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参数资料
| 型号： | S-8521C31MC-BTQ-T2 |
| 元件分类： | 稳压器 |
| 英文描述： | 0.05 A SWITCHING CONTROLLER, 75 kHz SWITCHING FREQ-MAX, PDSO5 |
| 封装： | SOT-23, 5 PIN |
| 文件页数： | 15/43页 |
| 文件大小： | 488K |
| 代理商： | S-8521C31MC-BTQ-T2 |
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STEP-DOWN, PWM CONTROL or PWM / PFM SWITCHABLE SWITCHING REGULATOR CONTROLLOR
S-8520 / 8521 Series
Rev.7.5_00
22
Seiko Instruments Inc.
Application Circuits
1. External adjustment of output voltage
The S-8520 / 8521 Series allows you to adjust the output voltage or to set the output voltage to a value
over the preset output voltage range (6 V) of the products of this series, when external resistances (RA
and RB), and capacitor (CC) are added, as illustrated in Figure 14. Moreover, a temperature gradient
can be obtained by inserting a thermistor or other element in series with RA and RB.
S-8520/8521Series
CC
RA
RB
D1
VOUT
+
VIN
OUT
EXT
+
Reference
voltage source
with soft start
+
R2
R1
OFF
/
ON
VSS
Oscillation
circuit
PWM control or
PWM/PFM switching
control circuit
Figure 14
Caution The above connection diagram and constant will not guarantees successful operation.
Perform through evaluation using the actual application to set the constant.
The S-8520 / 8521 Series have an internal impedance of R1 and R2 between the VOUT pin and the VSS
pin, as shown in Figure 14.
Therefore, OUT (the output voltage) is determined by the output voltage value (VOUT) of the S-8520 / 8521
Series, and the ratio of the parallel resistance value of external resistance (RB) and internal resistances
(R1
+R2) of the IC, to external resistance (RA). The output voltage is expressed by the following equation:
OUT
=VOUT+VOUT×RA÷(RB//
*1(R
1
+ R2))
The voltage accuracy of the OUT set by resistances (RA and RB) is not only affected by the IC's output
voltage accuracy (VOUT
±2.4 %), but also by the absolute precision of external resistances (RA and RB) in
use and the absolute value deviations of internal resistances (R1 and R2) in the IC.
Let us designate the maximum deviations of the absolute value of RA and RB by RAmax and RBmax,
respectively, the minimum deviations by RAmin and RBmin, respectively, and the maximum and minimum
deviations of the absolute value of R1 and R2 in the IC by (R1
+R2) max and (R1+R2) min, respectively.
Then, the minimum deviation value OUTmin and the maximum deviation value OUTmax of the OUT are
expressed by the following equations:
OUT min.
=VOUT×0.976+VOUT×0.976×RAmin.÷(RBmax//(R1+R2) max.)
OUT max.
=VOUT×1.024+VOUT×1.024×RAmax.÷(RBmin//(R1+R2) min.)
The voltage accuracy of the OUT cannot be made higher than the output voltage accuracy (VOUT
±2.4 %) of
the IC itself, without adjusting the RA and RB involved. The closer the voltage value of the output OUT and
the output voltage value (VOUT) of the IC are brought to one other, the more the output voltage remains
immune to deviations in the absolute accuracy of RA and RB and the absolute value of R1 and R2 in the IC. In
particular, to suppress the influence of deviations in R1 and R2 in the IC, a major contributor to deviations in
the OUT, the RA and RB must be limited to a much smaller value than that of R1 and R2 in the IC.
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相关代理商/技术参数 |
参数描述 |
|---|---|
| S-8521C31MC-BTQT2G | 功能描述:DC/DC 开关控制器 3.1V Step-Dn PWM/PFM RoHS:否 制造商:Texas Instruments 输入电压:6 V to 100 V 开关频率: 输出电压:1.215 V to 80 V 输出电流:3.5 A 输出端数量:1 最大工作温度:+ 125 C 安装风格: 封装 / 箱体:CPAK |
| S-8521C31MC-BXQ-T2 | 制造商:SII 制造商全称:Seiko Instruments Inc 功能描述:PWM CONTROL & PWM/PFM CONTROL STEP-DOWN SWITCHING REGULATOR-CONTROLLERS |
| S-8521C32MC-BTR-T2 | 功能描述:DC/DC 开关控制器 3.2V Step-Dn PWM/PFM RoHS:否 制造商:Texas Instruments 输入电压:6 V to 100 V 开关频率: 输出电压:1.215 V to 80 V 输出电流:3.5 A 输出端数量:1 最大工作温度:+ 125 C 安装风格: 封装 / 箱体:CPAK |
| S-8521C32MC-BTRT2G | 功能描述:DC/DC 开关控制器 3.2V Step-Dn PWM/PFM RoHS:否 制造商:Texas Instruments 输入电压:6 V to 100 V 开关频率: 输出电压:1.215 V to 80 V 输出电流:3.5 A 输出端数量:1 最大工作温度:+ 125 C 安装风格: 封装 / 箱体:CPAK |
| S-8521C32MC-BXR-T2 | 制造商:SII 制造商全称:Seiko Instruments Inc 功能描述:PWM CONTROL & PWM/PFM CONTROL STEP-DOWN SWITCHING REGULATOR-CONTROLLERS |
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