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参数资料
| 型号： | MAX8621YETG+T |
| 厂商： | Maxim Integrated Products |
| 文件页数： | 14/18页 |
| 文件大小： | 0K |
| 描述： | IC PMIC W/DC-DC SUP 24-TQFN |
| 产品培训模块： | Lead (SnPb) Finish for COTS Obsolescence Mitigation Program |
| 标准包装： | 2,500 |
| 应用： | 手持/移动设备 |
| 电源电压： | 2.6 V ~ 5.5 V |
| 工作温度： | -40°C ~ 85°C |
| 安装类型： | 表面贴装 |
| 封装/外壳： | 24-WFQFN 裸露焊盘 |
| 供应商设备封装： | 24-TQFN-EP（4x4） |
| 包装： | 带卷 (TR) |
Dual Step-Down DC-DC Power-Management ICs
for Portable Devices
( )
× R DC ( INDUCTOR )
( )
C 6 = × 10 Siemens
× R DC ( INDUCTOR )
( )
( )
P LOSS ( OUT 3 ) = I OUT 3 × ( V IN V OUT 3 )
P LOSS ( OUT 4 ) = I OUT 4 × ( V IN V OUT 4 )
Output Capacitor
The output capacitors, C7 and C9 in Figure 3, are
required to keep the output voltage ripple small and to
ensure regulation loop stability. C7 and C9 must have
low impedance at the switching frequency. Ceramic
capacitors with X5R or X7R dielectric are highly recom-
mended due to their small size, low ESR, and small
temperature coefficients. Due to the unique feedback
network, the output capacitance can be very low. For
most applications, a 2.2μF capacitor is sufficient. For
optimum load-transient performance and very low out-
put ripple, the output capacitor value in μF should be
equal or larger than the inductor value in μH.
Feed-Forward Capacitor
The feed-forward capacitors, C FF (C6 and C8 in Figure
3), set the feedback loop response, control the switch-
ing frequency, and are critical in obtaining the best effi-
ciency possible. Choose a small ceramic X7R
capacitor with value given by:
L1
R 1
Select the closest standard value to C FF as possible.
For BUCK2, C8, R3, and L1 are calculated using the
same methods.
LDO Output Capacitor and
Regulator Stability
Connect a 4.7μF ceramic capacitor between OUT1 and
ground, and a second 4.7μF ceramic capacitor
between OUT2 and ground for 300mA applications. For
150mA applications, 2.2μF ceramic capacitors can be
used for OUT1 and OUT2. Connect a 2.2μF ceramic
capacitor between OUT3 and ground, and a second
2.2μF ceramic capacitor between OUT4 and ground.
The LDO output capacitor’s (C OUT ) equivalent series
resistance (ESR) affects stability and output noise. Use
output capacitors with an ESR of 0.1 Ω or less to ensure
stability and optimum transient response. Surface-
mount ceramic capacitors have very low ESR and are
commonly available in values up to 10μF. Connect
C OUT_ as close to the IC as possible to minimize the
impact of PC board trace inductance.
Thermal Considerations
The MAX8621Y/MAX8621Z total power dissipation, P D ,
is estimated using the following equations:
P D = P LOSS ( BUCK 1 ) + P LOSS ( BUCK 2 ) + P LOSS ( OUT 1 )
+ P LOSS ( OUT 2 ) + P LOSS ( OUT 3 ) + P LOSS ( OUT 4 )
P LOSS ( BUCK 1 ) = P IN ( BUCK 1 ) × 1 ? η / 100
2
? I BUCK 1
P LOSS ( BUCK 2 ) = P IN ( BUCK 2 ) × 1 ? η / 100
2
? I BUCK 2
P LOSS ( OUT 1 ) = I OUT 1 × V IN ? V OUT 1
P LOSS ( OUT 2 ) = I OUT 2 × V IN ? V OUT 2
?
?
where P IN(BUCK1) is the input power for BUCK1, η is the
step-down converter efficiency, and R DC(INDUCTOR) is
the inductor’s DC resistance.
For example, operating with V IN = 3.7V, V BUCK1 = 1.376V,
V BUCK2 = 1.8V, V OUT1 = V OUT2 = 2.6V, V OUT3 = 1.8V,
V OUT4 = 3V, I BUCK1 = I BUCK2 = 300mA, I OUT1 = I OUT2 =
330mA, I OUT3 = I OUT4 = 100mA, P IN(BUCK1) = 516mW
and η = 80%, P IN(BUCK2) = 651mW and η = 83%:
P LOSS ( OUT 1 ) = P LOSS ( OUT 2 ) = 363 mW
P LOSS ( OUT 3 ) = 190 mW
P LOSS ( OUT 4 ) = 70 mW
P LOSS ( BUCK 1 ) = 94 mW
P LOSS ( BUCK 2 ) = 102 mW
P D = 363 mW + 363 mW + 190 mW + 70 mW
+ 94 mW + 102 mW = 1182 mW
14
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相关代理商/技术参数 |
参数描述 |
|---|---|
| MAX8621ZETG | 功能描述:PMIC 解决方案 Dual Step-Down PMIC for Portable Devices RoHS:否 制造商:Texas Instruments 安装风格:SMD/SMT 封装 / 箱体:QFN-24 封装:Reel |
| MAX8621ZETG+ | 功能描述:PMIC 解决方案 Dual Step-Down PMIC for Portable Devices RoHS:否 制造商:Texas Instruments 安装风格:SMD/SMT 封装 / 箱体:QFN-24 封装:Reel |
| MAX8621ZETG+T | 功能描述:PMIC 解决方案 Dual Step-Down PMIC for Portable Devices RoHS:否 制造商:Texas Instruments 安装风格:SMD/SMT 封装 / 箱体:QFN-24 封装:Reel |
| MAX8621ZETG-T | 功能描述:PMIC 解决方案 Dual Step-Down PMIC for Portable Devices RoHS:否 制造商:Texas Instruments 安装风格:SMD/SMT 封装 / 箱体:QFN-24 封装:Reel |
| MAX8621ZEVKIT | 制造商:Maxim Integrated Products 功能描述:DUAL STEP-DOWN POWER MANAGEMENT IC - Rail/Tube |
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