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参数资料
| 型号： | MAX1778EUG+ |
| 厂商： | Maxim Integrated Products |
| 文件页数： | 24/39页 |
| 文件大小： | 0K |
| 描述： | IC DCDC CONV MULTI OUT 24TSSOP |
| 产品培训模块： | Lead (SnPb) Finish for COTS Obsolescence Mitigation Program |
| 标准包装： | 62 |
| 应用： | 转换器，TFT，LCD |
| 输入电压： | 2.7 V ~ 5.5 V |
| 输出数： | 5 |
| 输出电压： | 2.7 V ~ 13 V |
| 工作温度： | 0°C ~ 85°C |
| 安装类型： | 表面贴装 |
| 封装/外壳： | 24-TSSOP（0.173"，4.40mm 宽） |
| 供应商设备封装： | 24-TSSOP |
| 包装： | 管件 |
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MAX1778/MAX1880–MAX1885
Quad-Output TFT LCD DC/DC
Converters with Buffer
(I LX(MAX) ). If the output does not reach regulation within
1ms, soft-start enters phase II, and the current limit is
increased by another 25%. This process is repeated for
phase III. The maximum 1.5A (typ) current limit is
reached within 3072 clock cycles or when the output
reaches regulation, whichever occurs first (see the
startup waveforms in the Typical Operating
Characteristics).
For the charge pumps (MAX1778/MAX1880–MAX1882
only), soft-start is achieved by controlling the rate of
rise of the output voltage. Both charge-pump output
voltages are controlled to be in regulation within 4096
clock cycles, irregardless of output capacitance and
load, limited only by the charge pump’s output imped-
ance. Although the MAX1883–MAX1885 controllers do
not include the charge pumps, the soft-start logic still
contains the 4096 clock cycle startup periods for both
charge pumps.
Fault Trip Level (FLTSET)
The MAX1778/MAX1880–MAX1885 feature dual-mode
operation to allow operation with either a preset fault
trip level or an adjustable trip level for the step-up con-
verter and positive charge-pump outputs. Connect
FLTSET to GND to select the preset 0.9 V REF fault
threshold. The fault trip level can also be adjusted by
connecting a voltage-divider from REF to FLTSET
(Figure 8). For greatest accuracy, the total load on the
reference (including current through the negative
charge-pump feedback resistors) should not exceed
50μA so that V REF is guaranteed to be in regulation
(see the Electrical Characteristics). Therefore, select
R10 in the 100k ? to 1M ? range, and calculate R9 with
the following equation:
R9 = R10 [(V REF /V FLTSET ) - 1]
where V REF = 1.25V, and V FLTSET can range from 0.67
x V REF to 0.85 x V REF . FLTSET’s input bias current has
a maximum value of 50nA. For 1% error, the current
through R10 should be at least 100 times the FLTSET
input bias current (I FLTSET ).
Fault Condition
Once RDY is low, if the output of the main regulator or
either low-power charge pump falls below its fault
detection threshold, or if the input drops below its
undervoltage threshold, then RDY goes high impedance
set by FLTSET (see the Fault Trip Level ( FLTSET ) sec-
tion). For the negative charge pump, the fault threshold
measured at the charge-pump’s feedback input (FBN) is
140mV (typ).
Power Ready ( R D Y )
RDY is an open-drain output. When the power-up
sequence for the main step-up converter and low-
power charge pumps has properly completed, the 14V
MOSFET turns on and pulls RDY low with a 125 ? (typ)
on-resistance. If a fault is detected on any of these
three outputs, the internal open-drain MOSFET appears
as a high impedance. Connect a 100k ? pullup resistor
between RDY and IN for a logic-level output.
Voltage Reference (REF)
The voltage at REF is nominally 1.25V. The reference can
source up to 50μA with good load regulation (see the
Typical Operating Characteristics). Connect a 0.22μF
ceramic bypass capacitor between REF and GND.
Thermal-Overload Protection
Thermal-overload protection limits total power dissipa-
tion in the MAX1778/MAX1880–MAX1885. When the
junction temperature exceeds T J = +160°C, a thermal
sensor activates the fault protection, which shuts down
the controller, allowing the IC to cool. Once the device
cools down by 15°C, toggle shutdown (below 0.8V) or
cycle the input voltage (below 0.2V) to clear the fault
latch and reactivate the controller. Thermal-overload
protection protects the controller in the event of fault
conditions. For continuous operation, do not exceed
the absolute maximum junction-temperature rating of
T J = +150°C.
Operating Region and Power Dissipation
The MAX1778/MAX1880–MAX1885s’ maximum power
dissipation depends on the thermal resistance of the IC
package and circuit board, the temperature difference
between the die junction and ambient air, and the rate
of any airflow. The power dissipated in the device
depends on the operating conditions of each regulator
and the buffer.
The step-up controller dissipates power across the
internal n-channel MOSFET as the controller ramps up
the inductor current. In continuous conduction, the
power dissipated internally can be approximated by:
P STEP ? UP ≈ ? ? MAIN MAIN ?
? ? V IN ?
1 ? V IN D ? ?
12 ? ? f OSC L ? ? ?
and all outputs shut down; however, the reference
remains active. After removing the fault condition, toggle
shutdown (below 0.8V) or cycle the input voltage (below
0.2V) to clear the fault latch and reactivate the device.
The reference fault threshold is 1.05V. For the step-up
converter and positive charge-pump, the fault trip level is
24
? ? I V ?
?
× R DS ( ON ) D
2 2 ?
+
?
Maxim Integrated
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相关代理商/技术参数 |
参数描述 |
|---|---|
| MAX1778EUG+ | 功能描述:直流/直流开关转换器 Quad-Output TFT LCD w/Buffer RoHS:否 制造商:STMicroelectronics 最大输入电压:4.5 V 开关频率:1.5 MHz 输出电压:4.6 V 输出电流:250 mA 输出端数量:2 最大工作温度:+ 85 C 安装风格:SMD/SMT |
| MAX1778EUG+T | 功能描述:直流/直流开关转换器 Quad-Output TFT LCD w/Buffer RoHS:否 制造商:STMicroelectronics 最大输入电压:4.5 V 开关频率:1.5 MHz 输出电压:4.6 V 输出电流:250 mA 输出端数量:2 最大工作温度:+ 85 C 安装风格:SMD/SMT |
| MAX1778EUG-T | 功能描述:直流/直流开关转换器 RoHS:否 制造商:STMicroelectronics 最大输入电压:4.5 V 开关频率:1.5 MHz 输出电压:4.6 V 输出电流:250 mA 输出端数量:2 最大工作温度:+ 85 C 安装风格:SMD/SMT |
| MAX1778EVKIT | 功能描述:电源管理IC开发工具 MAX1778/80/81/82 Eval Kit RoHS:否 制造商:Maxim Integrated 产品:Evaluation Kits 类型:Battery Management 工具用于评估:MAX17710GB 输入电压: 输出电压:1.8 V |
| MAX1779EUE | 功能描述:直流/直流开关转换器 RoHS:否 制造商:STMicroelectronics 最大输入电压:4.5 V 开关频率:1.5 MHz 输出电压:4.6 V 输出电流:250 mA 输出端数量:2 最大工作温度:+ 85 C 安装风格:SMD/SMT |
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