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參數(shù)資料
| 型號： | MAX847EEI |
| 廠商： | MAXIM INTEGRATED PRODUCTS INC |
| 元件分類： | 電源管理 |
| 英文描述： | 1-Cell, Step-Up Two-Way Pager System IC |
| 中文描述： | 1-CHANNEL POWER SUPPLY MANAGEMENT CKT, PDSO28 |
| 封裝： | 0.150 INCH, 0.025 INCH PITCH, QSOP-28 |
| 文件頁數(shù)： | 11/18頁 |
| 文件大?。?/td> | 167K |
| 代理商： | MAX847EEI |
The comparison threshold voltages for each channel
are described in the following equations:
V
TH
(CH0: pin 9) = D
·
10mV
V
TH
(CH1: NICD) = D
·
40mV
V
TH
(CH2: BATT) = D
·
10mV
where D is the decimal equivalent of the binary code
DAC0–DAC6 (Table 2). DAC0 is the LSB. A DAC code
of 1111111 equates to D = 127. When all zeros are pro-
grammed, the CH DAC and CH_ comparators turn off.
CH0, CH1, and CH2 comparison results reside in the
three MSB locations of the output serial data (Table 5).
The CH_ OUT data is delayed by one read cycle. In
other words, each CH_ OUT bit is the result of the com-
parison made against the CH DAC voltage pro-
grammed during the previous serial-write operation.
An analog-to-digital (A/D) conversion can be performed
on a channel by using the system software to step
through a successive-approximation routine or, if the
input is partially known, by setting the CH DAC to a
voltage near the estimated point and checking succes-
sive CH_ OUT bits.
A faster A/D shortcut can be used for battery measure-
ments when the goal is a “go, no go” determination. For
this type of test, the CH DAC can simply be set to the
desired limit, and CH_ OUT supplies the result on the
next serial-write operation. One instance in which this
shortcut saves time is during a battery-impedance
check. The unloaded battery voltage can first be mea-
sured, if time allows, using one of the techniques
described in the previous paragraph. Then the magni-
tude of the loaded voltage drop can be quickly checked
with a single comparison to see if it is within the desired
limit.
The A/D circuitry can be invoked in both Run and Coast
Mode.
Open-Drain Drivers
Two open-drain drivers (DR1 and DR2) are activated
via the serial interface. DR1 and DR2 are grounded
1.8
(typical) NFETs that can sink up to 120mA. The
maximum sink current is limited by on-resistance and
package dissipation to about 240mA total sink current
for both switches. Note that DR1 and DR2 are designed
to sink current only from the main battery (BATT) and
cannot be pulled above BATT.
DR2 is controlled by an external input (DR2IN) as well
as a serial input bit. DR2IN is ANDed with the DR2ON
serial-control bit, allowing DR2 to drive an audio beep-
er. The audio-frequency clock is applied to DR2IN, and
ON/OFF gating is applied to DR2ON. Both DR2IN (pin
18) and DR2ON (serial bit) must be high for DR2 to
switch on. DR1 is controlled only by DR1ON (serial bit).
Run and Coast Modes
The MAX847’s default mode is Coast. Run Mode is
selected by either serial command (Table 2) or by
pulling the RUN pin high. The RUN serial bit and the
RUN pin are logically ORed. Both must be low to imple-
ment Coast Mode. In Coast Mode, the DC-DC convert-
er pulses only as needed to satisfy the load, holding
MAX847 operating current to typically 13μA. In Run
Mode the DC-DC converter employs fixed-frequency
M
1-Cell, S tep-Up
Two-Way Pager S ystem IC
______________________________________________________________________________________
11
Table 1. Run and Coast Mode Start-Up Requirements
SYNC OPERATION
CIRCUIT CONNECTION
START-UP MODE CAPABILITY
No SYNC clock is used.
1) Connect REF to FILT
2) Remove R7, C9, and C10
Can start in either Coast or Run Mode
by tying RUN pin appropriately. In Run
Mode the DC-DC converter operates at
270kHz.
On initial power-up, system can supply
SYNC clock to MAX847 when REG1 is
greater than 1.5V.
Use standard Figure 2 circuit
Can start in either Coast or Run Mode
by tying RUN pin appropriately. In Run
Mode the DC-DC converter operates at
7f
SYNC
once the SYNC clock is applied.
On initial power-up, system can supply
SYNC clock to MAX847 before, or
concurrent with, RSO going high.
Add Q1 as shown in Figure 3
Can start in either Coast or Run Mode
by tying RUN pin appropriately. In Run
Mode the DC-DC converter operates at
7f
SYNC
once the SYNC clock is applied.
On start-up, system does not supply
SYNC clock to MAX847 until after RSO
goes high.
Use standard Figure 2 circuit
Must start in Coast Mode. Run Mode may
then be started by the system after start-up.
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相關(guān)代理商/技術(shù)參數(shù) |
參數(shù)描述 |
|---|---|
| MAX847EEI+ | 功能描述:電池管理 1 Cell Step-Up 2-Way Pager System IC RoHS:否 制造商:Texas Instruments 電池類型:Li-Ion 輸出電壓:5 V 輸出電流:4.5 A 工作電源電壓:3.9 V to 17 V 最大工作溫度:+ 85 C 最小工作溫度:- 40 C 封裝 / 箱體:VQFN-24 封裝:Reel |
| MAX847EEI+T | 功能描述:電池管理 1 Cell Step-Up 2-Way Pager System IC RoHS:否 制造商:Texas Instruments 電池類型:Li-Ion 輸出電壓:5 V 輸出電流:4.5 A 工作電源電壓:3.9 V to 17 V 最大工作溫度:+ 85 C 最小工作溫度:- 40 C 封裝 / 箱體:VQFN-24 封裝:Reel |
| MAX847EEI-C70955 | 制造商:Rochester Electronics LLC 功能描述: 制造商:Maxim Integrated Products 功能描述: |
| MAX847EEI-T | 功能描述:電池管理 1 Cell Step-Up 2-Way Pager System IC RoHS:否 制造商:Texas Instruments 電池類型:Li-Ion 輸出電壓:5 V 輸出電流:4.5 A 工作電源電壓:3.9 V to 17 V 最大工作溫度:+ 85 C 最小工作溫度:- 40 C 封裝 / 箱體:VQFN-24 封裝:Reel |
| MAX847EVKIT | 制造商:Maxim Integrated Products 功能描述:1-CELL STEP-UP TWO-WAY PAGER SYSTE - Rail/Tube |
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