-40 -25 -10 5 20 35 50 65 80 95 110 125
TEMPERATURE (°C)
SUPPLY CURRENT
vs. DRIVER LOAD CAPACITANCE
100
CLOAD = CDH = CDL
90
80
70
60
50
40
30
20
10
0
0 5 10 15 20 25 30
CLOAD (nF)
REG LOAD REGULATION
5.10
VIN = 24V
5.05
5.00
VIN = 5.5V
4.95
VIN = 12V
4.90
0
10 20 30 40 50 60 70 80 90 100
IREG (mA)
REG LINE REGULATION
5.10
5.08 IREG = 0
5.06
5.04
5.02
5.00
IREG = 60mA
4.98
4.96
5 7 9 11 13 15 17 19 21 23
VIN (V)
REF LOAD REGULATION
3.305
3.300
3.295
3.290
VIN = 5V
VIN = 24V
VIN = 12V
3.285
0
100 200 300 400 500 600 700 800
IREF (µA)
_______________________________________________________________________________________ 5
5 Page 
Configurable, Single-/Dual-Output, Synchronous
Buck Controller for High-Current Applications
Finally, a thermal-shutdown feature protects the device
during thermal faults and shuts down the MAX5066
when the die temperature exceeds +160°C.
Dual-Output/Dual-Phase Select (MODE)
The MAX5066 can operate as a dual-output indepen-
dently regulated buck converter, or as a dual-phase,
single-output buck converter. The MODE input selects
between the two operating modes. When MODE is
grounded (logic low), VEA1 and VEA2 connect to CEA1
and CEA2, respectively (see Figure 1) and the device
operates as a two-output DC-DC converter. When
MODE is connected to REG (logic high), VEA2 is dis-
connected and VEA1 is routed to both CEA1 and CEA2
and the device works as a dual-phase, single-output
buck regulator with each output 180° out of phase with
respect to each other.
Supply Voltage Connections (VIN/VREG)
The MAX5066 accepts a wide input voltage range at IN
of 5V to 28V. An internal linear regulator steps down VIN
to 5.1V (typ) and provides power to the MAX5066. The
output of this regulator is available at REG. For VIN =
4.75V to 5.5V, connect IN and REG together externally.
REG can supply up to 65mA for external loads. Bypass
REG to AGND with a 4.7µF ceramic capacitor for high-
frequency noise rejection and stable operation.
REG supplies the current for both the MAX5066’s inter-
nal circuitry and for the MOSFET gate drivers (when
connected externally to VDD), and can source up to
65mA. Calculate the maximum bias current (IBIAS) for
the MAX5066:
IBIAS = IIN + fSW × (QGQ1 + QGQ2 + QGQ3 + QGQ4 )
where IIN is the quiescent supply current into IN (4mA,
typ), QGQ1, QGQ2, QGQ3, QGQ4 are the total gate
charges of MOSFETs Q1 through Q4 at VGS = 5V (see
Figure 6), and fSW is the switching frequency of each
individual phase.
Low-Side MOSFET Driver Supply (VDD)
VDD is the power input for the low-side MOSFET dri-
vers. Connect the regulator output REG externally to
VDD through an R-C lowpass filter. Use a 1Ω resistor
and a parallel combination of 1µF and 0.1µF ceramic
capacitors to filter out the high peak currents of the
MOSFET drivers from the sensitive internal circuitry.
High-Side MOSFET Drive Supply (BST_)
BST1 and BST2 supply the power for the high-side
MOSFET drivers for output 1 and output 2, respectively.
Connect BST1 and BST2 to VDD through rectifier
diodes D1 and D2 (see Figure 6). Connect a 0.1µF
ceramic capacitor between BST_ and LX_.
Minimize the trace inductance from BST_ and VDD to
rectifier diodes, D1 and D2, and from BST_ and LX_ to
the boost capacitors, C8 and C9 (see Figure 6). This is
accomplished by using short, wide trace lengths.
Undervoltage Lockout (UVLO)/
Power-On Reset (POR)/Soft-Start
The MAX5066 includes an undervoltage lockout
(UVLO) with hysteresis, and a power-on reset circuit for
converter turn-on and monotonic rise of the output volt-
age. The UVLO threshold monitors VREG and is inter-
nally set between 4.0V and 4.5V with 200mV of
hysteresis. Hysteresis eliminates “chattering” during
startup. Most of the internal circuitry, including the
oscillator, turns on when VREG reaches 4.5V. The
MAX5066 draws up to 4mA (typ) of current before
VREG reaches the UVLO threshold.
The compensation network at the current-error ampli-
fiers (CLP1 and CLP2) provides an inherent soft-start of
the output voltage. It includes (R14 and C10) in parallel
with C11 at CLP1 and (R15 and C12) in parallel with
C13 at CLP2 (see Figure 6). The voltage at the current-
error amplifier output limits the maximum current avail-
able to charge the output capacitors. The capacitor at
CLP_ in conjunction with the finite output-drive current
of the current-error amplifier yields a finite rise time for
the output current and thus the output voltage.
Setting the Switching Frequency (fSW)
An internal oscillator generates the 180o out-of-phase
clock signals required for both PWM modulators. The
oscillator also generates the 2VP-P voltage ramps nec-
essary for the PWM comparators. The oscillator fre-
quency can be set from 200kHz to 2MHz by an external
resistor (RT) connected from RT/CLKIN to AGND (see
Figure 6). The equation below shows the relationship
between RT and the switching frequency:
fOSC
=
2.5 × 1010
RRT
Hz
where RRT is in ohms and fSW(PER PHASE) = fOSC/2.
Use RT/CLKIN as a clock input to synchronize the
MAX5066 to an external frequency (fRT/CLKIN). Applying
an external clock to RT/CLKIN allows each PWM section
to work at a frequency equal to fRT/CLKIN/2. An internal
comparator with a 1.6V threshold detects fRT/CLKIN. If
fRT/CLKIN is present, internal logic switches from the
internal oscillator clock, to the clock present at
RT/CLKIN.
______________________________________________________________________________________ 11
11 Page | ||
| Páginas | Total 22 Páginas | |
| PDF Descargar | [ Datasheet MAX5066.PDF ] | |
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