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PDF ISL78113A Data sheet ( Hoja de datos )
| Número de pieza | ISL78113A | |
| Descripción | Low Input Voltage and High Efficiency Synchronous Boost Converter | |
| Fabricantes | Intersil Corporation | |
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Low Input Voltage and High Efficiency Synchronous
Boost Converter with 1.3A Switch
ISL78113A
The ISL78113A provides a tiny and convenient boost power
supply solution to generate a regulated output up to 500mA
from any sub-5V secondary rail found in an automotive
electrical system, including battery powered applications
(NiCd, NiMH, or one-cell Li-Ion/Li-Polymer). It offers an
adjustable output (3.0V to 5.2V) supporting USB-OTG or HDMI
applications. The device is able to supply 500mA from a 3V
input and 5V output, and has a typical 1.3A peak current limit.
The ISL78113A is a fully integrated, internally compensated,
synchronous converter optimized to maximize efficiency and
reduce the overall solution size and bill of materials. Its high
2MHz switching frequency allows the use of tiny, low-profile
inductors and chip capacitors. It also eliminates potential
interference within the AM radio band and the external EMI
filtering needed for converters switching at lower rates. To
minimize power consumption while off, the device features an
ultra-low current shutdown mode dropping quiescent current
to 50nA typical.
ISL78113A is supplied in an 8 Ld DFN package. The device is
rated to operate over the temperature range of -40°C to
+105°C.
Features
• Output disconnect during shutdown preventing output
precharging and uncontrolled short-circuit current
• Input voltage range: 0.8V to 4.7V
• Output current: Up to 500mA (VBAT = 3V, VOUT = 5V)
•L ogic control shutdown (IQ < 1µA)
• 2MHz switching frequency
• Up to 95% efficiency at typical operating conditions
• Fault protection: OVP, OCP, OTP, UVLO
• 2mmx2mm 8 Ld DFN package
• Qualified for automotive operations
Applications
• Automotive head units and infotainment systems: especially
those including portable HDMI and USB-OTG connectivity
• Automotive camera systems
6.8 µH
VBAT =
0.8V TO 4.7V
10µF
8
SW
7
VBAT
5
EN
VOUT
2
4
FB
1
GND
VOUT =
5.0V/500mA
422
10µF
80.6
ISL78113AARAZ
FIGURE 1. TYPICAL APPLICATION
100
90
80
70
60
50
40
30
20
10
0
0
VBAT = 3.6V
VBAT = 4.2V
VBAT = 2.3V
VBAT = 3.4V
VBAT = 3V
0.1 0. 2 0. 3 0. 4
0.5 0.6
LOAD CURRENT ILOAD (A)
FIGURE 2. EFFICIENCY vs LOAD CURRENT
May 1, 2014
FN8638. 0
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 2014. 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.
http://www.Datasheet4U.com
1 page  
ISL78113A
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 current ramp generator, slope
compensator, error amplifier and a PWM comparator (see the
“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 2MHz).
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.
Synchronous Rectifier
The ISL78113A 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%.
VOUT Isolation
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 the “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 the target voltage. When
the device is enabled, the start-up cycle starts with a linear
operating 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 current limit value (typically 1.3A) during the soft-start
period to limit in-rush current from the input source. Fault
monitoring begins approximately 2ms after the device is
enabled.
To start up with a slow VBAT ramp-up rate is likely to cause the
device to enter hiccup mode. This is a result of the input voltage
dropping due to start-up current, which causes a fault of VOUT out
of regulation, especially at high load and cold temperature.
Check the input ramp-up rate and a faster input slew rate would
help to resolve this.
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.
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5
FN8638.0
May 1, 2014
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ISL78113A
Typical Characteristics
Typical values are at TA = +25°C. (Continued)
VIN = 3.4V, VOUT = 5V, L = 6.8µH, COUT = 10µF, R1 = 422Ω, R2 = 80.6Ω; unless otherwise noted.
100
VBAT = 3.6V
90
80
VBAT = 4.2V
70 VBAT = 3.4V
60 VBAT = 2.3V
VBAT = 3V
50
40
30
20
10 R1 = 121k
R2 = 22.1k
0
0
0.1 0.
2
0.3 0.
4
0.5 0.
6
LOAD CURRENT ILOAD (A)
FIGURE 17. EFFICIENCY vs LOAD CURRENT
Revision History
The revision history provided is for informational purposes only and is believed to be accurate, but not warranted. Please go to web to make sure you
have the latest revision.
DATE
REVISION
CHANGE
May 1, 2014
FN8638.0 Initial Release.
About Intersil
Intersil Corporation is a leading provider of innovative power management and precision analog solutions. The company's products
address some of the largest markets within the industrial and infrastructure, mobile computing and high-end consumer markets.
For the most updated datasheet, application notes, related documentation and related parts, please see the respective product
information page found at www.intersil.com.
You may report errors or suggestions for improving this datasheet by visiting www.intersil.com/ask.
Reliability reports are also available from our website at www.intersil.com/support
For additional products, see www.intersil.com/en/products.html
Intersil Automotive Qualified products are manufactured, assembled and tested utilizing TS16949 quality systems as noted
in the quality certifications found at www.intersil.com/en/support/qualandreliability.html
Intersil products are sold by description only. Intersil Corporation reserves the right to make changes in circuit design, software and/or specifications at any time
without notice. Accordingly, the reader is cautioned to verify that data sheets are current before placing orders. Information furnished by Intersil is believed to be
accurate and reliable. However, no responsibility is assumed by Intersil or its subsidiaries for its use; nor for any infringements of patents or other rights of third
parties which may result from its use.No licenseis granted by implication or otherwise under any patent or patent rights of Intersil or its subsidiaries.
For information regarding Intersil Corporation and its products, see www.intersil.com
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