参数资料
| 型号： | SC900AMLTRT |
| 厂商： | Semtech |
| 文件页数： | 11/23页 |
| 文件大小： | 0K |
| 描述： | IC REG LDO ADJ .2A/.15A 20-MLPQ |
| 标准包装： | 1 |
| 稳压器拓扑结构： | 正，可调式 |
| 输出电压： | 1.45 V ~ 3 V，1.75 V ~ 3.3 V |
| 输入电压： | 2.7 V ~ 5.5 V |
| 电压 - 压降（标准）： | 0.2V @ 200mA，0.15V @ 150mA |
| 稳压器数量： | 5 |
| 电流 - 输出： | 200mA（最小），150mA（最小），150mA（最小），150mA（最小），150mA（最小） |
| 电流 - 限制（最小）： | 250mA |
| 工作温度： | -40°C ~ 85°C |
| 安装类型： | 表面贴装 |
| 封装/外壳： | 20-VFQFN 裸露焊盘 |
| 供应商设备封装： | 20-MLPQ（4x4） |
| 包装： | 剪切带 (CT) |
| 产品目录页面： | 1358 (CN2011-ZH PDF) |
| 其它名称： | SC900AMLCT |
SC900A
POWER MANAGEMENT
Applications Information (Cont.)
Active Shutdown
The shutdown control bits determine how the on-chip ac-
tive shutdown switches behave. Each LDO register uses
bit 5 of the LDO output voltage data byte to control the
shutdown behavior. When the active shutdown bit is en-
abled (set to 1), the capacitance on the LDO output will be
discharged by an on-chip FET after the LDO is disabled.
When the active shutdown bit is disabled (set to 0), the
output capacitance on the LDO output is discharged by
the load. The default active shutdown state for all LDOs
is on.
ON/OFF Control Register
Each individual LDO may be turned on or off by accessing
the ON/OFF control register. LDOs are turned on by set-
ting their respective on/off bit to 1. Likewise, they can be
turned off by setting the on/off bit to 0. This allows for
on/off control with a single write command. If the enable
(EN) pin is high and data is written to the LDO voltage reg-
isters, the LDO outputs will go to the voltage prescribed by
the Output Voltage Code bits (0-4). Data will not be lost
when toggling the on/off bit from 0 to 1. However, if the
EN pin is forced low, all circuitry in the device is disabled.
All programmed information is lost when the enable bit is
subsequently pulled high.
VASEL Pin
The VASEL pin sets the default voltage of LDO A, the core
supply. When this pin is set to V IN , the default voltage is
2.80V. When this pin is set to GND, the default voltage is
1.80V. The voltage can be changed from its default state
after start up by writing to the LDO voltage code register.
Device Addressing
Following a start condition, the master must output the
address of the slave it is accessing. The most signi ? cant
six bits of the slave are the device type identi ? er (ID). For
the SC900A this is ? xed at 000100[B]. The next signi ? -
cant bit addresses a particular device. A system can have
up to two SC900A devices on the bus. The two addresses
are de ? ned by the state of the A0 input (see Figure 1).
When the A0 pin is tied to GND, device 1 has an address
of 0 and the combination of device type ID and address is
0x08H. When the A0 pin is tied to V IN , device 2 has and
address of 1 and the combination of device type ID and
address is 0x09H.
The last bit of the slave address de ? nes the operation to
be performed. When set to a one a read operation is se-
lected; when set to a zero a write operation is selected.
Following a start condition, the SC900A monitors the SDA
line comparing the slave address being transmitted with
its slave address (device type ID and state of A0 input).
Upon a correct compare the SC900A outputs an acknowl-
edge on the SDA line. Depending on the state of the R/W
bit, the SC900A will execute a read or write operation.
Protection Circuitry
The SC900A provides protection circuitry that prevents
the device from operating in an unspeci ? ed state. These
include Under Voltage Lockout Protection, Over-tempera-
ture Protection and Short-circuit Protection.
Under Voltage Lockout
The SC900A provides an Under Voltage Lockout (UVLO)
circuit to protect the device from operating in an unknown
state if the input voltage supply is too low. When the bat-
tery voltage drops below the UVLO threshold, the LDOs
are disabled. As the battery voltage increases above the
hysteresis level, the LDOs are re-enabled into their previ-
ous states, provided ENABLE has remained high. If EN-
ABLE goes low, the SC900A will shut down.
Over Temperature Protection
The SC900A provides an internal Over-temperature (OT)
protection circuit that monitors the internal junction tem-
perature. When the temperature exceeds the OT thresh-
old, the OT protection disables all the LDO outputs. As
the junction temperature drops below the hysteresis level
the OT protection re-enables all the LDOs in their previous
states, provided ENABLE has remained high. If ENABLE
goes low, the SC900A will shut down.
0
DEVICE TYPE IDENTIFIER
0 0 1 0
0
DEVICE ADDRESS
Pin A0 to GND = 0
Pin A0 to VIN = 1
R/W
X
Short-Circuit Protection
Each LDO output has short-circuit protection. If a short is
applied to any output, the output voltage will drop and the
Figure 1 - Slave Address Structure
output current will be limited to the short circuit current
until the short is removed.
? 2005 Semtech Corp.
11
www.semtech.com
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