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参数资料
| 型号： | ZL6105ALAFTK |
| 厂商： | Intersil |
| 文件页数： | 18/35页 |
| 文件大小： | 0K |
| 描述： | IC REG CTRLR BUCK PWM VM 36-QFN |
| 标准包装： | 1,000 |
| PWM 型： | 电压模式 |
| 输出数： | 1 |
| 频率 - 最大： | 1.4MHz |
| 占空比： | 95% |
| 电源电压： | 3 V ~ 14 V |
| 降压： | 是 |
| 升压： | 无 |
| 回扫： | 无 |
| 反相： | 无 |
| 倍增器： | 无 |
| 除法器： | 无 |
| Cuk： | 无 |
| 隔离： | 无 |
| 工作温度： | -40°C ~ 85°C |
| 封装/外壳： | 36-VFQFN 裸露焊盘 |
| 包装： | 带卷 (TR) |
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ZL6105
Without capacitive filtering near the power supply circuit, this
current would flow through the supply bus and return planes,
I toprms = I Lrms × D
(EQ. 19)
P QH = 0 . 05 × V OUT × I OUT
R DS ( ON ) =
( I )
t SW =
Q g
coupling noise into other system circuitry. The input capacitors
should be rated at 1.2x the ripple current calculated in Equation
13 to avoid overheating of the capacitors due to the high ripple
current, which can cause premature failure. Ceramic capacitors
with X7R or X5R dielectric with low ESR and 1.1x the maximum
expected input voltage are recommended.
BOOTSTRAP CAPACITOR SELECTION
The high-side driver boost circuit utilizes an external Schottky diode
(D B ) and an external bootstrap capacitor (C B ) to supply sufficient
gate drive for the high-side MOSFET driver. D B should be a 20mA,
30V Schottky diode or equivalent device and C B should be a 1μF
ceramic type rated for at least 6.3V.
QL SELECTION
The bottom MOSFET should be selected primarily based on the
device’s r DS(ON) and secondarily based on its gate charge. To
choose QL, use Equation 14 and allow 2% to 5% of the output
power to be dissipated in the r DS(ON) of QL (lower output voltages
and higher step-down ratios will be closer to 5%):
Calculate a starting r DS(ON) as shown in Equation 20. This
equation uses 5% as an example:
(EQ. 20)
P QH
(EQ. 21)
2
toprms
Select a MOSFET and calculate the resulting gate drive current.
Verify that the combined gate drive current from QL and QH does
not exceed 80mA.
Next, calculate the switching time using Equation 22:
(EQ. 22)
I gdr
where Q g is the gate charge of the selected QH and I gdr is the
peak gate drive current available from the ZL6105.
P QL = 0 . 05 × V OUT × I OUT
(EQ. 14)
Although the ZL6105 has a typical gate drive current of 3A, use
the minimum guaranteed current of 2A for a conservative
I botrms = I Lrms × 1 ? D
R DS ( ON ) =
P QL
( I botrms ) 2
P swtop = V INM × t sw × I OUT × f sw
P QHtot = P QH + P swtop
I g = f SW × Q g
T j max = T pcb + ( P Q × R th )
P QL = f sw × Q g × V INM
Calculate the RMS current in QL as shown in Equation 15:
(EQ. 15)
Calculate the desired maximum r DS(ON) as shown in Equation 16:
(EQ. 16)
Note that the r DS(ON) given in the manufacturer’s datasheet is
measured at +25°C. The actual r DS(ON) in the end-use application
will be much higher. For example, a Vishay Si7114 MOSFET with
a junction temperature of +125°C has an r DS(ON) that is 1.4x
higher than the value at +25°C. Select a candidate MOSFET, and
calculate the required gate drive current as shown in Equation
(EQ. 17)
Keep in mind that the total allowed gate drive current for both QH
and QL is 80mA.
MOSFETs with lower r DS(ON) tend to have higher gate charge
requirements, which increases the current and resulting power
required to turn them on and off. Since the MOSFET gate drive
circuits are integrated in the ZL6105, this power is dissipated in
the ZL6105 according to the Equation 18:
(EQ. 18)
design. Using the calculated switching time, calculate the
switching power loss in QH using Equation 23:
(EQ. 23)
The total power dissipated by QH is given by Equation 24:
(EQ. 24)
MOSFET THERMAL CHECK
Once the power dissipations for QH and QL have been calculated,
the MOSFETs junction temperature can be estimated. Using the
junction-to-case thermal resistance (R th ) given in the MOSFET
manufacturer’s datasheet and the expected maximum printed
circuit board temperature, calculate the junction temperature as
shown in Equation 25:
(EQ. 25)
CURRENT SENSING COMPONENTS
Once the current sense method has been selected (Refer to
components are selected as indicated in the following.
When using the inductor DCR sensing method, the user must
also select an R/C network comprised of R1 and CL (see
Figure 11).
QH SELECTION
In addition to the r DS(ON) loss and gate charge loss, QH also has
switching loss. The procedure to select QH is similar to the
procedure for QL. First, assign 2% to 5% of the output power to
ZL
GH
SW
GL
R1
CL
be dissipated in the r DS(ON) of QH using Equation 18 for QL. As
was done with QL, calculate the RMS current as shown in
Equation 19:
18
R2
ISENA
ISENB
FIGURE 11. DCR CURRENT SENSING
FN6906.5
December 19, 2013
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相关代理商/技术参数 |
参数描述 |
|---|---|
| ZL6105ALAFTKR5546 | 功能描述:DC/DC 开关控制器 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 |
| ZL6105ALAFTKR5549 | 制造商:Intersil Corporation 功能描述:ADAPTIVE DIGITAL DC-DC CONTROLLER W/ DRIVERS & I-SHARING FE0 - Tape and Reel |
| ZL6105ALAFTKR5553 | 制造商:Intersil Corporation 功能描述:ADAPTIVE DIGITAL DC-DC CONTROLLER W/ DRIVERS & I-SHARING MOD - Tape and Reel |
| ZL6105ALAFTKR5554 | 制造商:Intersil Corporation 功能描述:ADAPTIVE DIGITAL DC-DC CONTROLLER W/ DRIVERS & I-SHARING MOD - Tape and Reel |
| ZL6105ALAFTR5546 | 功能描述:IC REG CTRLR BUCK PWM VM 36-QFN RoHS:是 类别:集成电路 (IC) >> PMIC - 稳压器 - DC DC 切换控制器 系列:- 产品培训模块:Lead (SnPb) Finish for COTS Obsolescence Mitigation Program 标准包装:2,500 系列:- PWM 型:电流模式 输出数:1 频率 - 最大:275kHz 占空比:50% 电源电压:18 V ~ 110 V 降压:无 升压:无 回扫:无 反相:无 倍增器:无 除法器:无 Cuk:无 隔离:是 工作温度:-40°C ~ 85°C 封装/外壳:8-SOIC（0.154"，3.90mm 宽） 包装:带卷 (TR) |
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