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参数资料
| 型号： | S-8338AAHB-T8T1G |
| 元件分类： | 稳压器 |
| 英文描述： | 0.16 A SWITCHING CONTROLLER, 1246.3 kHz SWITCHING FREQ-MAX, PDSO8 |
| 封装： | LEAD FREE, TSSOP-8 |
| 文件页数： | 9/51页 |
| 文件大小： | 446K |
| 代理商： | S-8338AAHB-T8T1G |
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STEP-UP, 1.2 MHz HIGH-FREQUENCY, PWM CONTROL SWITCHING REGULATOR CONTROLLER
Rev.4.0_00
S-8337/8338 Series
Seiko Instruments Inc.
17
External Parts Selection
1. Inductor
The inductance has a strong influence on the maximum output current (IOUT) and efficiency (η).
The peak current (IPK) increases by decreasing L and the stability of the circuit improves and IOUT
increases. If L is decreased further, the efficiency falls, and IOUT decreases if the current drive
capability of the external transistor is insufficient.
The loss of IPK by the switching transistor decreases by increasing L and the efficiency becomes
maximum at a certain L value. Further increasing L decrease the efficiency due to the loss of the DC
resistance of the inductor. IOUT also decreases.
If the oscillation frequency is higher, a smaller L value can be chosen, making the inductor smaller. In
the S-8337/8338 Series, the oscillation frequency can be varied within the range of 286 kHz to 1.133
MHz by the external resistor, so select an L value best suited to the frequency. The recommended
value is between 2.2
μH and 22 μH.
When selecting an inductor, note the allowable current of the inductor. If a current exceeding this
allowable current flows through the inductor, magnetic saturation occurs, substantially lowering the
efficiency and increasing the current, which results in damage to the IC.
Therefore, select an inductor so that IPK does not exceed the allowable current. IPK is expressed by
the following equations in the discontinuous mode and continuous mode.
)
mode
ous
discontinu
(
L
fosc
)
V
(V
I
2
I
IN
D
OUT
PK
+
=
..................................................................(17)
mode)
s
(continuou
L
fosc
)
V
(V
2
V
)
V
(V
I
V
I
D
OUT
IN
D
OUT
IN
D
OUT
PK
+
+
+
=
................................................................(18)
fOSC = Oscillation frequency, VD 0.4 V.
2. Diode
Use an external diode that meets the following requirements.
Low forward voltage
High switching speed
Reverse breakdown voltage: V
OUT + [Spike voltage] or more
Rated current: I
PK or more
3. Capacitors (CIN, CL)
The capacitor on the input side (CIN) can lower the supply impedance and level the input current for
better efficiency. Select CIN according to the impedance of the power supply to be used.
The capacitor on the output side (CL) is used to smooth the output voltage. Select an appropriate
capacitance value based on the I/O conditions and load conditions. A capacitance of 10
μF or more is
recommended.
By adjusting the phase compensation of the feedback loop using the external resistor (RZ) and
capacitor (CZ), a ceramic capacitor can be used as the capacitor on the output side. If a capacitor
whose equivalent series resistance is between 30 m
Ω and 500 mΩ is used as the output capacitor, the
adjustable range of the phase compensation is wider; however, note that other characteristics may be
affected by ripple voltage or other conditions at this time. The optimal capacitor differs depending on
the L value, capacitance value, wiring, and application (output load), so select the capacitor after
performing sufficient evaluation under the actual usage conditions.
相关PDF资料 |
PDF描述 |
|---|---|
| S-8338ABCA-P8T1G | 0.16 A SWITCHING CONTROLLER, 1246.3 kHz SWITCHING FREQ-MAX, PDSO8 |
| S-80132ANPF-JCRTFGG | 1-CHANNEL POWER SUPPLY SUPPORT CKT, PDSO4 |
| SC101R8KT | 1 ELEMENT, 1.8 uH, GENERAL PURPOSE INDUCTOR |
| SC10820KT | 1 ELEMENT, 82 uH, GENERAL PURPOSE INDUCTOR |
| SC153R9K | 1 ELEMENT, 2.3 uH, GENERAL PURPOSE INDUCTOR |
相关代理商/技术参数 |
参数描述 |
|---|---|
| S-8338ABAA-P8T1G | 制造商:Seiko Instruments Inc (SII) 功能描述: |
| S-8338ABAA-T8T1G | 制造商:Seiko Instruments Inc (SII) 功能描述: |
| S-8338ABAC-P8T1G | 制造商:Seiko Instruments Inc (SII) 功能描述:STEPUP1.2MHZ PWM SWR |
| S-8338ABCA-P8T1G | 制造商:Seiko Instruments Inc (SII) 功能描述:STEPUP1.2MHZ PWM SWR |
| S-8338ABCB-P8T1G | 制造商:Seiko Instruments Inc (SII) 功能描述:STEPUP1.2MHZ PWM SWR |
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