参数资料
型号: MCP1624T-I/MC
厂商: Microchip Technology
文件页数: 11/28页
文件大小: 0K
描述: IC BOOST SYNC REG PWM/PFM 8DFN
标准包装: 3,300
应用: 转换器,PIC? 微控制器
输入电压: 0.8 V ~ 5.5 V
输出数: 1
输出电压: 2 V ~ 5.5 V
工作温度: -40°C ~ 85°C
安装类型: 表面贴装
封装/外壳: 8-VFDFN 裸露焊盘
供应商设备封装: 8-DFN(2x3)
包装: 带卷 (TR)
MCP1623/24
4.2
Functional Description
During this time, the boost switch current is limited to
The MCP1623/24 is a compact, high-efficiency, fixed
frequency, step-up DC-DC converter that provides an
easy-to-use power supply solution for PIC
microcontroller applications powered by either one-cell,
two-cell, or three-cell alkaline, NiCd, or NiMH, or one-
cell Li-Ion or Li-Polymer batteries.
Figure 4-1 depicts the functional block diagram of the
MCP1623/24.
50% of its nominal value. Once the output voltage
reaches 1.6V, normal closed-loop PWM operation is
initiated.
The MCP1623/24 charges an internal capacitor with a
very weak current source. The voltage on this
capacitor, in turn, slowly ramps the current limit of the
boost switch to its nominal value. The soft-start
capacitor is completely discharged in the event of a
commanded shutdown or a thermal shutdown.
4.2.1
LOW-VOLTAGE START-UP
There is no undervoltage lockout feature for the
The MCP1623/24 is capable of starting from a low input
voltage. Start-up voltage is typically 0.65V for a 3.3V
output and 1 mA resistive load.
When enabled, the internal start-up logic turns the
rectifying P-Channel switch on until the output
capacitor is charged to a value close to the input
voltage. The rectifying switch is current limited during
this time. After charging the output capacitor to the
input voltage, the device starts switching. If the input
voltage is below 1.6V, the device runs open-loop with a
fixed duty cycle of 70% until the output reaches 1.6V.
VOUT
MCP1623/24. The device will start-up at the lowest
possible voltage and run down to the lowest possible
voltage. For typical battery applications, this may result
in “motor-boating” for deeply discharged batteries.
VIN
SW
EN
INTERNAL
BIAS
GATE DRIVE
AND
SHUTDOWN
CONTROL
LOGIC
DIRECTION
CONTROL
SOFT-START
.3V
0V
I ZERO
I LIMIT
I SENSE
GND
OSCILLATOR
SLOPE
COMP.
Σ
PWM/PFM
LOGIC
1.21V
FB
EA
FIGURE 4-1:
MCP1623/24 Block Diagram.
? 2011 Microchip Technology Inc.
DS41420C-page 11
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