参数资料
型号: MIC68220YML TR
厂商: Micrel Inc
文件页数: 13/17页
文件大小: 0K
描述: IC REG LDO ADJ 1A 20MLF
标准包装: 1
稳压器拓扑结构: 正,可调式
输出电压: 0.5 V ~ 5.5 V
输入电压: 1.65 V ~ 5.5 V
电压 - 压降(标准): 0.3V @ 2A
稳压器数量: 2
电流 - 输出: 1A
电流 - 限制(最小): 2A
工作温度: -40°C ~ 125°C
安装类型: 表面贴装
封装/外壳: 20-VFDFN,20-MLF?
供应商设备封装: 20-MLF?(4x5)
包装: 标准包装
产品目录页面: 1109 (CN2011-ZH PDF)
其它名称: 576-1612-6
Micrel
Adjustable Regulator Design
Adjustable Regulator with Resistors
The adjustable MIC68220 output voltage can be
programmed from 0.5V to 5.5V using a resistor divider
from output to the SNS pin. Resistors can be quite
large, up to 1M ? because of the very high input
impedance and low bias current of the sense
amplifier. Typical sense input currents are less than
30nA which causes less than 0.3% error with R1 and
R2 less than or equal to 100K ? . For large value
resistors (>50K) R1 should be bypassed by a small
capacitor (C FF = 0.1μF bypass capacitor) to avoid
instability due to phase lag at the ADJ/SNS input.
The output resistor divider values are calculated by:
MIC68220
Scale Factor is:
1.1 seconds/microfarad,
1.1 milliseconds/nanofarad, or
1.1 microseconds/picofarad.
T DLYOFF is the time from lowering of EN to the start of
ramp down on the off cycle. T POR is the time from
raising of EN to the release (low to high edge) of the
POR. This behavior means that a μP or other
complex logic system guarantees that power has
been good for a known time before the POR is
released. They are further guaranteed that once POR
is pulled low, they have a known time to ‘tidy up’
memory or other registers for a well controlled
shutdown. In Master/Slave configurations the timers
can be used to assure that the Master is always
accurately regulating when the Slave is on.
Ramp Control
The ramp control (RC) has a bidirectional current
source and a sense amplifier, which together are used
to control the voltage at the output. When RC is below
the target voltage (nominal output voltage for fixed
voltage parts, 0.5V for adjustable parts) the RC pin
V OUT = 0.5V ?
+ 1 ?
? R1
? R2
?
?
controls the output voltage. When RC is at or above
the target voltage, the output is controlled by the
internal regulator.
Power on Reset (POR) and Delay (DLY)
The power-on reset output (POR) is an open-drain
N-Channel device requiring a pull-up resistor to either
the input voltage or output voltage for proper voltage
levels. POR is driven by the internal timer so that the
release of POR at turn-on can be delayed for as much
as 1 second. POR is always pulled low when enable
(EN) is pulled low or the output goes out of regulation
by more than 10% due to loading conditions.
The internal timer is controlled by the DLY pin which
has a bidirectional current source and two limiting
comparators. A capacitor connected from DLY-to-
GND sets the delay time for two functions. On start
up, DLY sets the time from power good to the release
of the POR. At shut down, the delay sets the time
from disable (EN pin driven low) to actual ramp down
of the output voltage. The current source is +/-1μA,
which charges the capacitor from ~150mV (nominal
disabled DLY voltage) to ~1.25V. At turn on, the DLY
cap begins to charge when the output voltage reaches
90% of the target value. When the capacitor reaches
1.25V, the output of the POR is released to go high.
At turn off, the DLY cap begins to discharge when the
EN is driven low. When the cap reaches ~150mV the
output is ramped down. Both delays are nominally the
same, and are calculated by the same formula:
Tracking Applications: Driving RC from a Voltage
Source
Fixed Parts: If RC is driven from another (Master)
regulator the two outputs will track each other until the
Master exceeds the target voltage of the Slave
regulator. Typically the output of the MIC68220 will
track above the RC input by 30mV to 70mV. This
offset is designed to allow Master/Slave tracking of
same-voltage regulators. Without the offset, same-
voltage Master/Slave configurations could suffer poor
regulation.
Adjustable Parts: The RC pin on adjustable versions
operates from 0V to 0.5V. To implement tracking on
an adjustable version, an external resistor divider
must be used. This divider is the nearly same ratio as
the voltage setting divider used to drive the Sense/Adj
pin. It is recommended that the ratio be adjusted to
track ~50mV (2% to 3%) above the target voltage if
the Master and Slave are operating at the same target
voltage.
T DLY = ( 1.1 ) ? ? DLY
? ?
? C
? 1 μ A
?
?
September 2010
13
M9999-092310-C
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MIC68400-1.0YML TR 功能描述:IC REG LDO 1V 3A 16-MLF RoHS:是 类别:集成电路 (IC) >> PMIC - 稳压器 - 线性 系列:- 标准包装:1 系列:- 稳压器拓扑结构:正,固定式 输出电压:3V 输入电压:2.3 V ~ 5.5 V 电压 - 压降(标准):0.035V @ 150mA 稳压器数量:2 电流 - 输出:150mA 电流 - 限制(最小):300mA 工作温度:-40°C ~ 125°C 安装类型:表面贴装 封装/外壳:6-UFDFN 裸露焊盘,6-TMLF? 供应商设备封装:6-TMLF?(1.6x1.6) 包装:Digi-Reel® 产品目录页面:1104 (CN2011-ZH PDF) 其它名称:576-3018-6
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