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参数资料
| 型号： | LTC3728IG |
| 厂商： | LINEAR TECHNOLOGY CORP |
| 元件分类： | 稳压器 |
| 英文描述： | 3 A DUAL SWITCHING CONTROLLER, 590 kHz SWITCHING FREQ-MAX, PDSO28 |
| 封装： | 0.209 INCH, PLASTIC, SSOP-28 |
| 文件页数： | 13/36页 |
| 文件大小： | 1661K |
| 代理商： | LTC3728IG |
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LTC3728
20
3728fg
APPLICATIONS INFORMATION
factor of (Duty Cycle)/(Efciency). For 5V regulators this
supply means connecting the EXTVCC pin directly to VOUT.
However, for 3.3V and other lower voltage regulators,
additional circuitry is required to derive INTVCC power
from the output.
The following list summarizes the four possible connec-
tions for EXTVCC:
1. EXTVCC Left Open (or Grounded). This will cause INTVCC
to be powered from the internal 5V regulator resulting in
an efciency penalty of up to 10% at high input voltages.
2. EXTVCC Connected Directly to VOUT. This is the normal
connection for a 5V regulator and provides the highest
efciency.
3. EXTVCC Connected to an External Supply. If an external
supply is available in the 5V to 7V range, it may be used
to power EXTVCC providing it is compatible with the
MOSFET gate drive requirements.
4. EXTVCCConnectedtoanOutput-DerivedBoostNetwork.
For 3.3V and other low voltage regulators, efciency
gains can still be realized by connecting EXTVCC to an
output-derived voltage that has been boosted to greater
than 4.7V. This can be done with either the inductive
boost winding as shown in Figure 6a or the capacitive
charge pump shown in Figure 6b. The charge pump
has the advantage of simple magnetics.
Topside MOSFET Driver Supply (CB, DB)
External bootstrap capacitors CB connected to the BOOST
pins supply the gate drive voltages for the topside MOS-
FETs. Capacitor CB in the Functional Diagram is charged
though external diode DB from INTVCC when the SW pin
is low. When one of the topside MOSFETs is to be turned
on, the driver places the CB voltage across the gate-source
of the desired MOSFET. This enhances the MOSFET and
turns on the topside switch. The switch node voltage, SW,
rises to VIN and the BOOST pin follows. With the topside
MOSFET on, the boost voltage is above the input supply:
VBOOST = VIN + VINTVCC. The value of the boost capacitor
CB needs to be 100 times that of the total input capacitance
of the topside MOSFET(s). The reverse breakdown of the
external Schottky diode must be greater than VIN(MAX).
When adjusting the gate drive level, the nal arbiter is the
total input current for the regulator. If a change is made
and the input current decreases, then the efciency has
improved. If there is no change in input current, then there
is no change in efciency.
Output Voltage
The LTC3728 output voltages are each set by an exter-
nal feedback resistive divider carefully placed across
the output capacitor. The resultant feedback signal is
compared with the internal precision 0.800V voltage
EXTVCC
FCB
SGND
VIN
TG1
SW
BG1
PGND
LTC3728
RSENSE
VOUT
VSEC
+
COUT
+
1 F
3728 F06a
N-CH
R6
+
CIN
VIN
T1
1:N
OPTIONAL EXTVCC
CONNECTION
5V < VSEC < 7V
R5
EXTVCC
VIN
TG1
SW
BG1
PGND
LTC3728
RSENSE
VOUT
VN2222LL
+
COUT
3728 F06b
N-CH
+
CIN
+
1 F
VIN
L1
BAT85
0.22 F
Figure 6a. Secondary Output Loop and EXTVCC Connection
Figure 6b. Capacitive Charge Pump for EXTVCC
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相关代理商/技术参数 |
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| LTC3728IG#PBF | 功能描述:IC REG CTRLR BUCK PWM CM 28-SSOP RoHS:是 类别:集成电路 (IC) >> PMIC - 稳压器 - DC DC 切换控制器 系列:PolyPhase® 标准包装:4,500 系列:PowerWise® PWM 型:控制器 输出数:1 频率 - 最大:1MHz 占空比:95% 电源电压:2.8 V ~ 5.5 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 ~ 125°C 封装/外壳:6-WDFN 裸露焊盘 包装:带卷 (TR) 配用:LM1771EVAL-ND - BOARD EVALUATION LM1771 其它名称:LM1771SSDX |
| LTC3728IG#TRPBF | 功能描述:IC REG CTRLR BUCK PWM CM 28-SSOP RoHS:是 类别:集成电路 (IC) >> PMIC - 稳压器 - DC DC 切换控制器 系列:PolyPhase® 标准包装:4,500 系列:PowerWise® PWM 型:控制器 输出数:1 频率 - 最大:1MHz 占空比:95% 电源电压:2.8 V ~ 5.5 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 ~ 125°C 封装/外壳:6-WDFN 裸露焊盘 包装:带卷 (TR) 配用:LM1771EVAL-ND - BOARD EVALUATION LM1771 其它名称:LM1771SSDX |
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