- 您现在的位置：买卖IC网 > PDF目录15234 > LTC1438XCG#TR (Linear Technology)IC REG CTRLR BUCK PWM CM 28-SSOP PDF资料下载
参数资料
| 型号： | LTC1438XCG#TR |
| 厂商： | Linear Technology |
| 文件页数： | 19/32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) |
第1页第2页第3页第4页第5页第6页第7页第8页第9页第10页第11页第12页第13页第14页第15页第16页第17页第18页当前第19页第20页第21页第22页第23页第24页第25页第26页第27页第28页第29页第30页第31页第32页
LTC1438/LTC1439
APPLICATIO N S I N FOR M ATIO N
C LP holds the voltage. The LTC1439 PLLIN pin must be
V IN
driven from a low impedance such as a logic gate located
close to the pin. Any external attenuator used needs to be
R4
LBI
–
LTC1438/LTC1439
LBO
referenced to SGND.
R3
+
The loop filter components C LP , R LP smooth out the
SGND
1.19V REFERENCE
1438 F10
current pulses from the phase detector and provide a
stable input to the voltage-controlled oscillator. The filter
components C LP and R LP determine how fast the loop
acquires lock. Typically, R LP =10k and C LP is 0.01 μ F to 0.1 μ F.
The low side of the filter needs to be connected to SGND.
The PLL LPF pin can be driven with external logic to obtain
a 1:1.9 frequency shift. The circuit shown in Figure 9 will
provide a frequency shift from f O to 1.9f O as the voltage on
V PLLLPF increases from OV to 2.4V. Do not exceed 2.4V on
V PLLLPF .
Figure 10. Low-Battery Comparator
SFB1 Pin Operation
When the SFB1 pin drops below its ground referenced
1.19V threshold, continuous mode operation is forced. In
continuous mode, the large N-channel main and synchro-
nous switches are used regardless of the load on the main
output.
In addition to providing a logic input to force continuous
synchronous operation, the SFB1 pin provides a means to
2.4V
MAX
3.3V OR 5V
regulate a flyback winding output. The use of a synchro-
nous switch removes the requirement that power must be
PLL LPF
18k
LTC1435 ? F09
Figure 9. Directly Driving PLL LPF Pin
Low-Battery Comparator
The LTC1438/LTC1439 have an on-chip low-battery com-
parator which can be used to sense a low-battery condi-
tion when implemented as shown in Figure 10. The resistor
divider R3/R4 sets the comparator trip point as follows:
drawn from the inductor primary in order to extract power
from the auxiliary winding. With the loop in continuous
mode, the auxiliary output may be loaded without regard
to the primary output load. The SFB1 pin provides a way
to force continuous synchronous operation as needed by
the flyback winding.
The secondary output voltage is set by the turns ratio of
the transformer in conjunction with a pair of external
resistors returned to the SFB1 pin as shown in Figure 4a.
The secondary regulated voltage V SEC in Figure 4a is given
by:
V LBITRIP = 1 . 19 V ? 1 +
R 3 ?
V SEC ≈ ( N + 1 ) V OUT > 1 . 19 V ? 1 +
R 5 ?
?
?
R 4 ?
?
?
?
R 6 ?
?
The divided down voltage at the negative (–) input to the
comparator is compared to an internal 1.19V reference. A
20mV hysteresis is built in to assure rapid switching. The
output is an open drain MOSFET and requires a pull-up
resistor. This comparator is not active when both the
RUN/SS1 and RUN/SS2 pins are low. Refer to the LTC1538/
LTC1539 for a comparator which is active during shutdown.
The low side of the resistive divider needs to be connected to
where N is the turns ratio of the transformer, and V OUT is
the main output voltage sensed by Sense – 1.
Auxiliary Regulator/Comparator
The auxiliary regulator/comparator can be used as a
comparator or low dropout regulator (by adding an exter-
nal PNP pass device).
SGND.
14389fb
19
相关PDF资料 |
PDF描述 |
|---|---|
| VE-J7N-EY-F4 | CONVERTER MOD DC/DC 18.5V 50W |
| LTC1438XCG#PBF | IC REG CTRLR BUCK PWM CM 28-SSOP |
| VI-2TN-EW-F2 | CONVERTER MOD DC/DC 18.5V 100W |
| H2ABT-10106-B8-ND | JUMPER-H1502TR/A3048B/H1500TR 6" |
| SLPX392M050C3P3 | CAP ALUM 3900UF 50V 20% SNAP |
相关代理商/技术参数 |
参数描述 |
|---|---|
| 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) |
| LTC1439CGW | 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 |
发布紧急采购，3分钟左右您将得到回复。