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| 型号： | MAX5053BEUA+ |
| 厂商： | Maxim Integrated Products |
| 文件页数： | 8/13页 |
| 文件大小： | 0K |
| 描述： | IC REG CTRLR BST ISO PWM 8-UMAX |
| 产品培训模块： | Lead (SnPb) Finish for COTS Obsolescence Mitigation Program |
| 标准包装： | 50 |
| PWM 型： | 电流模式 |
| 输出数： | 1 |
| 频率 - 最大： | 290kHz |
| 占空比： | 76% |
| 电源电压： | 10.8 V ~ 24 V |
| 降压： | 无 |
| 升压： | 是 |
| 回扫： | 无 |
| 反相： | 无 |
| 倍增器： | 无 |
| 除法器： | 无 |
| Cuk： | 无 |
| 隔离： | 是 |
| 工作温度： | -40°C ~ 85°C |
| 封装/外壳： | 8-TSSOP，8-MSOP（0.118"，3.00mm 宽） |
| 包装： | 管件 |
Current-Mode PWM Controllers with an Error
Amplifier for Isolated/Nonisolated Power Supplies
where I IN is the MAX5052’s internal supply current after
V CC
2V/div
MAX5052
V IN PIN
5V/div
startup (1.4mA), Q gtot is the total gate charge for Q1,
f SW is the MAX5052’s switching frequency (262kHz),
V hyst is the bootstrap UVLO hysteresis (12V) and t ss is
the internal soft-start time (60ms).
For example:
I g = (8nC) (262kHz) ? 2.1mA
0V
C1 =
( 1.4m A + 2.1m A ) ( 6 0m s )
( 1 2V )
= 1 7.5 μ F
I C 1 = SUVR
100ms/div
Figure 2. V IN and V CC During Startup when Using the
MAX5052 in Bootstrapped Mode (Figure 1)
If V IN drops below 9.9V before startup is complete, the
device goes back to low-current UVLO. In this case,
choose 15μF standard value.
Assuming C1 > C2, calculate the value of R1 as follows:
V × C1
( 500 ms )
increase the value of C1 in order to store enough energy
to allow for the voltage at tertiary winding to build up.
R 1 =
V IN ( MIN ) ? V SUVR
I C 1 + I START
Startup Time Considerations For Power
Supplies Using the MAX5052
The V IN bypass capacitor, C1, supplies current imme-
diately after wake up (see Figure 1). The size of C1 and
the connection configuration of the tertiary winding
determine the number of cycles available for startup.
where V IN(MIN) is the minimum input supply voltage for
the application (36V for telecom), V SUVR is the boot-
strap UVLO wake-up level (23.6V max.), I START is the
V IN supply current at startup (90μA, max).
For example:
Large values of C1 increase the startup time but also
supply gate charge for more cycles during initial start-
up. If the value of C1 is too small, V IN drops below 9.9V
because NDRV does not have enough time to switch
I C1 =
( 24V ) ( 15 μ F ) = 0 . 72 mA
( 500 ms )
( ) + ( )
and build up sufficient voltage across the tertiary output
which powers the device. The device goes back into
UVLO and does not start. Use a low-leakage capacitor
for C1 and C2.
R 1 =
( 36 V ) ? ( 12 V )
0 . 72 mA 90 μ A
= 29 . 6 k ?
As a rule of thumb, offline power supplies keep typical
startup times to less than 500ms even in low-line condi-
tions (85VAC input for universal offline or 36VDC for
telecom applications). Size the startup resistor, R1, to
supply both the maximum startup bias of the device
(90μA) and the charging current for C1 and C2. The
bypass capacitor, C2, must charge to 9.5V and C1 to
24V, all within the desired time period of 500ms.
Because of the internal 60ms soft-start time of the
MAX5052, C1 must store enough charge to deliver cur-
rent to the device for at least this much time. To calcu-
late the approximate amount of capacitance required,
use the following formula:
I g = Q gtot × f SW
choose 32k ? standard value.
Choose a higher value for R1 than the one calculated
above if longer startup time can be tolerated in order to
minimize power loss on this resistor.
The above startup method is applicable to a circuit simi-
lar to the one shown in Figure 1. In this circuit, the tertiary
winding has the same phase as the output windings.
Thus, the voltage on the tertiary winding at any given
time is proportional to the output voltage and goes
through the same soft-start period as the output voltage.
The minimum discharge voltage of C1 from 22V to 10V
must be greater than the soft-start time of 60ms.
Another method for bootstrapping the power supply is to
have a separate bias winding than the one used for reg-
C 1 =
( I IN + I g ) ( t SS )
V hyst
ulating the output voltage and to connect the bias wind-
ing so that it is in phase with the MOSFET ON time (see
Figure 3). The amount of capacitance required is much
8
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相关代理商/技术参数 |
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|---|---|
| MAX5053BEUA+ | 功能描述:电流型 PWM 控制器 w/Error Amplifier 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 |
| MAX5053BEUA+T | 功能描述:电流型 PWM 控制器 w/Error Amplifier 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 |
| MAX5053BEUA-T | 功能描述:电流型 PWM 控制器 w/Error Amplifier 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 |
| MAX5054 | 制造商:MAXIM 制造商全称:Maxim Integrated Products 功能描述:4A, 20ns, Dual MOSFET Drivers |
| MAX5054_10 | 制造商:MAXIM 制造商全称:Maxim Integrated Products 功能描述:4A, 20ns, Dual MOSFET Drivers |
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