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参数资料
| 型号： | MAX1798AEGP |
| 厂商： | MAXIM INTEGRATED PRODUCTS INC |
| 元件分类： | 基准电压源/电流源 |
| 英文描述： | Circular Connector; No. of Contacts:32; Series:MS27466; Body Material:Aluminum; Connecting Termination:Crimp; Connector Shell Size:19; Circular Contact Gender:Socket; Circular Shell Style:Wall Mount Receptacle RoHS Compliant: No |
| 中文描述： | FIVE OUTPUT, ADJUSTABLE POSITIVE LDO REGULATOR, CQCC20 |
| 封装： | 5 X 5 MM, 0.90 MM HEIGHT, QFN-20 |
| 文件页数： | 14/20页 |
| 文件大小： | 642K |
| 代理商： | MAX1798AEGP |
M
CDMA Cellular/PCS System
Power Supplies
14
______________________________________________________________________________________
Hard Shutdown
To shut down the MAX1798/MAX1798A/MAX1799/
MAX1799A, drive
OFF
low or allow the internal resistor
to pull down
OFF
while
ON
is high. The device shuts
down after the watchdog timer has cleared (35ms min,
52ms typ). During shutdown, all LDO outputs and
RSO
are actively pulled to GND, the open-drain drivers are
in a high-impedance state, and the serial port and reset
timer are inactive. Previously programmed output volt-
age data is retained in the internal registers as long as
V
IN1
> 2.1V. If the device is turned back on by the
ON
button, OUT1 automatically is enabled with the preshut-
down output voltage. OUT2
–
5 automatically return to
their preshutdown voltages once they are enabled
through the serial interface.
Soft Shutdown
The serial port can also be used to shut down the
MAX1798/MAX1798A/MAX1799/MAX1799A. Using the
control data byte to disable OUT1 will shut down the
entire device. Once shut down, the only means to turn
on the device is through a momentary low on the
ON
button.
Control Data Byte
The control data byte is 8 bits long (3 command bits
and 5 data bits). The first 3 bits specify the action to be
taken, while the last 5 bits set the output voltage or
ON/OFF status. Each regulator has an individual DAC
that sets the output voltage. The DAC registers are
double buffered to allow for simultaneous updating of
all outputs. The output voltage is programmed per
Table 2 or Table 3. At power-up, if no specific voltage
is programmed, OUT1
–
5 will be set for 2.98V. All DAC
programming must be shifted from the double buffer to
the DACs with the update DAC command (Table 1,
000XXXXX) for the programmed voltages to be seen at
the LDO outputs. The DACs can be updated one at a
time or all at once after all desired outputs are pro-
grammed. The ON/OFF status of the LDOs and drivers
is not double-buffered and takes immediate effect upon
CS
returning high (SPI compatible) or upon the ninth
rising edge of SCK during the command byte (Figure 2,
edge L). A one turns on the LDO output or driver out-
put, and a zero turns it off.
SPI-Compatible Serial Interface
Use an SPI-compatible 3-wire serial interface with the
MAX1798/MAX1798A to control the ON/OFF state and
output voltage of each regulator, the ON/OFF state of
the drivers, and to shut down the device. Figures 4a
and 4b are timing diagrams for the SPI protocol. The
MAX1798/MAX1798A is a write-only device and uses
CS
along with SCLK and DIN to communicate. The seri-
al port operates when the device is enabled, even when
RSO
is low. The MAX1798/MAX1798A can support a
2MHz (max) data rate. This SPI-compatible port uses
the CPOL = CPHA = 0 protocol.
I
2
C-Compatible Serial Interface
Use an I
2
C-compatible 2-wire serial interface with the
MAX1799/MAX1799A to control the ON/OFF state and
output voltage of each regulator, the ON/OFF state of
the drivers, and to shut down the device. Use standard
I
2
C-compatible write-byte commands to program the
IC. Figure 2 is a timing diagram for the I
2
C protocol.
The MAX1799/MAX1799A is always a slave to the bus
master. The serial port operates when the device is
enabled, even when OUT1 and
RSO
are low. When AS
is high, the address is 0111111. When AS is low, the
address is 1001111. Two MAX1799/MAX1799A devices
can be controlled by a single bus master.
Output Voltage
The MAX1798/MAX1798A/MAX1799/MAX1799A are
supplied with factory-set output voltages. At power-up,
all DACS are set for 2.98V, while only OUT1 is enabled;
all other LDO outputs and drivers are off. OUT2
–
5,
DR1, and DR2 must be enabled on with the serial port.
OUT2
–
5 can be individually programmed through the
serial port from 1.8V to 3.3V in 32 steps, either while on
or off. OUT1 can be programmed in 32 steps from 1.8V
to 3.3V only while on. (If OUT1 is off, the serial port is
also off, and OUT1 cannot be programmed.) If OUT1 is
turned off through the serial port or the
OFF
pin, the
entire chip, including the serial port, will be shut down.
However, all previously programmed DAC settings will
be retained as long as a valid supply voltage is main-
tained on IN1 (V
IN1
> 2.1V).
Current Limit
The MAX1798/MAX1798A/MAX1799/MAX1799A
include current limiting on each LDO output. OUT1 has
a current limit set at 500mA (320mA min), while
OUT2
–
5 have current limits set at 250mA (160mA min).
When the LDO output is in current limit, the current-lim-
iter device monitors and controls the pass transistor
’
s
gate voltage, limiting the output current available from
the LDO. Once the excessive load is removed, normal
function resumes automatically.
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相关代理商/技术参数 |
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| MAX1798AETP | 制造商:Rochester Electronics LLC 功能描述: 制造商:Maxim Integrated Products 功能描述: |
| MAX1798AEUP | 功能描述:PMIC 解决方案 CDMA Cellular/PCS System Power Supply RoHS:否 制造商:Texas Instruments 安装风格:SMD/SMT 封装 / 箱体:QFN-24 封装:Reel |
| MAX1798AEUP-T | 功能描述:PMIC 解决方案 CDMA Cellular/PCS System Power Supply RoHS:否 制造商:Texas Instruments 安装风格:SMD/SMT 封装 / 箱体:QFN-24 封装:Reel |
| MAX1798EGP | 功能描述:PMIC 解决方案 RoHS:否 制造商:Texas Instruments 安装风格:SMD/SMT 封装 / 箱体:QFN-24 封装:Reel |
| MAX1798EGP+ | 功能描述:PMIC 解决方案 CDMA Cellular/PCS System Power Supply RoHS:否 制造商:Texas Instruments 安装风格:SMD/SMT 封装 / 箱体:QFN-24 封装:Reel |
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