參數(shù)資料
型號(hào): MAX8884YEREKE+T
廠商: Maxim Integrated
文件頁(yè)數(shù): 11/17頁(yè)
文件大小: 579K
描述: IC REG TRPL BCK/LINEAR 16UCSP
產(chǎn)品培訓(xùn)模塊: Lead (SnPb) Finish for COTS
Obsolescence Mitigation Program
標(biāo)準(zhǔn)包裝: 2,500
拓?fù)洌?/td> 降壓(降壓)同步(1),線性(LDO)(2)
功能: 任何功能
輸出數(shù): 3
頻率 - 開關(guān): 2MHz
電壓/電流 - 輸出 1: 1.2 V/1.8 V,700mA
電壓/電流 - 輸出 2: 1.2 V/1.8 V,300mA
電壓/電流 - 輸出 3: 1.2 V/1.8 V,300mA
帶 LED 驅(qū)動(dòng)器: 無(wú)
帶監(jiān)控器: 無(wú)
帶序列發(fā)生器: 無(wú)
電源電壓: 2.7 V ~ 5.5 V
工作溫度: -40°C ~ 85°C
安裝類型: 表面貼裝
封裝/外殼: 16-WFBGA,CSPBGA
供應(yīng)商設(shè)備封裝: 16-UCSP(4x4)
包裝: 帶卷 (TR)
700mA DC-DC Step-Down Converters
with Dual 300mA LDO in 2mm x 2mm CSP
______________________________________________________________________________________ 11
Thermal Shutdown
Thermal shutdown limits total power dissipation in the
MAX8884Y/MAX8884Z. If the junction temperature
exceeds +160癈, thermal shutdown circuitry turns off
the MAX8884Y/MAX8884Z, allowing the ICs to cool.
The ICs turn on and begin soft-start after the junction
temperature cools by 20癈. This results in a pulsed out-
put during continuous thermal-overload conditions.
Applications Information
Output Voltages
The MAX8884Y/MAX8884Z DC-DC step-down convert-
er sets the BUCK and LDO1 output voltage based on
the state of SEL. See Table 1.
Contact the factory for other output voltage options.
LDO Dropout Voltage
The regulators minimum input/output differential (or
dropout voltage) determines the lowest usable supply
voltage. In battery-powered systems, this determines the
useful end-of-life battery voltage. Because the
MAX8884Y/MAX8884Z LDOs use a p-channel MOSFET
pass transistor, their dropout voltages are a function of
drain-to-source on-resistance (R
DS(ON)
) multiplied by the
load current (see the Typical Operating Characteristics).
Inductor Selection
The MAX8884Y operates with a switching frequency of
2MHz and utilizes a 2.2礖 inductor. The MAX8884Z
operates with a switching frequency of 4MHz and uti-
lizes a 1礖 inductor. The higher switching frequency of
the MAX8884Z allows the use of physically smaller
inductors at the cost of lower efficiency. The lower
switching frequency of the MAX8884Y results in greater
efficiency at the cost of a physically larger inductor.
See the Typical Operating Characteristicsfor efficiency
graphs for both the MAX8884Y and the MAX8884Z.
The inductors DC current rating only needs to match the
maximum load of the application because the
MAX8884Y/MAX8884Z feature zero current overshoot
during startup and load transients. For optimum transient
response and high efficiency, choose an inductor with
DC series resistance in the 50m&to 150m&range. See
Table 2 for suggested inductors and manufacturers.
Output Capacitor Selection
For the DC-DC step-down converter, the output capacitor
C
BUCK
is required to keep the output voltage ripple small
and ensure regulation loop stability. C
BUCK
must have low
impedance at the switching frequency. Ceramic capaci-
tors with X5R or X7R dielectric are highly recommended
due to their small size, low ESR, and small temperature
coefficients. Due to the unique feedback network, the out-
put capacitance can be very low. A 2.2礔 ceramic capaci-
tor is recommended for most applications. For optimum
load-transient performance and very low output ripple, the
output capacitor value can be increased.
For LDO1 and LDO2, the minimum output capacitance
required is dependent on the load currents. For loads
lighter than 10mA, it is sufficient to use a 0.1礔 ceramic
capacitor for stable operation over the full temperature
range. For loads up to 200mA, an output capacitor of
1礔 is sufficient for stable operation over the entire tem-
perature range. Operating the LDO at maximum rated
current the LDO1 and LDO2 requires a 2.2礔 ceramic
capacitor. Using larger output capacitors reduces out-
put noise and improves load-transient response, stabili-
ty, and power-supply rejection.
Note that some ceramic dielectrics exhibit large capaci-
tance and ESR variation with temperature. With dielectrics
such as Z5U and Y5V, it is necessary to use 4.7礔 or more
to ensure stability at temperatures below -10癈. With X7R
or X5R dielectrics, 2.2礔 is sufficient at all operating tem-
peratures. These regulators are optimized for ceramic
capacitors. Tantalum capacitors are not recommended.
Input Capacitor Selection
The input capacitor (C
IN1
) of the DC-DC step-down
converter reduces the current peaks drawn from the
battery or input power source and reduces switching
noise in the MAX8884Y/MAX8884Z. The impedance of
C
IN1
at the switching frequency should be kept very
low. Ceramic capacitors with X5R or X7R dielectric are
highly recommended due to their small size, low ESR,
and small temperature coefficients. A 2.2礔 ceramic
capacitor is recommended for most applications. For
optimum noise immunity and low input ripple, the input
capacitor value can be increased.
For the LDOs, use an input capacitance equal to the
value of the sum of the output capacitance of LDO1 and
LDO2. Larger input capacitor values and lower ESR pro-
vide better noise rejection and line transient response.
Note that some ceramic dielectrics exhibit large capaci-
tance and ESR variation with temperature. With dielectrics
such as Z5U and Y5V, it may be necessary to use two
times the sum of the output capacitor value of LDO1 and
LDO2 (or larger) to ensure stability at temperatures below
-10癈. With X7R or X5R dielectrics, a capacitance equal
to the sum is sufficient at all operating temperatures.
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