- 您现在的位置：买卖IC网 > PDF目录5134 > MAX8742EAI+T (Maxim Integrated Products)IC CNTRLR PWR SUP 28-SSOP PDF资料下载
参数资料
| 型号： | MAX8742EAI+T |
| 厂商： | Maxim Integrated Products |
| 文件页数： | 18/34页 |
| 文件大小： | 0K |
| 描述： | IC CNTRLR PWR SUP 28-SSOP |
| 产品培训模块： | Lead (SnPb) Finish for COTS Obsolescence Mitigation Program |
| 标准包装： | 2,000 |
| 应用： | 控制器，笔记本电脑电源系统 |
| 输入电压： | 4.2 V ~ 30 V |
| 输出数： | 2 |
| 输出电压： | 3.3V，5V，2.5 V ~ 5.5 V |
| 工作温度： | 0°C ~ 85°C |
| 安装类型： | 表面贴装 |
| 封装/外壳： | 28-SSOP（0.209"，5.30mm 宽） |
| 供应商设备封装： | 28-SSOP |
| 包装： | 带卷 (TR) |
第1页第2页第3页第4页第5页第6页第7页第8页第9页第10页第11页第12页第13页第14页第15页第16页第17页当前第18页第19页第20页第21页第22页第23页第24页第25页第26页第27页第28页第29页第30页第31页第32页第33页第34页
500kHz Multi-Output Power-Supply Controllers
with High Impedance in Shutdown
DL_ is kept low whenever the corresponding SMPS is
disabled, and in shutdown. Since the outputs are not
actively discharged by the SMPS controller, the negative
output voltage caused by quickly discharging the output
through the inductor and low-side MOSFET is eliminated.
The output voltage discharges at a rate determined only
by the output capacitance and load current.
RESET Power-Good Voltage Monitor
The power-good monitor generates a system RESET
signal. At first power-up, RESET is held low until both
the 3.3V and 5V SMPS outputs are in regulation. At this
point, an internal timer begins counting oscillator puls-
es, and RESET continues to be held low until 32,000
cycles have elapsed. After this timeout period (64ms at
500kHz or 96ms at 333kHz), RESET is actively pulled
up to V L . If SEQ is connected to REF (for separate
ON3/ON5 controls), only the 3.3V SMPS is monitored—
the 5V SMPS is ignored.
Output Undervoltage Shutdown Protection
The output undervoltage-lockout circuit is similar to
foldback current limiting, but employs a timer rather
than a variable current limit. Each SMPS has an under-
voltage protection circuit that is activated 4096 clock
cycles after the SMPS is enabled. If either SMPS output
is under 70% of the nominal value, both SMPSs are
latched off with DH_ and DL_ driven low. They won’t
restart until SHDN or RUN/ON3 is toggled, or until V+
power is cycled below 1V.
Output Overvoltage Protection
Both SMPS outputs are monitored for overvoltage. If
either output is more than 7% above the nominal regu-
lation point, both SMPS outputs are latched off and the
low-side gate driver (DL_) of the faulted side is latched
Table 4. Operating Modes
high. The SMPS does not restart until SHDN is brought
low and V L falls below its 2V (typ) POR level.
To ensure overvoltage protection on initial power-up,
connect signal diodes from both output voltages to V L
(cathodes to V L ) to eliminate the V L power-up delay.
This circuitry protects the load from accidental overvolt-
age caused by a short circuit across the high-side
power MOSFETs. This scheme relies on the presence
of a fuse, in series with the battery, which is blown by
the resulting crowbar current.
Low-Noise Operation (PWM Mode)
PWM mode ( SKIP = high) minimizes RF and audio inter-
ference in noise-sensitive applications (such as hi-fi multi-
media-equipped systems), cellular phones, RF
communicating computers, and electromagnetic pen
entry systems. See the summary of operating modes in
Table 3. SKIP can be driven from an external logic signal.
