- 您现在的位置：买卖IC网 > PDF目录1841 > MAX1878ETC+ (Maxim Integrated Products)IC REG BUCK BST SYNC ADJ 12TQFN PDF资料下载
参数资料
| 型号： | MAX1878ETC+ |
| 厂商： | Maxim Integrated Products |
| 文件页数： | 8/12页 |
| 文件大小： | 0K |
| 描述： | IC REG BUCK BST SYNC ADJ 12TQFN |
| 产品培训模块： | Lead (SnPb) Finish for COTS Obsolescence Mitigation Program |
| 标准包装： | 75 |
| 类型： | 降压（降压），升压（升压） |
| 输出类型： | 可调式 |
| 输出数： | 2 |
| 输出电压： | 1.25 V ~ 28 V |
| 输入电压： | 2 V ~ 5.5 V |
| PWM 型： | 电压模式 |
| 频率 - 开关： | 500kHz |
| 电流 - 输出： | 500mA |
| 同步整流器： | 是 |
| 工作温度： | -40°C ~ 85°C |
| 安装类型： | 表面贴装 |
| 封装/外壳： | 12-WQFN 裸露焊盘 |
| 包装： | 管件 |
| 供应商设备封装： | 12-TQFN-EP（4x4） |
Dual-Output Step-Down and LCD Step-Up
Power Supply for PDAs
current, resulting in increased efficiency and reduced
output voltage ripple. When delivering medium and
higher output currents, the MAX1878 extends either the
on-time or the off-time, as necessary to maintain regula-
tion, resulting in nearly constant frequency operation
with high efficiency and low output voltage ripple.
Step-Up Converter Control Scheme
The MAX1878 step-up converter features a minimum
off-time, current-limited control scheme. The duty cycle
is governed by a pair of one-shots that set a minimum
off-time and a maximum on-time. The switching fre-
quency can be up to 500kHz and depends upon the
load and input voltage. The peak current limit of the
internal N-channel MOSFET is 280mA.
On/Off Control
Pulling ON low places the MAX1878 step-down con-
verter in shutdown mode and reduces step-down con-
verter supply current to less than 1μA. In shutdown, the
internal switching MOSFETs and synchronous rectifier
turn off and LX goes high impedance.
Pulling ONLCD low places the MAX1878 step-up con-
verter in shutdown mode and reduces step-up convert-
er supply current to less than 1μA. In shutdown, LXLCD
enters a high-impedance state and the output remains
connected to the input through the inductor and rectifi-
er holding the output voltage to a diode drop below
V IN . The LCD output capacitance and load determine
the rate at which V LCD decays. Connect ON and
ONLCD to IN for normal operation.
Soft-Start
The MAX1878 internal soft-start circuitry limits current
drawn at startup, reducing transients on the input source.
Soft-start is particularly useful for higher impedance input
sources, such as lithium ion and alkaline cells. Step-down
converter soft-start is implemented with current limit. At
startup the step-down converter current limit is set to 25%
of its full current limit. The current limit is increased by
25% every 256 switching cycles until full current limit is
reached. Step-up converter soft-start is implemented with
LXLCD minimum off-time. At startup the LXLCD minimum
off-time is 2.6μs allowing the LCD output voltage to build
up gradually. When the output reaches approximately
80% of its final output voltage the LXLCD minimum off-
time is decreased to its final value of 1μs. See Soft-Start
and Shutdown Response in the Typical Operating
Characteristics section.
V IN
2.0V TO 3.3V*
L2
10 μ H*
D1
LCD OUTPUT
UP TO 28V
TWO SERIES
ALKALINE CELLS
C1
10 μ F
1
IN
LXLCD
9
C5
5pF
R3
3.6M Ω
C3
0.1 μ F
R5
10 Ω
3
AIN1
FBLCD
6
R4
270k Ω
C2
1 μ F
4
AIN2
MAX1878
LX
2
L1
10 μ H
MAIN OUTPUT
1.25V TO V IN
MAIN
LCD
OFF
OFF
ON
ON
7
10
ON
ONLCD
FB
R6
2M Ω
5
C6
20pF
R1
28k Ω
C4
22 μ F
R2
63.4k Ω
PGND
12
*FOR INPUT VOLTAGES GREATER THAN 3.3V USE A HIGHER
VALUE INDUCTOR L2. SEE INDUCTOR SELECTION
Figure 1. MAX1878 Standard Application Circuit
AGND PGNDLCD
8 11
8
_______________________________________________________________________________________
相关PDF资料 |
PDF描述 |
|---|---|
| MAX1879EUA+T | IC CHARGER LI+ PULSE 8UMAX |
| MAX1880EUG+ | IC DC-DC CONV QUAD LCD 24TSSOP |
| MAX1889ETE+T | IC PWR SUP TRPL LCD 16-TQFN |
| MAX1896EUT#TG16 | IC REG BOOST ADJ 0.5A SOT23-6 |
| MAX1897ETP+T | IC REG CTRLR BUCK PWM 20-TQFN |
相关代理商/技术参数 |
参数描述 |
|---|---|
| MAX1878ETC+ | 功能描述:直流/直流开关转换器 Dual-Output Step-Down RoHS:否 制造商:STMicroelectronics 最大输入电压:4.5 V 开关频率:1.5 MHz 输出电压:4.6 V 输出电流:250 mA 输出端数量:2 最大工作温度:+ 85 C 安装风格:SMD/SMT |
| MAX1878ETC+T | 功能描述:直流/直流开关转换器 Dual-Output Step-Down RoHS:否 制造商:STMicroelectronics 最大输入电压:4.5 V 开关频率:1.5 MHz 输出电压:4.6 V 输出电流:250 mA 输出端数量:2 最大工作温度:+ 85 C 安装风格:SMD/SMT |
| MAX1878EVKIT | 功能描述:直流/直流开关转换器 Evaluation Kit for the MAX1878 RoHS:否 制造商:STMicroelectronics 最大输入电压:4.5 V 开关频率:1.5 MHz 输出电压:4.6 V 输出电流:250 mA 输出端数量:2 最大工作温度:+ 85 C 安装风格:SMD/SMT |
| MAX1879EUA | 功能描述:电池管理 1-Cell Li+ Pulse Charger RoHS:否 制造商:Texas Instruments 电池类型:Li-Ion 输出电压:5 V 输出电流:4.5 A 工作电源电压:3.9 V to 17 V 最大工作温度:+ 85 C 最小工作温度:- 40 C 封装 / 箱体:VQFN-24 封装:Reel |
| MAX1879EUA+ | 功能描述:电池管理 1-Cell Li+ Pulse Charger RoHS:否 制造商:Texas Instruments 电池类型:Li-Ion 输出电压:5 V 输出电流:4.5 A 工作电源电压:3.9 V to 17 V 最大工作温度:+ 85 C 最小工作温度:- 40 C 封装 / 箱体:VQFN-24 封装:Reel |
发布紧急采购，3分钟左右您将得到回复。