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PDF MAX77596 Data sheet ( Hoja de datos )
| Número de pieza | MAX77596 | |
| Descripción | Buck Converter | |
| Fabricantes | Maxim Integrated | |
| Logotipo |  |
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Hay una vista previa y un enlace de descarga de MAX77596 (archivo pdf) en la parte inferior de esta página. Total 15 Páginas | ||
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MAX77596
EVALUATION KIT AVAILABLE
24V, 300mA, Buck Converter with 1.1µA IQ
General Description
The MAX77596 is a small, synchronous buck converter
with integrated switches. The device is designed to
deliver up to 300mA with input voltages from 3.5V to
24V, while using only 1.1µA quiescent current at no load
(fixed-output version). Voltage quality can be monitored
by observing the RESET signal. The device can operate
near dropout by running at 98% duty cycle, making it ideal
for battery-powered applications.
The device offers a fixed 3.3V output version, as well as
an adjustable version. The adjustable version allows the
user to program the output voltage between 1V and 10V
by using a resistor-divider. Frequency is fixed at 1.7MHz,
which allows for small external components and reduced
output ripple. The device offers both forced-PWM and
skip modes of operation, with ultra-low quiescent current
of 1.1µA in skip mode.
The MAX77596 is available in a small (2mm x 2.5mm)
10-pin TDFN package and operates across the -40°C to
+85°C temperature range.
Applications
● Portable Devices Powered from 2s, 3s,
or 4s Li+ Batteries
● USB Type-C Devices
● Point-of-Load Applications
Benefits and Features
● Flexible Power for Systems That Require a Wide
Input Voltage Range
• VIN Range: 3.5V to 24V
• Up to 300mA Output Current
• Fixed 3.3V or Programmable 1V to 10V Output
Voltage
• 98% (Max) Duty Cycle Operation with Low
Dropout
• Operates from 5V, 12V, or 20V USB Type-C Input
Power
• Operates from 2S, 3S, or 4S Li-Ion Battery
● Minimizes Power Consumption and Extends Battery
Life
• 1.1µA Quiescent Current (3.3V Fixed Output
Voltage)
• 86% Peak Efficiency at 12VIN, 3.3 VOUT
● Minimizes Solution Size
• 1.7MHz Operating Frequency
• Small 2.0mm x 2.5mm x 0.75mm 10-Pin TDFN
Package
● Robust Solution
• Short-Circuit, Thermal Protections
• 6.6ms Internal Soft-Start Minimizes Inrush Current
• Current-Mode Control Architecture
• Up to 42V Input Voltage Tolerance
19-7733; Rev 0; 10/15
1 page  
MAX77596
24V, 300mA, Buck Converter with 1.1µA IQ
Typical Operating Characteristics (continued)
(VSUP = VEN = 12V, TA = +25°C, unless otherwise noted.)
LOAD REGULATION
3.3V FIXED-OUTPUT
3.34 toc08
VSUP = 12V
3.32
SKIP
3.30
3.28 FPWM
3.26
3.34
3.32
3.30
3.28
3.26
LOAD REGULATION
3.3V FIXED-OUTPUT
toc09
VSUP = 20V
FPWM
SKIP
VEN
5V/div
ISUP
0.1A/div
VBIAS
5V/div
START-UP WAVEFORM
3.3V ADJUSTABLE-OUTPUT
(SKIP, 0mA LOAD)
24V
toc10
3.9V
3.3V
3.24
3.22
0
3.24
50 100 150 200 250 300
OUTPUT CURRENT (mA)
3.22
0
3.34
3.32
3.30
3.28
3.26
3.24
3.22
3.20
3.18
0
LINE REGULATION
3.3V FIXED-OUTPUT
IOUT = 100mA
toc11
IOUT = 300mA
5 10 15 20
SUPPLY VOLTAGE (V)
25
50 100 150 200 250 300
OUTPUT CURRENT (mA)
VOUT
1V/div
0V
1ms/div
LOAD TRANSIENT RESPONSE
3.3V FIXED-OUTPUT (SKIP)
VSUP = 12V
toc12
IOUT
VOUT
200mA/div
100mV/div
(3.3V offset)
100µs/div
LOAD TRANSIENT RESPONSE
3.3V FIXED-OUTPUT (FPWM)
toc13
VSUP =V1S2UVP = 12V
IOUT 200mA/div
VOUT
100mV/div
(3.3V offset)
LOAD TRANSIENT RESPONSE
3.3V ADJUSTABLE-OUTPUT (SKIP)
toc14
VSUP =V1S2UVP = 12V
IOUT 200mA/div
VOUT
100mV/div
(3.3V offset)
100µs/div
www.maximintegrated.com
100µs/div
Maxim Integrated │ 5
5 Page 
MAX77596
24V, 300mA, Buck Converter with 1.1µA IQ
Input Capacitor
The input filter capacitor reduces peak currents drawn
from the power source and reduces noise and voltage
ripple on the input caused by the circuit’s switching.
