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PDF ISL9113A Data sheet ( Hoja de datos )
| Número de pieza | ISL9113A | |
| Descripción | Synchronous Boost Converter | |
| Fabricantes | Intersil | |
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DATASHEET
Low Input Voltage and High Efficiency, Synchronous
Boost Converter with 1.3A Switch
ISL9113A
The ISL9113A provides a power supply solution for devices
powered by three-cell alkaline, NiCd, NiMH, or one-cell
Li-Ion/Li-Polymer batteries. It offers either a fixed 5V or an
adjustable output option for USB-OTG or portable HDMI
applications. The device is guaranteed to supply 500mA from
a 3V input and 5V output, and has a typical 1.3A peak current
limit. High 1.8MHz switching frequency allows for the use of
tiny, low-profile inductors, and ceramic capacitors to minimize
the size of the overall solution.
The ISL9113A is an internally compensated, fully integrated
synchronous converter optimized for efficiency with minimal
external components. At light load, the device enters Skip
mode and consumes only 20µA of quiescent current, resulting
in higher efficiency at light loads and maximum battery life.
The device is available in an 8 Ld DFN package.
Related Literature
• For a full list of related documents, visit our website
- ISL9113A product page
Features
• Up to 95% efficiency at typical operating conditions
• Input voltage range: 0.8V to 4.7V
• Output current: Up to 500mA (VBAT = 3.0V, VOUT = 5.0V)
• Low quiescent current: 20μA (typical)
• Logic control shutdown (IQ < 1µA)
• 1.2V EN high logic
• Output disconnect during shutdown
• Skip mode under light-load condition
• Undervoltage lockout
• Fault protection: OVP, OTP, short-circuit
• 8 Ld 2mmx2mm DFN Package
Applications
• Products including portable HDMI and USB-OTG
• Smartphones
• Tablet and mobile internet devices
2.2µH
VBAT =
0.8 TO 4.7V
4.7µF
8
SW
7
VBAT
5
EN
2
VOUT
FB 4
GND 1
VOUT =
5.0V/500mA
R1
523k
4.7µF
R2
100k
FIGURE 1. TYPICAL APPLICATION
100 VBAT = 4.2V
95 VBAT = 3.6V
90 VBAT = 3.0V
85
80
75
70
VBAT = 1.2V
65
60
55
50
0.0001
0.001
0.01
LOAD CURRENT (A)
FIGURE 2. EFFICIENCY
VBAT = 2.3V
VOUT = 5.0V
0.1 1
January 4, 2017
FN8620.1
1
CAUTION: These devices are sensitive to electrostatic discharge; follow proper IC Handling Procedures.
1-888-INTERSIL or 1-888-468-3774 | Copyright Intersil Americas LLC 2013, 2017. All Rights Reserved
Intersil (and design) is a trademark owned by Intersil Corporation or one of its subsidiaries.
All other trademarks mentioned are the property of their respective owners.
1 page  
ISL9113A
Detailed Description
Current Mode PWM Operation
The control scheme of the device is based on the peak current
mode control and the control loop is compensated internally. The
peak current of the N-channel MOSFET switch is sensed to limit
the maximum current flowing through the switch and the
inductor. The typical current limit is set to 1.3A.
The control circuit includes a ramp generator, slope
compensator, error amplifier, and a PWM comparator (see
“Block Diagram” on page 2). The ramp signal is derived from the
inductor current. This ramp signal is then compared to the error
amplifier output to generate the PWM gating signals for driving
both N-channel and P-channel MOSFETs. The PWM operation is
initialized by the clock from the internal oscillator (typical
1.8MHz). The N-channel MOSFET is turned ON at the beginning of
a PWM cycle, the P-channel MOSFET remains OFF, and the
current starts ramping up. When the sum of the ramp and the
slope compensator output reaches the error amplifier output
voltage, the PWM comparator outputs a signal to turn OFF the
N-channel MOSFET. Here, both MOSFETs remain OFF during the
dead-time interval. Next, the P-channel MOSFET is turned ON and
remains ON until the end of this PWM cycle. During this time, the
inductor current ramps down until the next clock. At this point,
following a short dead time, the N-channel MOSFET is again
turned ON, repeating as previously described.
