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| 型号： | LTC1873EG#TRPBF |
| 厂商： | Linear Technology |
| 文件页数： | 9/32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) |
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LTC1873
APPLICATIO S I FOR ATIO
factor of 3.75. The reduced input ripple voltage also means
less power is lost in the input power path, which could
include batteries, switches, trace/connector resistances
and protection circuitry. Improvements in both conducted
and radiated EMI also directly accrue as a result of the
reduced RMS input current and voltage.
The voltage mode feedback loop and MOSFET V DS current
limit sensing remove the need for an external current
sense resistor, eliminating an external component and a
source of power loss in the high current path. Properly
designed circuits using low gate charge MOSFETs are
capable of efficiencies exceeding 90% over a wide range
of output voltages.
Small Footprint
The LTC1873 operates at a 550kHz switching frequency,
allowing it to use low value inductors without generating
excessive ripple currents. Because the inductor stores
less energy per cycle, the physical size of the inductor can
be reduced without risking core saturation, saving PCB
board space. The high operating frequency also means
less energy is stored in the output capacitors between
cycles, minimizing their required value and size. The
remaining components, including the SSOP-28 LTC1873,
are tiny, allowing an entire dual-output LTC1873 circuit to
be constructed in 1.5in 2 of PCB space. Further, this space
is generally located right next to the microprocessor or in
some similarly congested area, where PCB real estate is at
a premium.
Fast Transient Response
The LTC1873 uses a fast 25MHz GBW op amp as an error
amplifier. This allows the compensation network to be
designed with several poles and zeros in a more flexible
configuration than with a typical g m feedback amplifier.
The high bandwidth of the amplifier, coupled with the high
switching frequency and the low values of the external
inductor and output capacitor, allow very high loop cross-
over frequencies. The low inductor value is the other half
of the equation—with a typical value on the order of 1 μ H,
the inductor allows very fast di/dt slew rates. The result is
superior transient response compared with conventional
solutions.
High Efficiency
The LTC1873 uses a synchronous step-down (buck)
architecture, with two external N-channel MOSFETs per
output. A floating topside driver and a simple external
VID Programming
The LTC1873 includes an onboard feedback network that
programs the output voltage at side 1 in accordance with
the Intel Desktop VID specification (Table 1). The network
includes a 20k resistor (R1) connected from SENSE to
FB1, and a variable value resistor (R B ) from FB1 to SGND,
with the value set by the digital code present at the VID0:4
pins. SENSE should be connected to V OUT1 to allow the
network to monitor the output voltage. No additional
feedback components are required to set the output volt-
age at controller 1, although loop compensation compo-
nents are still required. Each VIDn pin includes an internal
40k pull-up resistor, allowing it to float high if left uncon-
nected. The pull-up resistors are connected to V CC through
diodes (see Block Diagram), allowing the VIDn pins to be
pulled above V CC without damage.
Note that code 11111, defined by Intel to indicate “no CPU
present,” does generate an output voltage at V OUT1 (2.00V).
Note also that controller 2 on the LTC1873 is not con-
nected to the VID circuitry, and works independently from
controller 1.
ARCHITECTURE DETAILS
The LTC1873 dual switching regulator controller includes
two independent regulator channels. The two sides of the
chip and their corresponding external components act
independently of each other with the exception of the
common input bypass capacitor, the VID circuitry at side
1, and the FCB and FAULT pins, which affect both chan-
nels. In the following discussions, when a pin is referred
to without mentioning which side is involved, that discus-
sion applies equally to both sides.
charge pump provide full gate drive to the upper MOSFET.
9
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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 |
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