- 您现在的位置：买卖IC网 > PDF目录383343 > MAX1970EEE (MAXIM INTEGRATED PRODUCTS INC) Fixed-Point Digital Signal Processor 532-FCBGA PDF资料下载
参数资料
| 型号： | MAX1970EEE |
| 厂商： | MAXIM INTEGRATED PRODUCTS INC |
| 元件分类： | 稳压器 |
| 英文描述： | Fixed-Point Digital Signal Processor 532-FCBGA |
| 中文描述： | 0.75 A SWITCHING REGULATOR, 1600 kHz SWITCHING FREQ-MAX, PDSO16 |
| 封装： | QSOP-16 |
| 文件页数： | 13/20页 |
| 文件大小： | 371K |
| 代理商： | MAX1970EEE |
M
Dual, 180° Out-of-Phase, 1.4MHz, 750mA Step-
Down Regulator with POR and RSI/PFO
______________________________________________________________________________________
13
the PWM comparator
’
s inverting input. The PWM com-
parator turns off the internal high-side MOSFET when
this sum exceeds the integrated feedback voltage.
Current Limit
The internal MOSFET has a current limit of 1.2A (typ). If
the current flowing out of LX_ exceeds this maximum,
the high-side MOSFET turns off and the synchronous
rectifier MOSFET turns on. This lowers the duty cycle
and causes the output voltage to droop until the current
limit is no longer exceeded. There is also a synchro-
nous rectifier current limit of -0.85A. This is to protect
the device from current flowing into LX_. If the negative
current limit is exceeded, the synchronous rectifier is
turned off, and the inductor current continues to flow
through the high-side MOSFET body diode back to the
input until the beginning of the next cycle or until the
inductor current drops to zero.
V
CC
Decoupling
Due to the high-switching frequency and tight output
tolerance (±1%), decoupling between IN and V
CC
is
recommended. Connect a 10
resistor between IN and
V
CC
and a 0.1μF ceramic capacitor from V
CC
to GND.
Place the resistor and capacitor as close to V
CC
as
possible.
Startup
To reduce the supply inrush current, soft-start circuitry
ramps up the output voltage during startup. This is
done by charging the REF capacitor with a current
source of 25μA. Once REF reaches 1.2V, the output is
in full regulation. The soft-start time is determined from:
Soft-start occurs when power is first applied, and when
EN is pulled high with power already present. The part
also goes through soft-start when coming out of under-
voltage lockout (UVLO) or thermal shutdown. The range
of capacitor values for C
REF
is from 0.01μF to 1.0μF.
Undervoltage Lockout
If V
CC
drops below 2.35V, the MAX1970/MAX1971/
MAX1972 assume that the supply voltage is too low to
provide a valid output voltage, and the UVLO circuit
inhibits switching. Once V
CC
rises above 2.4V, the
UVLO is disabled and the soft-start sequence initiates.
Enable
A logic-enable input (EN) is provided. For normal oper-
ation, drive EN logic high. Driving EN low turns off both
outputs, and reduces the input supply current to
approximately 1μA.
Power-Fail Output
The input voltage is sensed for 5V (typical USB applica-
tions), and if V
CC
drops below 3.94V, the power-fail out-
put (PFO) goes high. The time from PFO going high to
the outputs going out of regulation depends on the oper-
ating output voltage and currents, and the upstream 5V
bus storage capacitor value, which is 120μF minimum
(per USB specification, version 2.0). The lower the oper-
ating voltages and currents, and the higher the storage
capacitor, the longer the elapsed time. PFO is an open-
drain output, and a 10k to 100k pullup resistor to V
CC
, or
either output, is recommended.
Power-On Reset
Power-on reset (
POR
) provides a system reset signal.
During power-up,
POR
is held low until both outputs
reach 92% of their regulated voltages,
POR
continues
to be held low for a delayed period, and then goes
high. This delay time (T
D
) for MAX1970 is 16.6ms. The
MAX1971 and MAX1972 have a delay of 175ms. Figure
2 is an example of a timing diagram.