Skip Mode Operation
The boost converter is capable of operating in two different
modes. When the inductor current is sensed to cross zero for
eight consecutive times, the converter enters Skip mode. In Skip
mode, each pulse cycle is still synchronized by the PWM clock.
The N-channel MOSFET is turned ON at the rising edge of the
clock and turned OFF when the inductor peak current reaches
typically 25% of the current limit. Then, the P-channel MOSFET is
turned ON, and it stays ON until its current goes to zero.
Subsequently, both N-channel and P-channel MOSFETs are
turned OFF until the next clock cycle starts, at which time the
N-channel MOSFET is turned ON again. When VOUT is 1.5% higher
than the nominal output voltage, the N-channel MOSFET is
immediately turned OFF, and the P-channel MOSFET is turned ON
until the inductor current goes to zero. The N-channel MOSFET
resumes operation when VFB falls back to its nominal value,
repeating the previous operation. The converter returns to
1.8MHz PWM mode operation when VFB drops 1.5% below its
nominal voltage.
Given the Skip mode algorithm incorporated in the ISL9113A,
the average value of the output voltage is approximately 0.75%
higher than the nominal output voltage under PWM operation.
This positive offset improves the load transient response when
switching from Skip mode to PWM mode operation. The ripple on
the output voltage is typically 1.5%*VOUT (nominal) when input
voltage is sufficiently lower than output voltage, and it increases
as the input voltage approaches the output voltage.
Synchronous Rectifier
The ISL9113A integrates one N-channel MOSFET and one
P-channel MOSFET to realize a synchronous boost converter.
Because the commonly used discrete Schottky rectifier is
replaced with the low rDS(ON) P-channel MOSFET, the power
conversion efficiency reaches a value above 90%. Since a typical
step-up converter has a conduction path from the input to the
output via the body diode of the P-channel MOSFET, a special
circuit (see “Block Diagram” on page 2) is used to reverse the
polarity of the P-channel body diode when the device is shut
down. Thus, this configuration completely disconnects the load
from the input during shutdown of the converter. The benefit of
this feature is that the battery will not be completely depleted
during shutdown of the converter. No additional components are
needed to disconnect the battery from the output of the
converter.
Soft-Start
The soft start-up duration is the time between the device being
enabled and VOUT rising to within 3% of target voltage. When the
device is enabled, the start-up cycle starts with a linear phase.
During the linear phase, the rectifying switch is turned ON in a
current limited configuration, delivering about 350mA, until the
output capacitor is charged to approximately 90% of the input
voltage. At this point, PWM operation begins in Boost mode. If
the output voltage is below 2.3V, PWM switching is done at a
fixed duty-cycle of 75% until the output voltage reaches 2.3V.
When the output voltage exceeds 2.3V, the closed-loop current
mode PWM loop overrides the duty cycle until the output voltage
is regulated. Peak inductor current is ramped to the final value
(typically 1.3A) during the soft-start period to limit inrush current
from the input source. Fault monitoring begins approximately
2ms after the device is enabled.
Over-Temperature Protection (OTP)
The device offers over-temperature protection. A temperature
sensor circuit is integrated and monitors the internal IC
temperature. Once the temperature exceeds the preset threshold
(typically +150°C), the IC shuts down immediately. The OTP has
a typical hysteresis of +25°C. When the device temperature
decreases by this, the device starts operating.
Printed Circuit Board Layout
Recommendations
The ISL9113A is a high-frequency, switching boost converter.
Accordingly, the converter has fast voltage change and high
switching current that may cause EMI and stability issues if the
layout is not done properly. Therefore, careful layout is critical to
minimize the trace inductance and reduce the area of the power
loop.
Power components, such as input capacitor, inductor, and output
capacitor, should be placed close to the device. Board traces that
carry high switching current should be routed wide and short. A
solid power ground plane is important for EMI suppression.
The switching node (SW pin) of the converter and the traces
connected to this pin are very noisy. Noise sensitive traces, such
as the FB trace, should be kept away from SW node. The voltage
divider should be placed close to the FB pin to prevent noise
pickup. Figure 4 on page 6 shows the recommended PCB layout.
In the 8 Ld DFN package, the heat generated in the device is
mainly dissipated through the thermal pad. Maximizing the
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FN8620.1
January 4, 2017
5 Page | ||
| Páginas | Total 10 Páginas | |
| PDF Descargar | [ Datasheet ISL9113A.PDF ] | |
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