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參數(shù)資料
| 型號： | MCP1601 |
| 廠商： | Microchip Technology Inc. |
| 英文描述： | 500 mA Synchronous BUCK Regulator |
| 中文描述： | 500毫安同步降壓穩(wěn)壓器 |
| 文件頁數(shù)： | 10/22頁 |
| 文件大?。?/td> | 585K |
| 代理商： | MCP1601 |
MCP1601
DS21762A-page 10
2003 Microchip Technology Inc.
4.0
DEVICE OPERATION
The MCP1601 is a synchronous DC/DC converter with
integrated switches. Developed to provide high effi-
ciency across a wide line and load range, the
MCP1601 integrates the three modes of operation
described below. In addition to three operating modes,
the MCP1601 also integrates many features that mini-
mize external circuitry, saving board space and cost.
With two external resistors used to set the output volt-
age, the MCP1601 output is adjustable from 0.9V to
V
IN
.
4.1
Operating Modes
The MCP1601 has three distinct modes of operation,
with each one optimized for a specific operating condi-
tion commonly encountered in handheld portable
power applications.
4.1.1
FEEDFORWARD VOLTAGE PULSE
WIDTH MODULATION (PWM) MODE
The Pulse Width Modulation (PWM) mode of operation
is desired when operating from typical to maximum out-
put currents with the proper head room voltage at the
input. This mode of operation optimizes efficiency and
noise by switching at a fixed frequency. Typical output
ripple voltage is less than 10 mV when using a 10 μH
inductor and 10 μF ceramic capacitor. The internal
operating frequency of the MCP1601 is 750 kHz, nom-
inal. The duty cycle, or
“
ON
”
time, of the high-side, inte-
grated, P-Channel MOSFET is determined by the
continuous mode BUCK transfer function. For the con-
tinuous inductor current case, the duty cycle can be
approximated by V
OUT
/V
IN
. The integrated high-side
BUCK P-Channel switch will conduct for the
“
on
”
time.
At the end of the
“
on
”
time, the high-side P-Channel
switch is turned off and the integrated, low-side, N-
Channel synchronous switch is turned on to freewheel
the inductor current. The PWM mode architecture
employed in the MCP1601 is a feedforward voltage
mode control and feeds the input voltage into the PWM
oscillator ramp. This information is used to quickly
change the operating duty cycle in the event of a sud-
den input voltage change. The effects on the output
voltage are minimized. To force the MCP1601 into
PWM mode, the SYNC/PWM pin should be tied to a
logic high. The forced PWM mode should be used for
applications that require the fastest transient response
from light load to heavy load or applications that require
a single switching frequency independent of load.
An external oscillator between 850 kHz and 1 MHz can
be connected to the SYNC/PWM pin for synchroniza-
tion to an external clock source. The MCP1601 will
always operate in the PWM mode when synchronized
to an external oscillator.
4.1.2
PULSE FREQUENCY MODULATION
(PFM) MODE
The MCP1601 is also capable of operating in a pulse
frequency modulation mode. This mode of operation is
desired for applications that have very long periods of
inactivity and the output current requirement placed on
the MCP1601 is very low. By entering the PFM mode of
operation, the switching frequency becomes mainly a
function of load current and will decrease as the load
current decreases. By switching slower, the energy
used turning
“
on
”
and
“
off
”
the high-side P-Channel and
low-side N-Channel is reduced, making the PFM mode
more efficient with light output load currents. When
load activity is encountered, the MCP1601 will auto-
matically switch from the PFM mode to the fixed fre-
quency PWM mode by sensing the increase in load
current. The auto PWM/PFM mode is selected by plac-
ing a logic low at the SYNC/PWM input pin. If an exter-
nal clock is used to synchronize the MCP1601
switching frequency, the PFM mode is automatically
disabled.
To enter the PFM mode of operation, the SYNC/PWM
pin must be held to a logic low level and the peak induc-
tor current, sensed internal to the MCP1601, is below
the internal PFM threshold for more than 1024 clock
cycles. If both of these conditions are met, the
MCP1601 will enter the PFM mode. While in the PFM
mode, the MCP1601 will disable the low-side N-Chan-
nel switch to optimize efficiency at low operating cur-
rents. A cycle will begin by turning on the high-side
P-Channel switch and will end when the output voltage
exceeds a predetermined voltage set point. If the peak
inductor current exceeds the internal PFM mode cur-
rent threshold prior to the output voltage exceeding the
voltage set point, the load current has increased and
the MCP1601 will automatically switch to PWM opera-
tion. The typical hysteresis on the PFM comparator is
6 mV. The typical output ripple voltage is below 40 mV
when using a 10 μH inductor and 10 μF ceramic output
capacitor when V
IN
= 4.2V. For proper PFM mode oper-
ation, the value of the external inductor and the exter-
nal capacitor should be the same. For example, when
using a 10 μH inductor, a 10 μF capacitor should be
used. When using a 22 μH inductor, a 22 μF capacitor
should be used.
4.1.3
LOW DROP OUT (LDO) MODE
When the input voltage to the MCP1601 is decreasing
and approaches the set output voltage level, the duty
cycle increases to a maximum of 90% (typically). To
continue to regulate the output to as high a voltage as
possible, the MCP1601 enters the low drop out mode
of operation. In this mode, the high-side P-Channel
MOSFET acts like a saturated LDO. This mode allows
the operation of the load circuitry down to the minimum
input supply that is typical in battery-powered
applications.
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相關(guān)代理商/技術(shù)參數(shù) |
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|---|---|
| MCP1601_13 | 制造商:MICROCHIP 制造商全稱:Microchip Technology 功能描述:500 mA Synchronous BUCK Regulator |
| MCP1601EV | 功能描述:電源管理IC開發(fā)工具 MCP1601 Buck Reg Eval Brd RoHS:否 制造商:Maxim Integrated 產(chǎn)品:Evaluation Kits 類型:Battery Management 工具用于評估:MAX17710GB 輸入電壓: 輸出電壓:1.8 V |
| MCP1601-I/MS | 功能描述:開關(guān)變換器、穩(wěn)壓器與控制器 500mA Sych Buck RoHS:否 制造商:Texas Instruments 輸出電壓:1.2 V to 10 V 輸出電流:300 mA 輸出功率: 輸入電壓:3 V to 17 V 開關(guān)頻率:1 MHz 工作溫度范圍: 安裝風(fēng)格:SMD/SMT 封裝 / 箱體:WSON-8 封裝:Reel |
| MCP1601-I/MS | 制造商:Microchip Technology Inc 功能描述:BUCK CONVERTER SMD 1601 MSOP8 |
| MCP1601T-I/MS | 功能描述:開關(guān)變換器、穩(wěn)壓器與控制器 500mA Sych Buck RoHS:否 制造商:Texas Instruments 輸出電壓:1.2 V to 10 V 輸出電流:300 mA 輸出功率: 輸入電壓:3 V to 17 V 開關(guān)頻率:1 MHz 工作溫度范圍: 安裝風(fēng)格:SMD/SMT 封裝 / 箱體:WSON-8 封裝:Reel |
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