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参数资料
| 型号： | LTC3456 |
| 厂商： | Linear Technology Corporation |
| 元件分类： | 基准电压源/电流源 |
| 英文描述： | 2-Cell, Multi-Output DC/DC Converter with USB Power Manager |
| 中文描述： | 2节电池，多输出DC / DC转换器与USB电源管理器 |
| 文件页数： | 17/28页 |
| 文件大小： | 358K |
| 代理商： | LTC3456 |
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17
LTC3456
3456f
OPERATIOU
The LTC3456 incorporates additional features like output
short-circuit protection and thermal regulation. When the
core regulator output (V
CORE
) is shorted to ground, the
LTC3456’s unique control scheme prevents inductor cur-
rent runaway.
Dropout Operation
The LTC3456 is capable of operating at 100% duty cycle
when powered from the battery. If the input supply voltage
decreases to a value close to the output voltage, the core
regulator will run at 100% duty cycle. The output voltage
is then determined by the input voltage minus the voltage
drop across the PMOS switch and the inductor. When
running off the USB or the AC adapter, this situation never
arises (there is plenty of voltage headroom).
When the LTC3456 operates with low input supply volt-
age, say 1.8V (fully discharged two AA cells) the maximum
allowable output current gets reduced. Figure 7 shows the
reduction in the maximum output current as a function of
input voltage for various output voltages.
to power some of the internal circuitry of the IC. Connect
a 1
μ
F bypass capacitor from this pin to ground. It can be
used to supply a maximum of 1mA output load.
The V
MAX
output voltage stays alive even when the IC is in
shutdown. During shutdown, the V
MAX
output will be the
highest of V
BATT
, V
EXT
and USB voltages. V
MAX
output can
be used to supply power to a critical block like the real-time
clock, which needs to stay alive even during shutdown.
POWER SEQUENCING
Power On/Off
The LTC3456 can turned on in two different ways:
Pulling the PWRKEY pin low
Pulling the PWRON pin high
Pulling the PWRKEY pin low is usually the first step in
turning on the LTC3456. When PWRKEY is pulled low, it
powers on the bandgap reference. Onboard voltage moni-
tors check the status of the AC adapter and USB supply.
The IC is powered from either the AC adapter, USB or the
battery, in that order of preference. The V
INT
voltage
powers up, followed by the Core, Main and Hot Swap
outputs.
At initial power up, the RESET pin is held low. When the
Core output comes into regulation, the RESET timer is
started. After a 262ms timeout, the RESET pin is released.
This allows the microprocessor to turn on. The micropro-
cessor in turn pulls PWRON high. After the PWRON pin is
pulled high, the PWRKEY pin can be released. There is a
400k
pull-up resistor on the PWRKEY pin.
The PWRKEY pin serves the dual purpose of turning on
and off the IC. During regular operation, if PWRKEY is
pressed low, the microprocessor detects this by monitor-
ing the status of PBSTAT pin. The PBSTAT pin goes low
whenever the PWRKEY pin is pulled low. The micropro-
cessor then goes into shutdown mode and pulls the
PWRON pin low. This results in powering off the LTC3456.
Figure 8 shows the device power-on/power-off sequence.
Figure 7. Maximum Output Current vs Battery Voltage
V
BATT
(V)
1.8
V
C
400
500
600
2.4
2.8
3456 G18
300
200
2
2.2
2.6
3
3.2
100
0
L = 10
μ
H
(BATTERY POWERED)
V
CORE
= 1.5V
V
CORE
= 1.8V
V
MAX
OUTPUT
A special internal PowerPath controller monitors the V
BATT
,
V
INT
, V
EXT
and USB voltages and passes the highest
available supply voltage to the V
MAX
pin. This pin is used
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| LTC3456EUF#TRPBF | 功能描述:IC CONV DC/DC USB BATT 24-QFN RoHS:否 类别:集成电路 (IC) >> PMIC - 电源管理 - 专用 系列:- 标准包装:1 系列:- 应用:手持/移动设备 电流 - 电源:- 电源电压:3 V ~ 5.5 V 工作温度:-40°C ~ 85°C 安装类型:表面贴装 封装/外壳:14-WFDFN 裸露焊盘 供应商设备封装:14-LLP-EP（4x4） 包装:Digi-Reel® 配用:LP3905SD-30EV-ND - BOARD EVALUATION LP3905SD-30 其它名称:LP3905SD-30DKR |
| LTC3458 | 制造商:LINER 制造商全称:Linear Technology 功能描述:1.7A, 1.5MHz Synchronous Step-Up DC/DC Converter with Output Disconnect |
| LTC3458EDE | 功能描述:IC REG BOOST SYNC ADJ 1.4A 12DFN 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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