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参数资料
| 型号： | FAN2103EMPX |
| 厂商： | Fairchild Semiconductor |
| 文件页数： | 10/14页 |
| 文件大小： | 0K |
| 描述： | IC REG BUCK SYNC ADJ 3A 25MLP |
| 标准包装： | 1 |
| 系列： | TinyBuck™ |
| 类型： | 降压（降压） |
| 输出类型： | 可调式 |
| 输出数： | 1 |
| 输出电压： | 3 V ~ 21 V |
| 输入电压： | 3 V ~ 24 V |
| PWM 型： | 电流模式 |
| 频率 - 开关： | 200kHz ~ 600kHz |
| 电流 - 输出： | 3A |
| 同步整流器： | 是 |
| 工作温度： | -40°C ~ 85°C |
| 安装类型： | 表面贴装 |
| 封装/外壳： | 25-MLP |
| 包装： | 标准包装 |
| 供应商设备封装： | 25-MLP（5x6） |
| 产品目录页面： | 1214 (CN2011-ZH PDF) |
| 配用： | FEB207-ND - BOARD EVAL FOR FAN2103 |
| 其它名称： | FAN2103EMPXDKR |
Circuit Description
Initialization
Once V CC exceeds the UVLO threshold and EN is HIGH,
the IC checks for an open or shorted FB pin before
releasing the internal soft-start ramp (SS).
If R1 is open (as shown in Figure 1), the error amplifier
output (COMP) is forced LOW and no pulses are
generated. After the SS ramp times out (T1.0), an under-
voltage latched fault occurs.
If the parallel combination of R1 and R BIAS is ≤ 1K Ω , the
internal SS ramp is not released and the regulator does
not start.
Soft-Start
Bias Supply
The FAN2103 requires a 5 V supply rail to bias the IC
and provide gate-drive energy and controller power.
Connect a ≥ 1.0 μf X5R or X7R decoupling capacitor
between VCC and PGND. Whenever the EN pin is
pulled up to V CC , the 5 V supply connected to V CC
should be turned ON after V IN comes up. If the power
supply is turned ON using EN pin with an external
control after V CC and V IN come up, the V CC and V IN
power sequencing is not relevant.
Since V CC is used to drive the internal MOSFET gates,
supply current is frequency and voltage dependent.
Approximate V CC current (I CC ) can be calculated using:
I CC ( mA ) = 4 . 58 + [( CC
Once internal SS ramp has charged to 0.8 V (T0.8), the
output voltage is in regulation. Until SS ramp reaches
1.0 V (T1.0), the “Fault Latch” is inhibited.
V ? 5
227
+ 0 . 013 ) ? ( f ? 128 )]
(1)
To avoid skipping the soft-start cycle, it is necessary to
apply V IN before V CC reaches its UVLO threshold.
Soft-start time is a function of oscillator frequency.
where frequency (f) is expressed in KHz.
Setting the Output Voltage
The output voltage of the regulator can be set from
EN
1.35V
0.8 V to ~80% of V IN by an external resistor divider (R1
and R BIAS in Figure 1).
FB
2400 CLKs
0.8V
Fault
The internal reference is 0.8 V with 650 nA, sourced
from the FB pin to ensure that if the pin is open, the
regulator does not start.
The external resistor divider is calculated using:
SS
1.0V
0.8V
Latch
Enable
0 . 8 V
R BIAS
=
V OUT ? 0 . 8 V
R 1
+ 650 nA
(2)
3200 CLKs
T0.8
Connect R BIAS between FB and AGND.
Setting the Frequency
4000 CLKs
T1.0
Oscillator frequency is determined by an external resistor,
R T, connected between the R(T) pin and AGND:
Figure 21. Soft-Start Timing Diagram
The regulator does not allow the low-side MOSFET to
f ( KHz ) =
10 6
( 65 ? R T ) + 135
(3)
R T ( K Ω ) =
operate in full synchronous rectification mode until
internal SS ramp reaches 95% of V REF (~0.76 V). This
helps the regulator start against pre-biased outputs (as
shown in Figure 16) and ensures that inductor current
where R T is expressed in K Ω .
(10 6 / f ) ? 135
65
(4)
does not "ratchet" up during the soft-start cycle.
V CC UVLO or toggling the EN pin discharges the SS and
resets the IC.
? 2007 Fairchild Semiconductor Corporation
FAN2103 ? Rev. 1.0.8
10
where frequency (f) is expressed in KHz.
The regulator does not start if R T is left open.
www.fairchildsemi.com
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相关代理商/技术参数 |
参数描述 |
|---|---|
| FAN2103EMPX_12 | 制造商:FAIRCHILD 制造商全称:Fairchild Semiconductor 功能描述:3 A, 24 V Input, Integrated Synchronous Buck Regulator |
| FAN2103MPX | 功能描述:直流/直流开关转换器 3A 24V INPUT RoHS:否 制造商:STMicroelectronics 最大输入电压:4.5 V 开关频率:1.5 MHz 输出电压:4.6 V 输出电流:250 mA 输出端数量:2 最大工作温度:+ 85 C 安装风格:SMD/SMT |
| FAN2103MPX_12 | 制造商:FAIRCHILD 制造商全称:Fairchild Semiconductor 功能描述:3 A, 24 V Input, Integrated Synchronous Buck Regulator |
| FAN2106 | 制造商:FAIRCHILD 制造商全称:Fairchild Semiconductor 功能描述:3-24V Input, 6A, High-Efficiency, Integrated Synchronous Buck Regulator |
| FAN2106_08 | 制造商:FAIRCHILD 制造商全称:Fairchild Semiconductor 功能描述:TinyBuck⑩ 6A, 24V Input, Integrated Synchronous Buck Regulator |
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