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ISL8105A の電気的特性と機能

ISL8105AのメーカーはIntersil Corporationです、この部品の機能は「Single-Phase Synchronous Buck Converter PWM」です。


製品の詳細 ( Datasheet PDF )

部品番号 ISL8105A
部品説明 Single-Phase Synchronous Buck Converter PWM
メーカ Intersil Corporation
ロゴ Intersil Corporation ロゴ 




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ISL8105A Datasheet, ISL8105A PDF,ピン配置, 機能
®
Data Sheet
ISL8105, ISL8105A
December 6, 2006
FN6306.3
+5V or +12V Single-Phase Synchronous
Buck Converter PWM Controller with
Integrated MOSFET Gate Drivers
The ISL8105 is a simple single-phase PWM controller for a
synchronous buck converter. It operates from +5V or +12V bias
supply voltage. With integrated linear regulator, boot diode, and
N-channel MOSFET gate drivers, the ISL8105 reduces
external component count and board space requirements.
These make the IC suitable for a wide range of applications.
Utilizing voltage-mode control, the output voltage can be
precisely regulated to as low as 0.6V. The 0.6V internal
reference features a maximum tolerance of ±1.0% over the
commercial temperature range, and ±1.5% over the
industrial temperature range. Two fixed oscillator frequency
versions are available; 300kHz (ISL8105 for high efficiency
applications) and 600kHz (ISL8105A for fast transient
applications).
The ISL8105 features the capability of safe start-up with
pre-biased load. It also provides overcurrent protection by
monitoring the on resistance of the bottom-side MOSFET to
inhibit PWM operation appropriately. During start-up interval,
the resistor connected to BGATE/BSOC pin is employed to
program overcurrent protection condition. This approach
simplifies the implementation and does not deteriorate
converter efficiency.
Pinouts
ISL8105
(10 LD 3X3 DFN)
TOP VIEW
BOOT 1
TGATE 2
N/C 3
GND 4
BGATE/BSOC 5
GND
10 LX
9 COMP/EN
8 FB
7 N/C
6 VBIAS
ISL8105
(8 LD SOIC)
TOP VIEW
BOOT 1
TGATE 2
GND 3
BGATE/BSOC 4
8 LX
7 COMP/EN
6 FB
5 VBIAS
Features
• Operates from +5V or +12V Bias Supply Voltage
- 1.0V to 12V Input Voltage Range (up to 20V possible
with restrictions; see Input Voltage Considerations)
- 0.6V to VIN Output Voltage Range
• 0.6V Internal Reference Voltage
- ±1.0% Tolerance Over the Commercial Temperature
Range (0°C to +70°C)
- ±1.5% Tolerance Over the Industrial Temperature
Range (-40°C to +85°C).
• Integrated MOSFET Gate Drivers that Operate from VBias
(+5V to +12V)
- Bootstrapped High-side Gate Driver with Integrated
Boot Diode
- Drives N-Channel MOSFETs
• Simple Voltage-Mode PWM Control
• Fast Transient Response
- High-Bandwidth Error Amplifier
- Full 0% to 100% Duty Cycle
• Fixed Operating Frequency
- 300kHz for ISL8105
- 600kHz for ISL8105A
• Fixed Internal Soft-Start with Pre-biased Load Capability
• Lossless, Programmable Overcurrent Protection
- Uses Bottom-side MOSFET’s rDS(ON)
• Enable/Disable Function Using COMP/EN Pin
• Output Current Sourcing and Sinking Currents
• Pb-Free Plus Anneal Available (RoHS Compliant)
Applications
• 5V or 12V DC/DC Regulators
• Industrial Power Systems
• Telecom and Datacom Applications
• Test and Measurement Instruments
• Distributed DC/DC Power Architecture
• Point of Load Modules
1 CAUTION: These devices are sensitive to electrostatic discharge; follow proper IC Handling Procedures.
1-888-INTERSIL or 1-888-468-3774 | Intersil (and design) is a registered trademark of Intersil Americas Inc.
Copyright Intersil Americas Inc. 2005-2006. All Rights Reserved
All other trademarks mentioned are the property of their respective owners.