The
POR
comparator is designed to be relatively
immune to short-duration negative-going output glitch-
es.The
Typical Operating Characteristics
gives a plot of
maximum transient duration vs.
POR
comparator over-
drive. The graph was generated using a negative-going
pulse applied to an output, starting at 100mV above the
actual
POR
threshold, dropping below the
POR
thresh-
old by the percentage indicated as comparator over-
drive, and then returning to 100mV above the
threshold. The graph indicates the maximum pulse
width the output transient can have without causing
POR
to trip low.
Reset Input
Reset input (RSI) is an input on the MAX1971 that,
when driven high, forces the
POR
to go low. When RSI
goes low,
POR
goes through a delay time identical to a
power-up event. See Figure 2 for timing diagram. RSI
allows software to command a system reset. RSI must
be high for a minimum period of 1μs in order to initiate
the
POR
.
Thermal-Overload Protection
Thermal-overload protection limits total power dissipa-
tion. When the IC
’
s junction temperature exceeds T
J
=
+170
°
C, a thermal sensor shuts down the device,
allowing the IC to cool. The thermal sensor turns the
part on again after the junction temperature cools by
20
°
C. This results in a pulsed output during continuous
overload conditions.
During a thermal event,
POR
goes low, PFO goes high,
and soft-start is reset.
t
V
I
C
C
SS
REF
REF
REF
REF
=
=
×
×
4.
10
4
相关PDF资料 |
PDF描述 |
|---|---|
| MAX1971 | Fixed-Point Digital Signal Processor 532-FCBGA |
| MAX1972 | Dual, 180∑ Out-of-Phase, 1.4MHz, 750mA Step- Down Regulator with POR and RSI/PFO |
| MAX1972EEE | Fixed-Point Digital Signal Processor 532-FCBGA |
| MAX1973 | Smallest 1A, 1.4MHz Step-Down Regulators |
| MAX1973EUB | Smallest 1A, 1.4MHz Step-Down Regulators |
相关代理商/技术参数 |
参数描述 |
|---|---|
| MAX1970EEE+ | 功能描述:直流/直流开关调节器 Dual 180 Out 1.4MHz 750mA Step-Down RoHS:否 制造商:International Rectifier 最大输入电压:21 V 开关频率:1.5 MHz 输出电压:0.5 V to 0.86 V 输出电流:4 A 输出端数量: 最大工作温度: 安装风格:SMD/SMT 封装 / 箱体:PQFN 4 x 5 |
| MAX1970EEE+T | 功能描述:直流/直流开关调节器 Dual 180 Out 1.4MHz 750mA Step-Down RoHS:否 制造商:International Rectifier 最大输入电压:21 V 开关频率:1.5 MHz 输出电压:0.5 V to 0.86 V 输出电流:4 A 输出端数量: 最大工作温度: 安装风格:SMD/SMT 封装 / 箱体:PQFN 4 x 5 |
| MAX1970EEE-T | 功能描述:直流/直流开关调节器 RoHS:否 制造商:International Rectifier 最大输入电压:21 V 开关频率:1.5 MHz 输出电压:0.5 V to 0.86 V 输出电流:4 A 输出端数量: 最大工作温度: 安装风格:SMD/SMT 封装 / 箱体:PQFN 4 x 5 |
| MAX19710ETN | 功能描述:ADC / DAC多通道 RoHS:否 制造商:Texas Instruments 转换速率: 分辨率:8 bit 接口类型:SPI 电压参考: 电源电压-最大:3.6 V 电源电压-最小:2 V 最大工作温度:+ 85 C 安装风格:SMD/SMT 封装 / 箱体:VQFN-40 |
| MAX19710ETN+ | 功能描述:ADC / DAC多通道 7.5Msps CODEC/AFE Full Duplex RoHS:否 制造商:Texas Instruments 转换速率: 分辨率:8 bit 接口类型:SPI 电压参考: 电源电压-最大:3.6 V 电源电压-最小:2 V 最大工作温度:+ 85 C 安装风格:SMD/SMT 封装 / 箱体:VQFN-40 |
发布紧急采购，3分钟左右您将得到回复。