参数资料
| 型号： | SC186ULTRT |
| 厂商： | Semtech |
| 文件页数： | 14/18页 |
| 文件大小： | 0K |
| 描述： | IC REG BUCK SYNC ADJ 4A 16MLPQ |
| 标准包装： | 1 |
| 类型： | 降压（降压） |
| 输出类型： | 可调式 |
| 输出数： | 1 |
| 输出电压： | 0.8 V ~ 3.3 V |
| 输入电压： | 2.9 V ~ 5.5 V |
| PWM 型： | 电压模式 |
| 频率 - 开关： | 1.5MHz |
| 电流 - 输出： | 4A |
| 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： | 16-UFQFN 裸露焊盘 |
| 包装： | 标准包装 |
| 供应商设备封装： | 16-MLPQ-UT（3x3） |
| 其它名称： | SC186ULDKR |
SC186
Applications Information (continued)
CTL0
CTL1
load resistance. When the load presented falls below the
current limit holding level, the output will charge to the
upper PSAVE voltage threshold and return to normal
operation. The SC186 is capable of sustaining an indefi-
nite short circuit without damage. During the soft start, if
current limit has occurred before the SS voltage has
reached 400mV, the part enters foldback current limit
mode. Foldback current limit mode will be disabled during
soft-start after the SS voltage is higher than 400mV.
V IN
C IN
22μF
R PGOOD
100k Ω
Enable
R AVIN -1 Ω
C AVIN
0.1μF
LX
PVIN
SC186
AVIN
VOUT
PGOOD
SSA
PGND
CTL2 AGND
L
R FB1
R FB2
10k Ω
V OUT
C FF C OUT
R FB1 = (V OUT -1)
x R FB2
for CTL X = 0010
(1.0V)
C SS
10nF
CTL3
Over-Voltage Protection
In the event of a 15% over-voltage on the output, the
R FB 2
V OUT V OSTD
V OSTD
V OUT
0 . 5
V OSTD
R FB 1 [ k ]
V OUT
V OSTD
V OSTD
C FF [ nF ] 2 . 5 ( )
PWMdriveisdisabledwiththeLXpinfloating. Switching
does not resume until the output voltage falls below the
nominal V OUT regulation voltage.
Programmable Output Voltage
The SC186 has fifteen pre-determined output voltage
values which can be individually selected by program-
ming the CTL input pins (see Table 1 — Output Voltage
Settings). Each CTL pin has an active 500kΩ internal pull-
down resistor. The 500kΩ resistor is switched in circuit
whenever the CTL input voltage is below the input thresh-
old, or when the part is in under voltage lockout. It is
recommended to tie all high CTL pins together and use an
external pull-up resistor to AVIN if there is no enable signal
or if the enable input is an open drain/collector 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 program-
mable output voltages as this would disable the device.
SC186 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
adjustable output voltage option from the standard 1.0V
with CTLx=[0010], is shown in Figure 2. 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 using the next equation.
RFB2 needs to be low enough in value for the current
through the resistor chain to be at least 20μA in order to
ignore the VOUT pin current.
Figure 2 — Output Voltage Programming
R FB 1
where V OSTD is the pre-determined output voltage via the
CTL pins.
C FF is needed to maintain good transient response perfor-
mance. The correct value of C FF can be found using the
following equation.
2
0 . 5
To simplify the design, it is recommended to program the
desired output voltage from a standard 1.0V as shown in
Figure 2 with a proper 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 conform
to the previous equations.
Shut Down
When all CTL pins are low, the device will run in shutdown
mode, drawing less than 1μA from the input power supply.
The internal switches and band-gap voltage will be imme-
diately turned off.
Thermal Shutdown
The device has a thermal shutdown feature to protect the
SC186 if the junction temperature exceeds 160°C. During
thermal shutdown, the on-chip power devices are dis-
abled, floating the LX output. When the temperature
drops by 10°C, it will initiate a soft start cycle to resume
normal operation.
14
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相关代理商/技术参数 |
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| SC187 | 制造商:SEMTECH 制造商全称:Semtech Corporation 功能描述:4A, 2.2MHz Synchronous Step-Down Regulator with 15 Preset Output Voltages |
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