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參數(shù)資料
| 型號(hào)： | SI9165 |
| 廠商： | Vishay Intertechnology,Inc. |
| 英文描述： | High Frequency 600-mA Synchronous Buck/Boost Converter |
| 中文描述： | 高頻600毫安同步降壓/升壓轉(zhuǎn)換器 |
| 文件頁(yè)數(shù)： | 7/8頁(yè) |
| 文件大?。?/td> | 74K |
| 代理商： | SI9165 |
Si9165
Vishay Siliconix
Document Number: 70845
S-40693—Rev. C, 19-Apr-04
www.vishay.com
7
PWM Mode
With PWM/PSM mode pin in logic high condition, the Si9165
operates in constant frequency (PWM) mode. As the load and
line varies, switching frequency remain constant. The
switching frequency is programmed by the Rosc value as
shown by the Oscillator curve. In the PWM mode, the
synchronous drive is always enabled, even when the output
current reaches 0 A. In continuous current mode, transfer
function of the converter remain constant, providing fast
transient response. If the converter operates in discontinuous
current mode, overall loop gain decreases and transient
response time can be ten times longer than if the converter
remain in continuous current mode. This transient response
time advantage can significantly decrease the hold-up
capacitors needed on the output of dc-dc converter to meet the
transient voltage regulation. Therefore, the PWM/PSM pin is
available to dynamically program the controller.
The maximum duty cycle of the Si9165 can reach 100% in
buck mode. This allows the system designers to extract out
the maximum stored energy from the battery. Once the
controller delivers 100% duty cycle, converter operates like a
saturated linear regulator. At 100% duty cycle, synchronous
rectification is completely turned off. Up to a maximum duty
cycle of 80% at 2-MHz switching frequency, controller
maintains perfect output voltage regulation. If the input voltage
drops below the level where the converter requires greater
than 80% duty cycle, controller will deliver 100% duty cycle.
This instantaneous jump in duty cycle is due to fixed BBM time,
MOSFET delay/rise/fall time, and the internal propagational
delays. In order to maintain regulation, controller might
fluctuate its duty cycle back and forth from 100% to something
less than maximum duty cycle while the converter is operating
in this input voltage range. If the input voltage drops further,
controller will remain on 100%. If the input voltage increases
to a point where it requires less than 80% duty cycle,
synchronous rectification is once again activated.
The maximum duty cycle under boost mode is internally limited
to 75% to prevent inductor saturation. If the converter is turned
on for 100% duty cycle, inductor never gets a chance to
discharge its energy and eventually saturates. In boost mode,
synchronous rectifier is always turned on for minimum or
greater duration as long as the switch has been turned on. The
controller will deliver 0% duty cycle, if the input voltage is
greater than the programmed output voltage. Because of
signal propagation time and MOSFET delay/rise/fall time,
controller will not transition smoothly from minimum
controllable duty cycle to 0% duty cycle. For example,
controller may decrease its duty cycle from 5% to 0% abruptly,
instead of gradual decrease you see from 75% to 5%.
Pulse Skipping Mode
The gate charge losses produced from the Miller capacitance
of MOSFETs are the dominant power dissipation parameter
during light load (i.e. < 10 mA). Therefore, less gate switching
will improve overall converter efficiency. This is exactly why
the Si9165 is designed with pulse skipping mode. If the
PWM/PSM pin is connected to logic low level, converter
operates in pulse skipping modulation (PSM) mode. During
the pulse skipping mode, quiescent current of the controller is
decreased to approximately 200 A, instead of 500 A during
the PWM mode. This is accomplished by turning off most of
internal control circuitry and utilizing a simple constant on-time
control with feedback comparator. The controller is designed
to have a constant on-time and a minimum off-time acting as
the feedback comparator blanking time. If the output voltage
drops below the desired level, the main switch is first turned on
and then off. If the applied on-time is insufficient to provide the
desired voltage, the controller will force another on and off
sequence, until the desired voltage is accomplished. If the
applied on-time forces the output to exceed the desired level,
as typically found in the light load condition, the converter stays
off. The excess energy is delivered to the output slowly, forcing
the converter to skip pulses as needed to maintain regulation.
