- 您现在的位置：买卖IC网 > PDF目录44995 > LTC3890EGN-1#PBF (LINEAR TECHNOLOGY CORP) SWITCHING CONTROLLER, PDSO28 PDF资料下载
参数资料
| 型号： | LTC3890EGN-1#PBF |
| 厂商： | LINEAR TECHNOLOGY CORP |
| 元件分类： | 稳压器 |
| 英文描述： | SWITCHING CONTROLLER, PDSO28 |
| 封装： | LEAD FREE, PLASTIC, SSOP-28 |
| 文件页数： | 5/36页 |
| 文件大小： | 498K |
| 代理商： | LTC3890EGN-1#PBF |
第1页第2页第3页第4页当前第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页第33页第34页第35页第36页
LTC3890-1
13
38901f
OPERATION (Refer to the Functional Diagram)
If the PLLIN/MODE pin is not being driven by an external
clock source, the FREQ pin can be tied to SGND, tied to
INTVCC or programmed through an external resistor.
Tying FREQ to SGND selects 350kHz while tying FREQ
to INTVCC selects 535kHz. Placing a resistor between
FREQ and SGND allows the frequency to be programmed
between 50kHz and 900kHz, as shown in Figure 10.
A phase-locked loop (PLL) is available on the LTC3890-1
to synchronize the internal oscillator to an external clock
source that is connected to the PLLIN/MODE pin. The
LTC3890-1’s phase detector adjusts the voltage (through
an internal lowpass lter) of the VCO input to align the
turn-on of controller 1’s external top MOSFET to the ris-
ing edge of the synchronizing signal. Thus, the turn-on of
controller 2’s external top MOSFET is 180 degrees out of
phase to the rising edge of the external clock source.
The VCO input voltage is prebiased to the operating fre-
quency set by the FREQ pin before the external clock is
applied. A resistor connected between the FREQ pin and
SGND can prebias VCO’s input voltage to the desired
frequency. If prebiased near the external clock frequency,
the PLL loop only needs to make slight changes to the
VCO input in order to synchronize the rising edge of the
external clock’s to the rising edge of TG1. The ability to
prebias the loop lter allows the PLL to lock-in rapidly
without deviating far from the desired frequency.
The typical capture range of the phase-locked loop is
from approximately 55kHz to 1MHz, with a guarantee
to be between 75kHz and 850kHz. In other words, the
LTC3890-1’s PLL is guaranteed to lock to an external clock
source whose frequency is between 75kHz and 850kHz.
The typical input clock thresholds on the PLLIN/MODE
pin are 1.6V (rising) and 1.2V (falling).
Output Overvoltage Protection
An overvoltage comparator guards against transient over-
shoots as well as other more serious conditions that may
overvoltage the output. When the VFB pin rises by more
than 10% above its regulation point of 0.800V, the top
MOSFET is turned off and the bottom MOSFET is turned
on until the overvoltage condition is cleared.
Power Good (PGOOD1 Pin)
The PGOOD1 pin is connected to an open drain of an internal
N-channel MOSFET. The MOSFET turns on and pulls the
PGOOD1 pin low when the corresponding VFB1 pin volt-
age is not within ±10% of the 0.8V reference voltage. The
PGOOD1 pin is also pulled low when the corresponding
RUN1 pin is low (shut down). When the VFB1 pin voltage
is within the ±10% requirement, the MOSFET is turned
off and the pin is allowed to be pulled up by an external
resistor to a source no greater than 6V.
Foldback Current
When the output voltage falls to less than 70% of its
nominal level, foldback current limiting is activated, pro-
gressively lowering the peak current limit in proportion to
the severity of the overcurrent or short-circuit condition.
Foldback current limiting is disabled during the soft-start
interval (as long as the VFB voltage is keeping up with the
TRACK/SS voltage).
Theory and Benets of 2-Phase Operation
Why the need for 2-phase operation? Up until the 2-phase
family, constant-frequency dual switching regulators
operated both channels in phase (i.e., single phase
operation). This means that both switches turned on at
the same time, causing current pulses of up to twice the
amplitude of those for one regulator to be drawn from the
input capacitor and battery. These large amplitude current
pulses increased the total RMS current owing from the
input capacitor, requiring the use of more expensive input
capacitors and increasing both EMI and losses in the input
capacitor and battery.
With 2-phase operation, the two channels of the dual
switching regulator are operated 180 degrees out of phase.
This effectively interleaves the current pulses drawn by the
switches, greatly reducing the overlap time where they add
相关PDF资料 |
PDF描述 |
|---|---|
| LTC3890IGN-1#TRPBF | SWITCHING CONTROLLER, PDSO28 |
| LTC3890IGN-1#PBF | SWITCHING CONTROLLER, PDSO28 |
| LTC3890MPUH#TRPBF | DUAL SWITCHING CONTROLLER, 585 kHz SWITCHING FREQ-MAX, PQCC32 |
| LTC3890EUH#PBF | DUAL SWITCHING CONTROLLER, 585 kHz SWITCHING FREQ-MAX, PQCC32 |
| LTC3890IUH#TRPBF | DUAL SWITCHING CONTROLLER, 585 kHz SWITCHING FREQ-MAX, PQCC32 |
相关代理商/技术参数 |
参数描述 |
|---|---|
| LTC3890EGN-3#PBF | 制造商:Linear Technology 功能描述:IC REG CTRLR BUCK PWM CM 28SSOP 制造商:Linear Technology 功能描述:DC-DC CONTROLLER BUCK 900KHZ 制造商:Linear Technology 功能描述:DC-DC CONTROLLER, BUCK, 900KHZ, SSOP-28 制造商:Linear Technology 功能描述:DC-DC CONTROLLER, BUCK, 900KHZ, SSOP-28; Primary Input Voltage:60V; No. of Outputs:2; No. of Pins:28; Operating Temperature Min:-40C; Operating Temperature Max:125C; Operating Temperature Range:-40C to +125C ;RoHS Compliant: Yes |
| LTC3890EGN-3#TRPBF | 制造商:Linear Technology 功能描述:IC REG CTRLR BUCK PWM CM 28SSOP |
| LTC3890EUH#PBF | 功能描述:IC REG CTRLR BUCK PWM CM 32-QFN RoHS:是 类别:集成电路 (IC) >> PMIC - 稳压器 - DC DC 切换控制器 系列:PolyPhase® 特色产品:LM3753/54 Scalable 2-Phase Synchronous Buck Controllers 标准包装:1 系列:PowerWise® PWM 型:电压模式 输出数:1 频率 - 最大:1MHz 占空比:81% 电源电压:4.5 V ~ 18 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:-5°C ~ 125°C 封装/外壳:32-WFQFN 裸露焊盘 包装:Digi-Reel® 产品目录页面:1303 (CN2011-ZH PDF) 其它名称:LM3754SQDKR |
| LTC3890EUH#TRPBF | 功能描述:IC REG CTRLR BUCK PWM CM 32-QFN 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 |
| LTC3890EUH-2#PBF | 制造商:Linear Technology 功能描述:DC DC Cntrlr Dual-OUT Sync Step Down 4V to 60V Input 32-Pin QFN EP 制造商:Linear Technology 功能描述:DP-SWREG/Controller, 60V, Low IQ, Dual Output Synchronous Step-Down Controller |
发布紧急采购，3分钟左右您将得到回复。