Interference due to switching noise is reduced in PWM
mode by ensuring a constant switching frequency, thus
concentrating the emissions at a known frequency out-
side the system audio or IF bands. Choose an oscillator
frequency for which switching frequency harmonics do
not overlap a sensitive frequency band. If necessary,
synchronize the oscillator to a tight-tolerance external
clock generator. To extend the output-voltage regula-
tion range, constant operating frequency is not main-
tained under overload or dropout conditions (see the
Dropout Operation section).
PWM mode ( SKIP = high) forces two changes upon the
PWM controllers. First, it disables the minimum-current
comparator, ensuring fixed-frequency operation.
Second, it changes the detection threshold for reverse
current limit from 0 to -100mV, allowing the inductor
SHDN
Low
High
High
High
High
High
High
High
High
SEQ
X
REF
REF
REF
REF
GND
GND
V L
V L
RUN/ON3
X
Low
High
Low
High
Low
High
Low
High
TIME/ON5
X
Low
Low
High
High
Timing capacitor
Timing capacitor
Timing capacitor
Timing capacitor
MODE
Shutdown
Standby
Run
Run
Run
Standby
Run
Standby
Run
DESCRIPTION
All circuit blocks turned off.
Supply current = 4μA.
Both SMPSs off. Supply current = 30μA.
3.3V SMPS enabled/5V off.
5V SMPS enabled/3.3V off.
Both SMPSs enabled.
Both SMPSs off. Supply current = 30μA.
Both SMPSs enabled. 5V enabled before 3.3V.
Both SMPSs off. Supply current = 30μA.
Both SMPSs enabled. 3.3V enabled before 5V.
18
______________________________________________________________________________________
相关PDF资料 |
PDF描述 |
|---|---|
| MAX8741EAI+T | IC CNTRLR PWR SUP 28-SSOP |
| SH471M010ST | CAP ALUM 470UF 10V 20% RADIAL |
| RYM43DTAH | CONN EDGECARD 86POS R/A .156 SLD |
| RYM43DTAD | CONN EDGECARD 86POS R/A .156 SLD |
| RCC50DRXH | CONN EDGECARD 100PS DIP .100 SLD |
相关代理商/技术参数 |
参数描述 |
|---|---|
| MAX8743EEI | 功能描述:电流型 PWM 控制器 RoHS:否 制造商:Texas Instruments 开关频率:27 KHz 上升时间: 下降时间: 工作电源电压:6 V to 15 V 工作电源电流:1.5 mA 输出端数量:1 最大工作温度:+ 105 C 安装风格:SMD/SMT 封装 / 箱体:TSSOP-14 |
| MAX8743EEI+ | 功能描述:电流型 PWM 控制器 Dual Step-Down Controller RoHS:否 制造商:Texas Instruments 开关频率:27 KHz 上升时间: 下降时间: 工作电源电压:6 V to 15 V 工作电源电流:1.5 mA 输出端数量:1 最大工作温度:+ 105 C 安装风格:SMD/SMT 封装 / 箱体:TSSOP-14 |
| MAX8743EEI+T | 功能描述:电流型 PWM 控制器 Dual Step-Down Controller RoHS:否 制造商:Texas Instruments 开关频率:27 KHz 上升时间: 下降时间: 工作电源电压:6 V to 15 V 工作电源电流:1.5 mA 输出端数量:1 最大工作温度:+ 105 C 安装风格:SMD/SMT 封装 / 箱体:TSSOP-14 |
| MAX8743EEI-T | 功能描述:电流型 PWM 控制器 RoHS:否 制造商:Texas Instruments 开关频率:27 KHz 上升时间: 下降时间: 工作电源电压:6 V to 15 V 工作电源电流:1.5 mA 输出端数量:1 最大工作温度:+ 105 C 安装风格:SMD/SMT 封装 / 箱体:TSSOP-14 |
| MAX8743ETX | 功能描述:电流型 PWM 控制器 RoHS:否 制造商:Texas Instruments 开关频率:27 KHz 上升时间: 下降时间: 工作电源电压:6 V to 15 V 工作电源电流:1.5 mA 输出端数量:1 最大工作温度:+ 105 C 安装风格:SMD/SMT 封装 / 箱体:TSSOP-14 |
发布紧急采购，3分钟左右您将得到回复。