1 Page





ISL8105A pdf, ピン配列
Block Diagram
FB
COMP/EN
VBIAS
SAMPLE
AND
HOLD
+
-
OC
COMPARATOR
POR AND
SOFT-START
INTERNAL
REGULATOR
5V INT.
DBOOT
21.5μA
TO
BGATE/BSOC
5V INT.
20μA
0.6V
+
-
ERROR
AMP
0.4V
+
-
DIS
PWM
COMPARATOR
+
-
OSCILLATOR
20kΩ
INHIBIT
PWM
GATE
CONTROL
LOGIC
DIS
VBias
FIXED 300kHZ OR 600KHz
BOOT
TGATE
LX
BGATE/BSOC
GND


3Pages


ISL8105A 電子部品, 半導体
ISL8105, ISL8105A
Functional Description
Initialization (POR and OCP Sampling)
Figure 1 shows a start-up waveform of ISL8105. The
Power-On-Reset (POR) function continually monitors the
bias voltage at the VBIAS pin. Once the rising POR
threshold is exceeded 4V (VPOR nominal), the POR function
initiates the Overcurrent Protection (OCP) sample and hold
operation (while COMP/EN is ~1V). When the sampling is
complete, VOUT begins the soft-start ramp.
VBIAS
~4V POR
VOUT
VCOMP/EN
FIGURE 1. POR AND SOFT-START OPERATION
If the COMP/EN pin is held low during power-up, the
initialization will be delayed until the COMP/EN is released
and its voltage rises above the VDISABLE trip point.
Figure 2 shows a typical power-up sequence in more detail.
The initialization starts at T0, when either VBias rises above
VPOR, or the COMP/EN pin is released (after POR). The
COMP/EN will be pulled up by an internal 20µA current
source, but the timing will not begin until the COMP/EN
exceeds the VDISABLE trip point (at T1). The external
capacitance of the disabling device, as well as the
compensation capacitors, will determine how quickly the
20µA current source will charge the COMP/EN pin. With
BGATE
STARTS
SWITCHING
COMP/EN
BGATE/BSOC
3.4ms
T0 T1
3.4ms
0 - 3.4ms
T2 T3 T4
VOUT
T5
FIGURE 2. BGATE/BSOC AND SOFT-START OPERATION
typical values, it should add a small delay compared to the
soft-start times. The COMP/EN will continue to ramp to ~1V.
From T1, there is a nominal 6.8ms delay, which allows the
VBIAS pin to exceed 6.5V (if rising up towards 12V), so that
the internal bias regulator can turn on cleanly. At the same
time, the BGATE/BSOC pin is initialized by disabling the
BGATE driver and drawing BSOC (nominal 21.5µA) through
RBSOC. This sets up a voltage that will represent the BSOC
trip point. At T2, there is a variable time period for the OCP
sample and hold operation (0ms to 3.4ms nominal; the
longer time occurs with the higher overcurrent setting). The
sample and hold uses a digital counter and DAC to save the
voltage, so the stored value does not degrade, for as long as
the VBias is above VPOR. See “Overcurrent Protection
(OCP)” on page 7 for more details on the equations and
variables. Upon the completion of sample and hold at T3, the
soft-start operation is initiated, and the output voltage ramps
up between T4 and T5.
Soft-Start and Pre-Biased Outputs
Functionally, the soft-start internally ramps the reference on
the non-inverting terminal of the error amp from zero to 0.6V
in a nominal 6.8ms. The output voltage will thus follow the
ramp, from zero to final value, in the same 6.8ms (the actual
ramp seen on the VOUT will be less than the nominal time),
due to some initialization timing, between T3 and T4).
The ramp is created digitally, so there will be 64 small
discrete steps. There is no simple way to change this ramp
rate externally, and it is the same for either frequency
version of the IC (300kHz or 600kHz).
After an initialization period (T3 to T4), the error amplifier
(COMP/EN pin) is enabled, and begins to regulate the
converter's output voltage during soft-start. The oscillator's
triangular waveform is compared to the ramping error
amplifier voltage. This generates LX pulses of increasing
width that charge the output capacitors. When the internally
generated soft-start voltage exceeds the reference voltage
(0.6V), the soft-start is complete and the output should be in
regulation at the expected voltage. This method provides a
rapid and controlled output voltage rise; there is no large
inrush current charging the output capacitors. The entire
start-up sequence from POR typically takes up to 17ms; up
to 10.2ms for the delay and OCP sample and 6.8ms for the
soft-start ramp.
Figure 3 shows the normal curve in blue; initialization begins
at T0, and the output ramps between T1 and T2. If the output
is pre-biased to a voltage less than the expected value, as
shown by the red curve, the ISL8105 will detect that
condition. Neither MOSFET will turn on until the soft-start
ramp voltage exceeds the output; VOUT starts seamlessly
ramping from there. If the output is pre-biased to a voltage
above the expected value, as in the gray curve, neither
MOSFET will turn on until the end of the soft-start, at which
time it will pull the output voltage down to the final value. Any
6 FN6306.3
December 6, 2006

6 Page



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部品番号部品説明メーカ
ISL8105

Single-Phase Synchronous Buck Converter PWM

Intersil Corporation
Intersil Corporation
ISL8105A

Single-Phase Synchronous Buck Converter PWM

Intersil Corporation
Intersil Corporation
ISL8105B

Single-Phase Synchronous Buck Converter PWM

Intersil Corporation
Intersil Corporation


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