The on-time and off-time are set internally based on inductor
used (1.5- H Typical), Mode pin selection and maximum load
current. Wide duty cycle range can be achieved in both buck
and boost configurations. In pulse skipping mode,
synchronous rectifier drive is also disabled to further decrease
the gate charge loss, which in turn improves overall converter
efficiency.
Reference
The reference voltage of the Si9165 is set at 1.3 V. The
reference voltage is internally connected to the non-inverting
inputs of the error amplifier. The reference is decoupled with
0.1- F capacitor.
Error Amplifier
The error amplifier gain-bandwidth product and slew rate is
critical parameters which determines the transient response of
converter. The transient response is function of both small and
large signal response. The small signal is the converter closed
loop bandwidth and phase margin while the large signal is
determined by the error amplifier dv/dt and the inductor di/dt
slew rate. Besides the inductance value, error amplifier
determines the converter response time. In order to minimize
the response time, the Si9165 is designed with 2-MHz error
amplifier gain-bandwidth product to generate the widest
converter bandwidth and 3.5 V/ sec slew rate for ultra-fast
large signal response.
Oscillator
The oscillator is designed to operate up to 2-MHz minimal. The
2-MHz operating frequency allows the converter to minimize
the inductor and capacitor size, improving the power density
of the converter. Even with 2-MHz switching frequency,
quiescent current is only 500 A with unique power saving
circuit design. The switching frequency is easily programmed
by attaching a resistor to R
OSC
pin. See oscillator frequency
versus R
OSC
curve to select the proper values for desired
operating frequency. The tolerance on the operating
frequency is
20% with 1% tolerance resistor.
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相關(guān)代理商/技術(shù)參數(shù) |
參數(shù)描述 |
|---|---|
| SI9165_07 | 制造商:VISHAY 制造商全稱:Vishay Siliconix 功能描述:High Frequency 600-mA Synchronous Buck/Boost Converter |
| SI9165BQ-T1 | 功能描述:直流/直流開(kāi)關(guān)調(diào)節(jié)器 2MHz Controller RoHS:否 制造商:International Rectifier 最大輸入電壓:21 V 開(kāi)關(guān)頻率:1.5 MHz 輸出電壓:0.5 V to 0.86 V 輸出電流:4 A 輸出端數(shù)量: 最大工作溫度: 安裝風(fēng)格:SMD/SMT 封裝 / 箱體:PQFN 4 x 5 |
| SI9165BQ-T1-E3 | 功能描述:直流/直流開(kāi)關(guān)轉(zhuǎn)換器 Sync Buck/Boost Converter RoHS:否 制造商:STMicroelectronics 最大輸入電壓:4.5 V 開(kāi)關(guān)頻率:1.5 MHz 輸出電壓:4.6 V 輸出電流:250 mA 輸出端數(shù)量:2 最大工作溫度:+ 85 C 安裝風(fēng)格:SMD/SMT |
| SI9165DB | 功能描述:電源管理IC開(kāi)發(fā)工具 SI9165 Demo Board RoHS:否 制造商:Maxim Integrated 產(chǎn)品:Evaluation Kits 類型:Battery Management 工具用于評(píng)估:MAX17710GB 輸入電壓: 輸出電壓:1.8 V |
| SI9165DB-K | 制造商:Vishay Siliconix 功能描述:SI9165 DEMOB BOARD - Bulk 制造商:Vishay Siliconix 功能描述:IC, SYNCHRONOUS BUCK/BOOST CONV 20-TSSOP; Primary Input Voltage:6V; No. of Outputs:1; Output Voltage:1.3V; Output Current:600mA; No. of Pins:20; Operating Temperature Min:-25C; Operating Temperature Max:85C; Supply Voltage Max:6V ;RoHS Compliant: No |
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