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参数资料
| 型号： | LTC1438XCG#TR |
| 厂商： | Linear Technology |
| 文件页数： | 16/32页 |
| 文件大小： | 0K |
| 描述： | IC REG CTRLR BUCK PWM CM 28-SSOP |
| 标准包装： | 2,000 |
| PWM 型： | 电流模式 |
| 输出数： | 2 |
| 频率 - 最大： | 138kHz |
| 占空比： | 99% |
| 电源电压： | 3.5 V ~ 30 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： | 0°C ~ 70°C |
| 封装/外壳： | 28-SSOP（0.209"，5.30mm 宽） |
| 包装： | 带卷 (TR) |
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LTC1438/LTC1439
APPLICATIO N S I N FOR M ATIO N
in an efficiency penalty of up to 10% at high input
voltages.
2. EXTV CC connected directly to V OUT . This is the normal
connection for a 5V regulator and provides the highest
efficiency.
3. EXTV CC connected to an output-derived boost network.
For 3.3V and other low voltage regulators, efficiency
gains can still be realized by connecting EXTV CC to an
output-derived voltage which has been boosted to
greater than 4.8V. This can be done with either the
inductive boost winding as shown in Figure 4a or the
capacitive charge pump shown in Figure 4b. The charge
pump has the advantage of simple magnetics.
4. EXTV CC connected to an external supply. If an external
supply is available in the 5V to 10V range (EXTV CC ≤ V IN )
it may be used to power EXTV CC providing it is compat-
ible with the MOSFET gate drive requirements. When
driving standard threshold MOSFETs, the external sup-
ply must be always present during operation to prevent
MOSFET failure due to insufficient gate drive.
Topside MOSFET Driver Supply (C B , D B )
External bootstrap capacitors C B connected to the BOOST
1 and BOOST 2 pins supply the gate drive voltages for the
topside MOSFETs. Capacitor C B in the Functional Dia-
gram is charged through diode D B from INTV CC when the
SW1(SW2) pin is low. When one of the topside MOSFETs
is to be turned on, the driver places the C B voltage across
the gate source of the desired MOSFET. This enhances
the MOSFET and turns on the topside switch. The switch
node voltage SW1(SW2) rises to V IN and the BOOST
1(BOOST 2) pin follows. With the topside MOSFET on,
the boost voltage is above the input supply: V BOOST = V IN
+ V INTVCC . The value of the boost capacitor C B needs to
SFB1
R6
R5
LTC1438
LTC1439*
V IN
TGL1
EXTV CC
TGS1*
SW1
BG1
+
C IN
N-CH
V IN
N-CH
N-CH
?
L1
1:1
1N4148
?
V SEC
+
R SENSE
+
1 μ F
V OUT
C OUT
be 100 times that of the total input capacitance of the
topside MOSFET(s). The reverse breakdown on D B must
be greater than V IN(MAX) .
Output Voltage Programming
The LTC1438/LTC1439 have pin selectable output voltage
programming. Controller 1 on the LTC1438-ADJ is a
SGND
PGND
1438 F04a
dedicated adjustable controller. The output voltage is
OPTIONAL EXTV CC
CONNECTION
5V ≤ V SEC ≤ 9V
*TGS1 ONLY AVAILABLE ON THE LTC1439
selected by the V PROG1 (V PROG2 ) pin as follows on all of the
other parts:
Figure 4a. Secondary Output Loop and EXTV CC Connection
V PROG1,2 = 0V
V PROG1,2 = INTV CC
V PROG2 = Open (DC)
V OUT1,2 = 3.3V
V OUT1,2 = 5V
V OUT2 = Adjustable
LTC1438
LTC1439*
V IN
TGL1
TGS1*
EXTV CC
SW1
BG1
PGND
+
C IN
N-CH
V IN
N-CH
N-CH
BAT85
L1
0.22 μ F
VN2222LL
R SENSE
+
+
1 μ F
BAT85
BAT85
V OUT
C OUT
1438 F04b
Except for the LTC1438-ADJ, the top of an internal resis-
tive divider is connected to SENSE – 1 pin in Controller 1.
For fixed output voltage applications the SENSE – 1 pin is
connected to the output voltage as shown in Figure 5a.
When using an external resistive divider for an adjustable
regulator, the V PROG2 pin is left open (V PROG1 is internally
left open on the LTC1438-ADJ) and the V OSENSE2 pin is
connected to the feedback resistors as shown in Figure 5b.
The adjustable controller will force the externally attenu-
*TGS1 ONLY AVAILABLE ON THE LTC1439
ated output voltage to 1.19V.
Figure 4b. Capacitive Charge Pump for EXTV CC
14389fb
16
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| LTC1439CG | 功能描述:IC REG CTRLR BUCK PWM CM 36-SSOP RoHS:否 类别:集成电路 (IC) >> PMIC - 稳压器 - DC DC 切换控制器 系列:- 标准包装:2,000 系列:- PWM 型:电流模式 输出数:1 频率 - 最大:1MHz 占空比:50% 电源电压:9 V ~ 10 V 降压:无 升压:是 回扫:是 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:8-TSSOP（0.173"，4.40mm 宽） 包装:带卷 (TR) |
| LTC1439CG#PBF | 功能描述:IC REG CTRLR BUCK PWM CM 36-SSOP RoHS:是 类别:集成电路 (IC) >> PMIC - 稳压器 - DC DC 切换控制器 系列:- 标准包装:2,000 系列:- PWM 型:电流模式 输出数:1 频率 - 最大:1MHz 占空比:50% 电源电压:9 V ~ 10 V 降压:无 升压:是 回扫:是 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:8-TSSOP（0.173"，4.40mm 宽） 包装:带卷 (TR) |
| LTC1439CG#TR | 功能描述:IC REG CTRLR BUCK PWM CM 36-SSOP RoHS:否 类别:集成电路 (IC) >> PMIC - 稳压器 - DC DC 切换控制器 系列:- 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 |
| LTC1439CG#TRPBF | 功能描述:IC REG CTRLR BUCK PWM CM 36-SSOP RoHS:是 类别:集成电路 (IC) >> PMIC - 稳压器 - DC DC 切换控制器 系列:- 标准包装:4,000 系列:- PWM 型:电压模式 输出数:1 频率 - 最大:1.5MHz 占空比:66.7% 电源电压:4.75 V ~ 5.25 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:40-VFQFN 裸露焊盘 包装:带卷 (TR) |
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