|
|
PDF MAX1709 Data sheet ( Hoja de datos )
| Número de pieza | MAX1709 | |
| Descripción | 4A / Low-Noise / High-Frequency / Step-Up DC-DC Converter | |
| Fabricantes | Maxim Integrated | |
| Logotipo |  |
|
Hay una vista previa y un enlace de descarga de MAX1709 (archivo pdf) en la parte inferior de esta página. Total 12 Páginas | ||
|
No Preview Available !
19-1724; Rev 0; 5/00
4A, Low-Noise, High-Frequency,
Step-Up DC-DC Converter
General Description
The MAX1709 sets a new standard of space savings for
high-power, step-up DC-DC conversion. It delivers up
to 20W at a fixed (3.3V or 5V) or adjustable (2.5V to
5.5V) output, using an on-chip power MOSFET from a
+0.7V to +5V supply.
Fixed-frequency PWM operation ensures that the
switching noise spectrum is constrained to the 600kHz
fundamental and its harmonics, allowing easy postfilter-
ing for noise reduction. External clock synchronization
capability allows for even tighter noise spectrum con-
trol. Quiescent power consumption is less than 1mW to
extend operating time in battery-powered systems.
Two control inputs (ONA, ONB) allow simple push-on,
push-off control through a single momentary pushbut-
ton switch, as well as conventional on/off logic control.
The MAX1709 also features programmable soft-start
and current limit for design flexibility and optimum per-
formance with batteries. The maximum RMS switch cur-
rent rating is 10A. For a device with a lower current
rating, smaller size, and lower cost, refer to the
MAX1708 data sheet.
________________________Applications
Routers, Servers, Workstations, Card Racks
Local 2.5V to 3.3V or 5V Conversion
Local 3.3V to 5V Conversion
3.6V or 5V RF PAs in Communications Handsets
Features
o On-Chip 10A Power MOSFET
o 5V, 4A Output from a 3.3V Input
o Fixed 3.3V or 5V Output Voltage or
Adjustable (2.5V to 5.5V)
o Input Voltage Range Down to 0.7V
o Low Power Consumption
1mW Quiescent Power
1µA Current in Shutdown Mode
o Low-Noise, Constant Frequency Operation
(600kHz)
o Synchronizable Switching Frequency
(350kHz to 1000kHz)
PART
MAX1709ESE
Ordering Information
TEMP. RANGE
-40°C to +85°C
PIN-PACKAGE
16 Narrow SO
Typical Operating Circuit
INPUT
1V TO 5V
1µH
OFF ON
SYNC
OR
INTERNAL
ONA LX
MAX1709
CLK
SS/LIM
GND
REF OUT
OUTPUT
3.3V, 5V,
OR ADJ
UP TO 4A
Pin Configuration
TOP VIEW
ONA 1
LX 2
LX 3
LX 4
GND 5
SS/LIM 6
REF 7
GND 8
MAX1709
16 ONB
15 CLK
14 3.3/5
13 PGND
12 PGND
11 PGND
10 FB
9 OUT
NARROW SO
________________________________________________________________ Maxim Integrated Products 1
For free samples and the latest literature, visit www.maxim-ic.com or phone 1-800-998-8800.
For small orders, phone 1-800-835-8769.
1 page  
4A, Low-Noise, High-Frequency,
Step-Up DC-DC Converter
(TA = +25°C, unless otherwise noted.)
EFFICIENCY vs.
OUTPUT CURRENT (VOUT = 3.3V)
100
90 VIN = 2.5V
80
70 VIN = 1.2V
60
50
40
30
20
10
0
0.001
0.01 0.1
1
OUTPUT CURRENT (A)
10
Typical Operating Characteristics
EFFICIENCY vs.
OUTPUT CURRENT (VOUT = 5V)
100
90
80 VIN = 3.3V
70 VIN = 2.5V
60
50
40
30
20
10
0
0.001
0.01 0.1
1
OUTPUT CURRENT (A)
10
EFFICIENCY vs. SWITCHING FREQUENCY
(VIN = 3.3V, VOUT = 5V, IOUT = 2A)
86.0
85.5
85.0
84.5
84.0
83.5
83.0
0.4
0.5 0.6 0.7 0.8 0.9
OPERATING FREQUENCY (MHz)
1.0
LOAD REGULATION
(VIN = 3.3V, VOUT = 5V)
2
1
0
-1
-2
0
1234
OUTPUT CURRENT (A)
5
STARTUP VOLTAGE
vs. LOAD CURRENT
2.8
2.6
2.4
2.2
2.0
1.8
1.6 VOUT = 3.3V
1.4
1.2 TA = -40°C
1.0
0.8 TA = +25°C
0.6 TA = +85°C
0.001
0.01
0.1
VOUT = 5V
1 10
LOAD CURRENT (A)
0.8
0.6
0.4
0.2
0
-0.2
-0.4
-0.6
-0.8
2.0
LINE REGULATION
(VOUT = 5V, IOUT = 1A)
2.5 3.0 3.5
INPUT VOLTAGE (V)
4.0
1.0
0.5
0
-0.5
-1.0
-1.5
-2.0
-40
SWITCHING FREQUENCY
vs. TEMPERATURE
VOUT = 3.3V
-15 10 35 60
TEMPERATURE (°C)
85
NO-LOAD INPUT CURRENT
vs. INPUT VOLTAGE
1000
INPUT VOLTAGE
INCREASING
100
INPUT VOLTAGE
DECREASING
10
VOUT = 5V
1
0.1
0
VOUT = 3.3V
0.5 1.0 1.5 2.0 2.5 3.0 3.5
INPUT VOLTAGE (V)
30
25
20
15
10
5
0
-5
-10
0.1
NOISE vs. FREQUENCY
1
FREQUENCY (MHz)
10
_______________________________________________________________________________________ 5
5 Page 
4A, Low-Noise, High-Frequency,
Step-Up DC-DC Converter
ON/OFF
270k
MAX1709
ONB
ONA
µC
VDD
I/O
I/O
0.1µF
270k
capacitor to GND and a 2Ω series resistor (R2, as
shown in Figure 1).
