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参数资料
| 型号： | MAX687CSA-T |
| 厂商： | MAXIM INTEGRATED PRODUCTS INC |
| 元件分类： | 固定正电压单路输出LDO稳压器 |
| 英文描述： | High-Accuracy, Low-Dropout Linear Regulators |
| 中文描述： | 3.3 V FIXED POSITIVE LDO REGULATOR, PDSO8 |
| 封装： | 0.150 INCH, SO-8 |
| 文件页数： | 9/12页 |
| 文件大小： | 103K |
| 代理商： | MAX687CSA-T |
2
MAX687/MAX688/MAX689
High-Accuracy, Low-Dropout
Linear Regulators
6
_______________________________________________________________________________________
______________________________________________________________Pin Description
NAME
FUNCTION
1
IN
Positive input voltage, 2.7V to 11.0V
2
ON
(MAX687)
ON activates the regulator when pulsed high. In order for the regulator to remain on, ON must remain high
until VOUT exceeds the internal shutdown threshold voltage. The MAX687 is shut down when VOUT < 2.96V,
and remains latched off until ON is pulsed high. When powered up, the MAX687 does not start up until ON
is pulsed high. Connect to VIN if not used.
PIN
SHDN
(MAX688/
MAX689)
SHDN is a three-level input that controls the mode of operation. The device is on when V SHDN > 1.25V.
The output is disabled and the supply current is reduced (IIN < 25A, standby mode) when V SHDN < 1.2V,
and is fully off (IIN < 1A, shutdown mode) when V SHDN < 0.2V. Connect SHDN to IN if the shutdown func-
tion is not used. PFO is low when SHDN is low (below 0.2V).
3
PFO
Power-Fail Output. PFO trips when VOUT is 170mV below nominal VOUT at IBASE = 1mA. PFO sources and
sinks current in the MAX687, but is an open drain in the MAX688/MAX689. When shut down, PFO is always
low and sinks current. Leave PFO open if not used.
7
BASE
Base drive for the external PNP transistor. Current limiting is controlled using a resistor (RB) connected
between BASE and BLIM. For maximum output current, connect BASE to BLIM.
6
BLIM
Base current limit. A resistor (RB) connected between BASE and BLIM sets the maximum base drive to the
PNP transistor: IBASE ≤ 0.1V / (RB + 5). This limits quiescent current rise during dropout and also pro-
vides current limiting without using a current-sense resistor in the collector of the external PNP, thus not
impacting dropout. Output current limiting accuracy depends on how well the external PNP beta (hFE) is
controlled. Connect to BASE if not used.
5
OUT
Regulator Output. MAX687/MAX688, 3.3V; MAX689, 3.0V.
4
GND
Ground
8
CC
Compensation Capacitor. Connect a non-polarized capacitor (10nF to 100nF) from CC to GND.
_______________Detailed Description
The MAX687/MAX688/MAX689 are precision low-
dropout linear regulators employing external PNP tran-
sistors to achieve a wide range of output currents at
voltages of 3.0V or 3.3V. The maximum base current
for the PNP can be limited using a resistor. Limiting the
base drive keeps high currents from being wasted
when the device is in dropout (e.g., at low input volt-
ages), and limits the regulator’s output current. The
dropout voltage is limited only by the PNP transistor’s
VCE(SAT). The Power-Fail Output (PFO) goes low when
the output voltage drops 170mV below the nominal
level.
The three devices differ in their output voltages, in their
shutdown-control functions, and in PFO’s output drive
(see Table 1).
The MAX687’s output voltage is internally monitored; a
falling VOUT is signaled by PFO going low. As the out-
put falls further, the MAX687 automatically enters a low-
power shutdown mode, where the base drive to the
external PNP is cut off. PFO trips at a minimum of
110mV below the nominal VOUT, and shutdown occurs
by 2.96V. PFO is guaranteed to trip before the device
Table 1. Device Functions
FUNCTION
MAX687
MAX688
MAX689
VOUT
3.3V
3.0V
Shutdown
Control
Automatic at low
VOUT. Latched.
Use ON to start.
External
SHDN
External
SHDN
PFO
Sources & Sinks
Open Drain
相关PDF资料 |
PDF描述 |
|---|---|
| MAX687CUA-T | High-Accuracy, Low-Dropout Linear Regulators |
| MAX687ESA-T | High-Accuracy, Low-Dropout Linear Regulators |
| MAX688CSA-T | High-Accuracy, Low-Dropout Linear Regulators |
| MAX688CUA-T | High-Accuracy, Low-Dropout Linear Regulators |
| MAX688ESA-T | High-Accuracy, Low-Dropout Linear Regulators |
相关代理商/技术参数 |
参数描述 |
|---|---|
| MAX687CUA | 功能描述:低压差稳压器 - LDO High-Accuracy 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 |
| MAX687CUA-T | 功能描述:低压差稳压器 - LDO High-Accuracy 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 |
| MAX687EPA | 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 |
| MAX687ESA | 功能描述:低压差稳压器 - LDO High-Accuracy 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 |
| MAX687ESA-T | 功能描述:低压差稳压器 - LDO High-Accuracy 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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