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參數資料
| 型號： | MAX685EEE+ |
| 廠商： | MAXIM INTEGRATED PRODUCTS INC |
| 元件分類： | 穩(wěn)壓器 |
| 英文描述： | Dual-Output (Positive and Negative), DC-DC Converter for CCD and LCD |
| 中文描述： | 0.44 A DUAL SWITCHING CONTROLLER, 480 kHz SWITCHING FREQ-MAX, PDSO16 |
| 封裝： | 0.150 INCH, 0.025 INCH PITCH, QSOP-16 |
| 文件頁數： | 8/11頁 |
| 文件大?。?/td> | 344K |
| 代理商： | MAX685EEE+ |
_______________Detailed Description
The MAX685 DC-DC converter accepts an input voltage
between +2.7V and +5.5V and generates both a positive
and negative voltage, using a single inductor (Figure 1).
It alternates between acting as a step-up converter and
as an inverting converter on a cycle-by-cycle basis. Both
output voltages are independently regulated.
Each output is separately controlled by a pulse-width-
modulated (PWM) current mode regulator. This allows
the part to operate at a fixed frequency for use in noise-
sensitive applications. An internal oscillator runs at
220kHz or 400kHz, or can be synchronized to an exter-
nal signal. Since switching alternates between the two
regulators, each operates at half the oscillator frequency
(110kHz, 200kHz, or half the sync frequency). The oscil-
lator can be synchronized to a 200kHz to 480kHz clock.
On the first cycle of operation, the part operates as a
step-up converter. LXP connects to VDD, LXN pulls to
ground, and the inductor current rises. Once the induc-
tor current rises to a level set by the positive-side error
amplifier, LXN releases and the inductor current flows
through D2 to the positive output. When the inductor
current drops to zero (which happens each cycle under
normal, discontinuous operation), LXN returns to the
input voltage.
On the second cycle, LXN is held at ground. LXP is
pulled up to the input voltage until the current reaches
the limit set by the negative error amplifier. Then LXP is
released and the inductor current flows through D1 to
the negative output. Once the inductor current reaches
zero, the voltage at LXP returns to ground. The wave-
forms at LXN and LXP are shown in Figure 2 for a typi-
cal pair of cycles.
MAX685
Dual-Output (Positive and Negative),
DC-DC Converter for CCD and LCD
6
_______________________________________________________________________________________
Pin Description
PIN
16-QSOP
P-Channel Switching Inductor Node. LXP turns off when the part enters shutdown.
LXP
1
FUNCTION
NAME
Internally Connected. Do not externally connect.
I.C.
2, 15
Open-Drain Power-OK Output. POK is high when both outputs are in regulation. Connect POK
to VDD with a 100k
pull-up resistor to VDD.
POK
4
Power Input. Connect to VDD.
VP
3
Shutdown Input. Both outputs go to 0V in shutdown. Connect to VDD for automatic startup.
SHDN
6
Supply Input. Bypass VDD with a 1.0F or greater ceramic capacitor to GND.
VDD
8
Sync Input. This pin synchronizes the oscillator to an external clock frequency between 200kHz
and 480kHz. Connect SYNC to GND (220kHz) or VDD (400kHz) for internal oscillator frequency.
SYNC
7
Power-Up Sequence Select Input. Connect SEQ to GND to power the negative output voltage
first. Connect SEQ to VDD to power the positive output first.
SEQ
5
Ground
GND
9
1.25V Reference Voltage Output. Bypass with 0.22F to GND.
REF
11
Power Ground. Connect PGND to GND.
PGND
13, 14
Feedback for the Positive Output Voltage. Connect a resistor-divider between the positive out-
put and GND with the center to FBP to set the positive output voltage.
FBP
12
Feedback Input for the Negative Output Voltage. Connect a resistor-divider between the nega-
tive output and REF with the center to FBN to set the negative output voltage.
FBN
10
N-Channel Switching Inductor Node. LXN pulls to GND through the internal transistor when the
part is shut down.
LXN
16
This pin in not internally connected.
N.C.
—
19, 24
4
2, 3
6
8
7
5
11
13
15, 16, 17
14
PIN
24-TQFN
12
22, 23
20, 21
1, 9, 10,
18
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| MAX685EEE+T | Dual-Output (Positive and Negative), DC-DC Converter for CCD and LCD |
| MAX685ETG+ | Dual-Output (Positive and Negative), DC-DC Converter for CCD and LCD |
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| MAXQ612G-0000+ | 16-BIT, FLASH, 12 MHz, RISC MICROCONTROLLER, PQFP64 |
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相關代理商/技術參數 |
參數描述 |
|---|---|
| MAX685EEE+ | 功能描述:直流/直流開關轉換器 DC/DC Converter for CCD & LCD RoHS:否 制造商:STMicroelectronics 最大輸入電壓:4.5 V 開關頻率:1.5 MHz 輸出電壓:4.6 V 輸出電流:250 mA 輸出端數量:2 最大工作溫度:+ 85 C 安裝風格:SMD/SMT |
| MAX685EEE+T | 功能描述:直流/直流開關轉換器 DC/DC Converter for CCD & LCD RoHS:否 制造商:STMicroelectronics 最大輸入電壓:4.5 V 開關頻率:1.5 MHz 輸出電壓:4.6 V 輸出電流:250 mA 輸出端數量:2 最大工作溫度:+ 85 C 安裝風格:SMD/SMT |
| MAX685EEE-T | 功能描述:直流/直流開關轉換器 DC/DC Converter for CCD & LCD RoHS:否 制造商:STMicroelectronics 最大輸入電壓:4.5 V 開關頻率:1.5 MHz 輸出電壓:4.6 V 輸出電流:250 mA 輸出端數量:2 最大工作溫度:+ 85 C 安裝風格:SMD/SMT |
| MAX685ETG | 功能描述:直流/直流開關轉換器 RoHS:否 制造商:STMicroelectronics 最大輸入電壓:4.5 V 開關頻率:1.5 MHz 輸出電壓:4.6 V 輸出電流:250 mA 輸出端數量:2 最大工作溫度:+ 85 C 安裝風格:SMD/SMT |
| MAX685ETG+ | 功能描述:直流/直流開關轉換器 DC/DC Converter for CCD & LCD RoHS:否 制造商:STMicroelectronics 最大輸入電壓:4.5 V 開關頻率:1.5 MHz 輸出電壓:4.6 V 輸出電流:250 mA 輸出端數量:2 最大工作溫度:+ 85 C 安裝風格:SMD/SMT |
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