参数资料
| 型号： | SC283WLTRT |
| 厂商： | Semtech |
| 文件页数： | 12/20页 |
| 文件大小： | 0K |
| 描述： | IC REG BUCK SYNC ADJ 1.8A 18MLPQ |
| 标准包装： | 1 |
| 类型： | 降压（降压） |
| 输出类型： | 可调式 |
| 输出数： | 2 |
| 输出电压： | 0.8 V ~ 3.3 V |
| 输入电压： | 2.9 V ~ 5.5 V |
| 频率 - 开关： | 2.5MHz |
| 电流 - 输出： | 1.8A |
| 同步整流器： | 是 |
| 工作温度： | -40°C ~ 85°C |
| 安装类型： | 表面贴装 |
| 封装/外壳： | 18-WFQFN 裸露焊盘 |
| 包装： | 标准包装 |
| 供应商设备封装： | 18-MLPQ-W（2x3） |
| 其它名称： | SC283WLDKR |
SC283
Applications Information
Detailed Description
The SC283 is a two channel synchronous step-down
converter. Both channels on this device are designed to
enough in value for the current through the resistor chain
to be at least 20μA in order to ignore the VOUT pin current.
operate in fixed-frequency PWM mode at 2.5MHz and
provide the same current capacity of up to 1.8A. The
R FB 1 =
V OUT ? V OSTD
V OSTD
? R FB 2
(1)
switching frequency is chosen to minimize the size of the
external inductor and capacitors while maintaining high
efficiency. Both channels of SC283 are independent.
Operation
During normal operation, the PMOS MOSFET is activated
on each rising edge of the internal oscillator. The voltage
feedback loop uses an internal feedback resistor divider.
where V OSTD is the pre-determined output voltage via the
CTL pins.
C FF is needed to maintain good transient response
performance. The correct value of C FF can be found using
Equation 2.
The period is set by the internal oscillator. The device
has an internal synchronous NMOS rectifier and does
C FF [ nF ] = 2 . 5 ×
( V OUT ? 0 . 5 ) 2
R FB 1 [ k ? ] ? ( V OUT ? V OSTD )
× (
V OSTD
V OSTD ? 0 . 5
)
(2)
not require a Schottky diode on the LX pin. The device
operates as a buck converter in PWM mode with a fixed
frequency of 2.5MHz.
Programmable Output Voltage
Both channels on SC283 have fifteen pre-determined
output voltage values which can be individually selected
by programming the CTL input pins (see Table 1 — Output
To simplify the design, it is recommended to program the
desired output voltage from a standard 1.0V as shown in
Figure 1 with the correct C FF calculated from Equation 2.
For programming the output voltage from other standard
voltages, R FB1 , R FB2 and C FF need to be adjusted to meet
Equations 1 and 2.
Voltage Settings). Each CTL pin has an active 1 MΩ
internal pulldown resistor. The 1MΩ resistor is switched in
circuit whenever the CTL input voltage is below the input
threshold, or when the part is in undervoltage lockout.
V IN
C IN_
10μF
VIN LX_
SC283
(Channel A or B)
VOUT_
R FB1
L_
C FF
C OUT_
V OUT_
It is recommended to tie all high CTL pins together and
CTL0_
R FB2
R FB 1 = ( V OUT ? 1 ) × R FB 2
use an external pull-up resistor to VIN if there is no enable
signal, or if the enable input is an open drain/collector
Enable
CTL1_
CTL2_
CTL3_
GND
for CTLx= 0010 (1.0V)
signal. The CTL pins may be driven by a microprocessor to
allow dynamic voltage adjustment for systems that reduce
the supply voltage when entering sleep states. Avoid
all zeros being present on the CTL pins when changing
programmable output voltages as this would disable the
device.
SC283 is also capable of regulating a different (higher)
output voltage, which is not shown in the Table 1, via an
external resistor divider. There will be a typical 2μA current
flowing into the VOUT pin. The typical schematic for an ad-
justable output voltage option from the standard 1.0V with
CTLx=[0010], is shown in Figure 1. RFB1 and RFB2 are used
to adjust the desired output voltage. If the RFB2 current is
such that the 2μA VOUT pin current can be ignored, then
RFB1 can be found by Equation 1. RFB2 needs to be low
Figure 1 — Typical Schematic for Adjusting the
Output Voltage Up from an Output Voltage of 1.0V
(CTLx=[0010])
Maximum Power Dissipation
Each channel of SC283 has its own Θ JA of 65°C/W when
only one channel is in operation. Since both channels are
within same package, there is about 50% heat which will be
transferred to the adjacent channel. The equivalent total
thermal impedence will be higher when the neighboring
channel is also in operation. To guarantee an operating
junction temperature of less than 125°C, Figure 2 shows
the maximum allowable power loss of each channel. The
curve is based upon the junction temperature of either
channel reaching a maximum of 125°C. Each channel of
SC283 can support up to 1.8A load current. Figures 3a
? 2010 Semtech Corp.
12
www.semtech.com
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相关代理商/技术参数 |
参数描述 |
|---|---|
| SC284 | 制造商:SEMTECH 制造商全称:Semtech Corporation 功能描述:Dual Channel 2.5MHz, 1.8A Synchronous Step-Down Regulator |
| SC284ULTRT | 制造商:Semtech Corporation 功能描述:Conv DC-DC Dual Step Down 2.9V to 5.5V 20-Pin MLPQ EP T/R |
| SC28-6 | 制造商:Thomas & Betts 功能描述:IDENTIFICATION TAGS |
| SC286ULTRT | 功能描述:IC REG BUCK SYNC ADJ 4A 28MLPQ RoHS:是 类别:集成电路 (IC) >> PMIC - 稳压器 - DC DC 开关稳压器 系列:- 标准包装:1,000 系列:- 类型:降压（降压） 输出类型:可调式 输出数:1 输出电压:0.6 V ~ 4.5 V 输入电压:3 V ~ 5.5 V PWM 型:电流模式 频率 - 开关:3MHz 电流 - 输出:1.5A 同步整流器:无 工作温度:-40°C ~ 125°C 安装类型:表面贴装 封装/外壳:6-WDFN 裸露焊盘 包装:带卷 (TR) 供应商设备封装:6-LLP-EP（3x3） 产品目录页面:1300 (CN2011-ZH PDF) 其它名称:LM2831ZSDLM2831ZSDTR |
| SC28829PK04 | 制造商:Rochester Electronics LLC 功能描述:- Bulk |
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