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| 型号： | MAX8553EEE+T |
| 厂商： | Maxim Integrated Products |
| 文件页数： | 16/24页 |
| 文件大小： | 0K |
| 描述： | IC CNTRLR BUCK PWM 16-QSOP |
| 产品培训模块： | Lead (SnPb) Finish for COTS Obsolescence Mitigation Program |
| 标准包装： | 2,500 |
| 系列： | Quick-PWM™ |
| 应用： | 控制器，DDR，DDR2 |
| 输入电压： | 4.5 V ~ 28 V |
| 输出数： | 1 |
| 输出电压： | 可调 |
| 工作温度： | -40°C ~ 85°C |
| 安装类型： | 表面贴装 |
| 封装/外壳： | 16-SSOP（0.154"，3.90mm 宽） |
| 供应商设备封装： | 16-QSOP |
| 包装： | 带卷 (TR) |
4.5V to 28V Input, Synchronous PWM Buck Controllers
for DDR Termination and Point-of-Load Applications
Table 1. Configuration of FSEL (MAX8553)
FSEL CONNECTED TO
Ground
REF
Floating
VL
N
1.07
1.33
2.00
3.00
t ON (μs)
0.91
1.15
1.70
2.55
FREQUENCY (kHz)
550
400
300
200
CONDITION
V OUT / V EN/HSD = 0.5
V OUT / V EN/HSD = 0.5
V OUT / V EN/HSD = 0.5
V OUT / V EN/HSD = 0.5
Table 2. Configuration of FSEL (MAX8554)
FSEL CONNECTED TO
Ground
REF
Floating
VL
N
1.07
1.33
2.00
3.00
t ON (μs)
0.37
0.49
0.71
1.02
FREQUENCY (kHz)
550
400
300
200
CONDITION
V HSD = 12V, V OUT = 2.5V
V HSD = 12V, V OUT = 2.5V
V HSD = 12V, V OUT = 2.5V
V HSD = 12V, V OUT = 2.5V
This algorithm results in a nearly constant switching fre-
quency despite the lack of a fixed-frequency clock
generator. The actual switching frequency, which is
given by the following equation, varies slightly due to
the voltage drop across the on-resistance of the
MOSFETs and the DC resistance of the output inductor:
VTTR Reference (MAX8553 Only)
The MAX8553’s VTTR output is capable of sourcing or
sinking up to 25mA of current. The VTTR output voltage
is one-half of the voltage applied to REFIN. Bypass
VTTR with at least a 1μF ceramic capacitor.
Voltage Reference
f S = ?
D
t ON
where D is the duty cycle:
1
K × N
The voltage at REF is nominally 2.00V. Connect a 0.22μF
ceramic bypass capacitor between REF and GND.
EN and HSD (MAX8554 Only)
EN is a logic input used to enable or shut down the
V HSD + I O ( R DSONL DSONH )
D =
V OUT + I O ( R DSONL + R DC )
- R
MAX8554. Drive EN high or connect to V+ to enable the
output. Drive EN low to place the MAX8554 in low-
power shutdown mode, reducing input current to less
than 5μA (typ).
where I O is the output current, R DSONL is the on-resis-
tance of the low-side MOSFET, R DSONH is the on-resis-
tance of the high-side MOSFET, and R DC is the DC
resistance of the output inductor. The ideal switching fre-
quency for V REFIN = 2.5V is about 550kHz. Switching fre-
quency increases for positive (sourcing) load current
and decreases for negative (sinking) load current, due to
the changing voltage drop across the low-side MOSFET,
which changes the inductor-current discharge ramp
rate. The on-times guaranteed in the Electrical
Characteristics are also influenced by switching delays
caused by the loading effect of the external power
MOSFETs.
The switching frequency can also be adjusted to a
value other than the preset frequencies by adding a
resistor voltage-divider at HSD. See the Adjusting the
Switching Frequency section.
HSD senses the input voltage at the drain of the high-side
MOSFET, which is used to set the high-side MOSFET on-
time. For normal operation, connect HSD to the drain of
the high-side MOSFET.
EN/HSD Function (MAX8553 Only)
In order to reduce pin count and package size, the
MAX8553 features a dual-function input pin, EN/HSD.
When EN/HSD is pulled to ground, the internal circuitry
powers off, reducing current consumption to less than
5μA (typ). To enable normal operation, connect
EN/HSD to the drain of the high-side MOSFET through
a 5.1k ? resistor ( Figure 2). In this configuration, EN/HSD
becomes an input that monitors the high-side MOSFET
drain voltage (converter input voltage) and uses that
measurement to calculate the appropriate on-time for the
converter. If the enable function is not used, connect
EN/HSD directly to the high-side MOSFET drain.
16
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相关代理商/技术参数 |
参数描述 |
|---|---|
| MAX8554EEE | 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 |
| MAX8554EEE+ | 功能描述:电流型 PWM 控制器 4.5-28V Input Synch Buck 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 |
| MAX8554EEE+T | 功能描述:电流型 PWM 控制器 4.5-28V Input Synch Buck 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 |
| MAX8554EEE-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 |
| MAX8554EVKIT | 功能描述:电流型 PWM 控制器 Evaluation Kit for the MAX8553 MAX8554 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 |
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