- 您现在的位置：买卖IC网 > PDF目录15265 > LTC1873EG#TRPBF (Linear Technology)IC REG CTRLR BUCK PWM VM 28-SSOP PDF资料下载
参数资料
| 型号： | LTC1873EG#TRPBF |
| 厂商： | Linear Technology |
| 文件页数： | 10/32页 |
| 文件大小： | 0K |
| 描述： | IC REG CTRLR BUCK PWM VM 28-SSOP |
| 标准包装： | 2,000 |
| PWM 型： | 电压模式 |
| 输出数： | 2 |
| 频率 - 最大： | 750kHz |
| 占空比： | 93% |
| 电源电压： | 3 V ~ 7 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： | 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页当前第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
LTC1873
APPLICATIO S I FOR ATIO
Switching Architecture
Each half of the LTC1873 is designed to operate as a
synchronous buck converter (Figure 1). Each channel
includes two high power MOSFET gate drivers to control
external N-channel MOSFETs QT and QB. These drivers
have 0.5 ? output impedances and can carry well over an
amp of continuous current with peak currents up to 5A to
slew large MOSFET gates quickly. The external MOSFETs
are connected with the drain of QT attached to the input
supply and the source of QT at the switching node SW. QB
is the synchronous rectifier with its drain at SW and its
source at PGND. SW is connected to one end of the
inductor, with the other end connected to V OUT . The output
capacitor is connected from V OUT to PGND.
When a switching cycle begins, QB is turned off and QT is
turned on. SW rises almost immediately to V IN and the
inductor current begins to increase. When the PWM pulse
finishes, QT turns off and one nonoverlap interval later, QB
turns on. Now SW drops to PGND and the inductor current
decreases. The cycle repeats with the next tick of the
master clock. The percentage of time spent in each mode
is controlled by the duty cycle of the PWM signal, which in
turn is controlled by the feedback amplifier. The master
clock runs at a 550kHz rate and turns QT once every 1.8 μ s.
In a typical application with a 5V input and a 1.5V output,
the duty cycle will be set at 1.5/5 × 100% or 30% by the
feedback loop. This will give roughly a 540ns on-time for
QT and a 1.26 μ s on-time for QB.
This constant frequency operation brings with it a couple
of benefits. Inductor and capacitor values can be chosen
with a precise operating frequency in mind and the feed-
back loop components can be similarly tightly specified.
Noise generated by the circuit will always be in a known
frequency band with the 550kHz frequency designed to
leave the 455kHz IF band free of interference. Subharmonic
oscillation and slope compensation, common headaches
with constant frequency current mode switchers, are
absent in voltage mode designs like the LTC1873.
During the time that QT is on, its source (the SW pin) is at
V IN . V IN is also the power supply for the LTC1873. How-
ever, QT requires V IN + V GS(ON) at its gate to achieve
minimum R ON . This presents a problem for the LTC1873—
it needs to generate a gate drive signal at TG higher than
its highest supply voltage. To accomplish this, the TG
driver runs from floating supplies, with its negative supply
attached to SW and its power supply at BOOST. This allows
it to slew up and down with the source of QT. In combination
with a simple external charge pump (Figure 2), this allows
the LTC1873 to completely enhance the gate of QT without
requiring an additional, higher supply voltage.
The two channels of the LTC1873 run from a common
clock, with the phasing chosen to be 180 ° from side 1 to
side 2. This has the effect of doubling the frequency of the
switching pulses seen by the input bypass capacitor,
significantly lowering the RMS current seen by the capaci-
tor and reducing the value required (see the 2-Phase
section).
Feedback Amplifier
Each side of the LTC1873 senses the output voltage at
V OUT with an internal feedback op amp (see Block Dia-
gram). This is a real op amp with a low impedance output,
85dB open-loop gain and 25MHz gain-bandwidth product.
The positive input is connected internally to an 800mV
reference, while the negative input is connected to the FB
V IN
V IN
PV CC
BOOST
D CP
+
C IN
PGND
TG
1/2
LTC1873 SW
BG
QT
QB
L EXT
+
+
C IN
C OUT
V OUT
LTC1873
PGND
TG
SW
BG
C CP
1 μ F
QT
QB
L EXT
+
V OUT
C OUT
10
1873 F01
Figure 1. Synchronous Buck Architecture
Figure 2. Floating TG Driver Supply
1873 F02
相关PDF资料 |
PDF描述 |
|---|---|
| H2AXT-10112-W4-ND | JUMPER-H1502TR/A2015W/X 12" |
| LTC1159CG-5 | IC REG CTRLR BUCK PWM CM 20-SSOP |
| LTC1159CG-3.3#PBF | IC REG CTRLR BUCK PWM CM 20-SSOP |
| LTC1159CG-3.3 | IC REG CTRLR BUCK PWM CM 20-SSOP |
| H2AXT-10112-V4-ND | JUMPER-H1502TR/A2015V/X 12" |
相关代理商/技术参数 |
参数描述 |
|---|---|
| LTC1874EGN | 功能描述:IC REG CTRLR BUCK PWM CM 16-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:2,500 系列:- PWM 型:电流模式 输出数:1 频率 - 最大:500kHz 占空比:96% 电源电压:4 V ~ 36 V 降压:无 升压:是 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:24-WQFN 裸露焊盘 包装:带卷 (TR) |
| LTC1874EGN#PBF | 功能描述:IC REG CTRLR BUCK PWM CM 16-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:2,500 系列:- PWM 型:电流模式 输出数:1 频率 - 最大:500kHz 占空比:96% 电源电压:4 V ~ 36 V 降压:无 升压:是 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:24-WQFN 裸露焊盘 包装:带卷 (TR) |
| LTC1874EGN#TR | 功能描述:IC REG CTRLR BUCK PWM CM 16-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:2,500 系列:- PWM 型:电流模式 输出数:1 频率 - 最大:500kHz 占空比:96% 电源电压:4 V ~ 36 V 降压:无 升压:是 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:24-WQFN 裸露焊盘 包装:带卷 (TR) |
| LTC1874EGN#TRPBF | 功能描述:IC REG CTRLR BUCK PWM CM 16-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:2,500 系列:- PWM 型:电流模式 输出数:1 频率 - 最大:500kHz 占空比:96% 电源电压:4 V ~ 36 V 降压:无 升压:是 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:24-WQFN 裸露焊盘 包装:带卷 (TR) |
| LTC1875EGN | 功能描述:IC REG BUCK SYNC ADJ 1.5A 16SSOP RoHS:否 类别:集成电路 (IC) >> PMIC - 稳压器 - DC DC 开关稳压器 系列:- 标准包装:2,500 系列:- 类型:降压（降压） 输出类型:固定 输出数:1 输出电压:1.2V，1.5V，1.8V，2.5V 输入电压:2.7 V ~ 20 V PWM 型:- 频率 - 开关:- 电流 - 输出:50mA 同步整流器:是 工作温度:-40°C ~ 125°C 安装类型:表面贴装 封装/外壳:10-TFSOP，10-MSOP（0.118"，3.00mm 宽）裸露焊盘 包装:带卷 (TR) 供应商设备封装:10-MSOP 裸露焊盘 |
发布紧急采购，3分钟左右您将得到回复。