The input capacitor RMS current requirement (IRMS) is
defined by the following equation:
IRMS = ILOAD(MAX)
VOUT × (VSUP − VOUT )
VSUP
IRMS has a maximum value when the input voltage
equals twice the output voltage (VSUP = 2VOUT), so
IRMS(MAX) = ILOAD(MAX)/2.
Choose an input capacitor that exhibits less than +10°C
self-heating temperature rise at the RMS input current for
optimal long-term reliability.
The input voltage ripple is composed of ΔVQ (caused
by the capacitor discharge) and ΔVESR (caused by the
ESR of the capacitor). Use low-ESR ceramic capacitors
with high ripple current capability at the input. Assume
the contribution from the ESR and capacitor discharge
equal to 50%. Calculate the input capacitance and ESR
required for a specified input voltage ripple using the
following equations:
ESRIN
=
∆VESR
IOUT
+
∆IL
2
where:
∆IL
=( VSUP − VOUT ) × VOUT
VSUP × fSW × L
and:
=CIN
I=OUT × D(1− D) and D
∆VQ × fSW
VOUT
VSUP
where IOUT is the maximum output current and D is the
duty cycle.
Output Capacitor
The output filter capacitor must have low enough ESR to
meet output ripple and load transient requirements. The
output capacitance must be high enough to absorb the
inductor energy while transitioning from full-load to no-
load conditions. When using high-capacitance, low-ESR
capacitors, the filter capacitor’s ESR dominates the out-
put voltage ripple. Therefore, the size of the output capac-
itor depends on the maximum ESR required to meet the
output voltage ripple (VRIPPLE(P-P)) specifications:
VRIPPLE(P−P) =ESR × ILOAD(MAX) × LIR
The actual capacitance value required relates to the
physical size needed to achieve low ESR, as well as to
the chemistry of the capacitor technology. Therefore, the
capacitor is usually selected by ESR and voltage rating
rather than by capacitance value.
When using low-capacity filter capacitors, such as ceram-
ic capacitors, size is usually determined by the capacity
needed to prevent voltage droop and voltage rise from
causing problems during load transients. Generally, once
enough capacitance is added to meet the overshoot
requirement, undershoot at the rising-load edge is no
longer a problem.
PCB Layout Guidelines
Careful PCB layout is critical to achieve low-switching
power losses and clean, stable operation. Use a multi-
layer board whenever possible for better noise immunity
and power dissipation. Follow these guidelines for good
PCB layout:
1) The input capacitor (4.7µF, see Figures 3 and 4) should
be placed immediately next to the SUP pin of the
device. Since the device operates at 1.7MHz switch-
ing frequency, this placement is critical for effective
decoupling of high-frequency noise from the SUP pin.
2) Solder the exposed pad to a large copper plane area
under the device. To effectively use this copper area as
heat exchanger between the PCB and ambient, expose
the copper area on the top and bottom sides. Add a
few small vias or one large via on the copper pad for
efficient heat transfer. Connect the exposed pad to
PGND, ideally at the return terminal of the output
capacitor.
3) Isolate the power components and high-current path
from the sensitive analog circuitry. Doing so is essential
to prevent any noise coupling into the analog signals.
4) Keep the high-current paths short, especially at the
ground terminals. This practice is essential for stable,
jitter-free operation.
5) Connect PGND and AGND together at the return
terminal of the output capacitor. Do not connect them
anywhere else.
6) Keep the power traces and load connections short.
This practice is essential for high efficiency.
7) Place the BIAS capacitor ground next to the AGND pin
and connect with a short and wide trace.
www.maximintegrated.com
Maxim Integrated │ 11
11 Page | ||
| Páginas | Total 15 Páginas | |
| PDF Descargar | [ Datasheet MAX77596.PDF ] | |
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