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参数资料
| 型号： | MAX6479BL24BD3-T |
| 厂商： | MAXIM INTEGRATED PRODUCTS INC |
| 元件分类： | 固定／可调正电压单路输出LDO稳压器 |
| 英文描述： | 300mA LDO Linear Regulators with Internal Microprocessor Reset Circuit |
| 中文描述： | FIXED/ADJUSTABLE POSITIVE LDO REGULATOR, PBGA9 |
| 封装： | UCSP-9 |
| 文件页数： | 2/20页 |
| 文件大小： | 896K |
| 代理商： | MAX6479BL24BD3-T |
MAX6469–MAX6484
300mA LDO Linear Regulators with Internal
Microprocessor Reset Circuit
10
______________________________________________________________________________________
remotely sense the output voltage of the device. Using
FB with an external NPN transistor, the current drive
capability can be increased according to the following
equation (Figure 2):
IOUT(TOTAL) = IOUT (
β+1)
The external NPN pass transistor must meet specifica-
tions for current gain, power dissipation, and collector
current. The beta influences the maximum output cur-
rent the circuit can deliver. The largest guaranteed out-
put current is given by ILOAD (max) = 300mA
× beta
(min). The transistor’s rated power dissipation must
exceed the actual power dissipated in the transistor.
The power dissipated (PD) equals the maximum load
current (ILOAD (max)) times the maximum input-to-out-
put voltage differential: PD = ILOAD (max)
× (VIN (max) -
VOUT). The rated transistor collector current must
exceed the maximum load current.
Reverse Leakage Protection
Reverse OUT to IN Current
An internal circuit monitors the MAX6469–MAX6484
input and output voltages. When the output voltage is
greater than the input voltage, the internal IN-to-OUT
pass transistor and parasitic diode turn off. An external
voltage applied to OUT does not reverse charge a bat-
tery or power source applied to IN (the leakage path
from OUT to IN is 0.01A typ). When the output voltage
exceeds the input voltage, OUT powers the device and
shutdown must be logic high (greater than 0.7 VOUT).
RESET asserts until IN exceeds OUT and OUT is above
the specified VTHOUT threshold (based on the selected
or adjusted regulator OUT nominal voltage).
Reverse OUT to Ground Current
The MAX6469–MAX6484 maintain a low OUT-to-GND
reverse-current flow when the IN power source is
removed. When IN floats (input battery removed) and
SHDN is pulled up to VOUT (by an external diode), the
OUT-to-GND current through the LDO is 40A (typ). The
regulator output can be held up with an external super
capacitor or backup battery at OUT until the IN battery is
replaced. The RESET output is asserted while the IN bat-
tery is removed to place the system in a low-power
mode. Volatile memory content is maintained until the
super capacitor or battery voltage drops below RAM
standby specifications. RESET deasserts when the IN
battery has been replaced and OUT exceeds the
desired reset threshold. For nonrechargeable backup
battery applications, place a reverse diode between
OUT and the backup battery (to prevent battery charg-
ing). The external diode does not affect the regulator’s
dropout voltage because it is not between the LDO out-
put and the processor/memory Vcc supply. The diode
can be replaced with a current-limiting resistor for
rechargeable backup battery applications.
Current Limit
The MAX6469–MAX6484 include an internal current-
limit circuit that monitors and controls the pass transis-
tor’s gate voltage, limiting the output current to 450mA
(min). The output can be shorted to ground indefinitely
without damaging the part.
Thermal Shutdown
When the junction temperature (TJ) exceeds +180°C
(typ), the thermal sensor signals the shutdown logic,
turning off the pass transistor and allowing the IC to
Figure 3. Battery Backup
MAX6469–
MAX6484
P
MEMORY
OUT
IN
SHDN
3.0V
LITHIUM
REMOVABLE
LITHIUM ION OR
3-CELL
ALKALINE
REMOVABLE
LITHIUM ION OR
3-CELL
ALKALINE
MAX6469–
MAX6484
P
MEMORY
OUT
IN
SHDN
SUPERCAP
3.3
F
3.3
F
Figure 2. High-Current, External Transistor Application
MAX6475/MAX6476
MAX6483/MAX6484
RPULLUP
0.1
F
3.3
F
330
P
5.0V
OUT
FB
RESET
GND
IN
VCC = 3.3V
1A TOTAL CURRENT
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相关代理商/技术参数 |
参数描述 |
|---|---|
| MAX6479BL24BD4-T | 功能描述:低压差稳压器 - LDO RoHS:否 制造商:Texas Instruments 最大输入电压:36 V 输出电压:1.4 V to 20.5 V 回动电压（最大值）:307 mV 输出电流:1 A 负载调节:0.3 % 输出端数量: 输出类型:Fixed 最大工作温度:+ 125 C 安装风格:SMD/SMT 封装 / 箱体:VQFN-20 |
| MAX6479BL25AD1-T | 功能描述:低压差稳压器 - LDO RoHS:否 制造商:Texas Instruments 最大输入电压:36 V 输出电压:1.4 V to 20.5 V 回动电压（最大值）:307 mV 输出电流:1 A 负载调节:0.3 % 输出端数量: 输出类型:Fixed 最大工作温度:+ 125 C 安装风格:SMD/SMT 封装 / 箱体:VQFN-20 |
| MAX6479BL25AD2-T | 功能描述:低压差稳压器 - LDO RoHS:否 制造商:Texas Instruments 最大输入电压:36 V 输出电压:1.4 V to 20.5 V 回动电压（最大值）:307 mV 输出电流:1 A 负载调节:0.3 % 输出端数量: 输出类型:Fixed 最大工作温度:+ 125 C 安装风格:SMD/SMT 封装 / 箱体:VQFN-20 |
| MAX6479BL25AD3-T | 功能描述:低压差稳压器 - LDO RoHS:否 制造商:Texas Instruments 最大输入电压:36 V 输出电压:1.4 V to 20.5 V 回动电压（最大值）:307 mV 输出电流:1 A 负载调节:0.3 % 输出端数量: 输出类型:Fixed 最大工作温度:+ 125 C 安装风格:SMD/SMT 封装 / 箱体:VQFN-20 |
| MAX6479BL25AD4-T | 功能描述:低压差稳压器 - LDO RoHS:否 制造商:Texas Instruments 最大输入电压:36 V 输出电压:1.4 V to 20.5 V 回动电压（最大值）:307 mV 输出电流:1 A 负载调节:0.3 % 输出端数量: 输出类型:Fixed 最大工作温度:+ 125 C 安装风格:SMD/SMT 封装 / 箱体:VQFN-20 |
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