MAX1709 IC Power Dissipation
The major components of MAX1709 dissipated power
are switch conductance loss (PSW), capacitive loss
(PCAP), and switch transition loss (PTRAN). Throughout
the formulas, numerical examples are provided in {},
corresponding to the following condition:
{VIN = 3.3V, VOUT = 5V, VD = 0.5V, IOUT = 4A}
An important parameter to compute the power dissipat-
ed in the MAX1709 is the approximate peak switch cur-
rent (ISW):
Figure 5. Momentary Pushbutton On-Off Switch
ILIM = minimum value of switch current limit from Elec-
trical Characteristics or set by RSET/LIM.
Diode Selection (D1)
The MAX1709’s high switching frequency demands a
high-speed rectifier. Schottky diodes, such as the
MBRD1035CTL or STPS8L30B (Table 3), are recom-
mended. The diode’s current rating must exceed the
maximum load current, and its breakdown voltage must
exceed VOUT. The diode must be placed within 10mm
of the LX switching node and the output filter capacitor.
The diode also must be able to dissipate the power cal-
culated by the following equation:
PDIODE = IOUT ✕ VD
where IOUT is the average load current and VD is the
diode forward voltage at the peak switch current.
Capacitor Selection
Input Bypass Capacitors (C1, C2)
Two 150µF, low-ESR tantalum input capacitors will
reduce peak currents and reflected noise due to induc-
tor current ripple. Lower ESR allows for lower input rip-
ple current, but combined ESR values up to 50mΩ are
acceptable. Smaller ceramic capacitors may also be
used for light loads or in applications that can tolerate
higher input current ripple.
Output Filter Capacitors (C6, C7)
The output filter capacitor ESR must be kept under
15mΩ for stable operation. Two parallel 150µF polymer
capacitors (Panasonic EEFUE0J151R) typically exhibit
5mΩ of ESR. This translates to approximately 35mV of
output ripple at 7A switch current. Bypass the
MAX1709 IC supply input (OUT) with a 0.1µF ceramic
ISW
=
IOUT
D'
D' =
VIN
VOUT + VD
{6.67A}
{0.6}
PD (MAX1709) = PSW + PCAP + PTRAN
PSW = (1 - D') ISW2 ✕ RSW
{0.83W}
{0.59W}
where:
RSW = switch resistance {33mΩ}
PCAP = (CDIO + CDSW + CGSW) (VOUT + VD)2f {0.09W}
CDIO = catch-diode capacitance {1000pF}
CDSW = switch drain capacitance {2500pF}
CGSW = switch gate capacitance {1500pF}
f = switching frequency {600kHz}
PTRAN = (VOUT + VD) ISW ✕ tSW ✕ f / 3
{0.15W}
where tSW = is switch turn-on or turn-off time {20ns}.
Applications Information
Using a Momentary On/Off Switch
A momentary pushbutton switch can be used to turn
the MAX1709 on and off. As shown in Figure 5, when
ONA is pulled low and ONB is pulled high, the part is
off. When the momentary switch is pressed, ONB is
pulled low and the regulator turns on. The switch
should be on long enough for the microcontroller to exit
reset. The controller issues a logic high to ONA, which
guarantees that the part will stay on regardless of the
subsequent switch state. To turn the regulator off,
press the switch long enough for the controller to read
the switch status and pull ONA low. When the switch is
released, ONB pulls high and the regulator turns off.
Layout Considerations
Due to high inductor current levels and fast switching
waveforms, proper PC board layout is essential. Protect
sensitive analog grounds by using a star ground config-
______________________________________________________________________________________ 11
11 Page | ||
| Páginas | Total 12 Páginas | |
| PDF Descargar | [ Datasheet MAX1709.PDF ] | |
Hoja de datos destacado
| Número de pieza | Descripción | Fabricantes |
| MAX170 | Serial Output 5.6us 12-Bit A/D Converter | Maxim Integrated |
| MAX1700 | Step-Up DC-DC Converters | Maxim Integrated |
| MAX17000 | Complete DDR2 and DDR3 Memory Power-Management Solution | Maxim Integrated |
| MAX17000A | Complete DDR2 and DDR3 Memory Power-Management Solution |  Maxim Integrated Products |
| 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 |