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MAX782CBX 参数 Datasheet PDF下载

MAX782CBX图片预览
型号: MAX782CBX
PDF下载: 下载PDF文件 查看货源
内容描述: 三输出电源控制器,用于笔记本电脑 [Triple-Output Power-Supply Controller for Notebook Computers]
分类和应用: 电脑控制器
文件页数/大小: 32 页 / 497 K
品牌: MAXIM [ MAXIM INTEGRATED PRODUCTS ]
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Trip le -Ou t p u t P o w e r-S u p p ly  
Co n t ro lle r fo r No t e b o o k Co m p u t e rs  
To t a l S h u t d o w n Circ u it s  
When the +5V and +3.3V supplies are off, the complete  
(+5.5V TO +18V)  
BATT  
V
MAX782 circuit consumes only about 70µA, plus any  
leakage through the off MOSFETs. Some NiCd batter-  
ies can be damaged if they are fully discharged and  
then left for long periods (months) under load. Even  
100µA can do damage if left long enough.  
CD4011B  
1N4148  
ON/  
OFF  
S
ON  
1M  
The complete power-supply system can be shut down  
by taking ON5 low, cutting the supply to the MAX782s  
V+ pin, while the bootstrapped +5V supply is turned  
off. This removes the supply from the controller, and  
turns off all the supplies. In this condition, the current  
consumption drops to the level of the leakage currents  
in the off transistors. Switching the V+ supply off is  
e a s y b e c a us e the V+ line d ra ws ve ry little p owe r;  
switching the entire power input from the battery would  
be more difficult.  
MAX782  
1M  
1M  
1µF  
ZETEX  
ZVP2106G  
SOT 223  
ON  
R
1N4148  
1M  
V+  
1N4148  
1M  
1µF  
VL  
Q1  
2N4401  
OFF  
MAX782  
R1  
1M  
ON5  
Figure 12 shows a logic interface for a momentary  
switch that toggles the whole system on and off. The  
logic circuit runs from the battery supply, so the input  
voltage from the battery is limited to the normal operat-  
ing range for the flip-flop gates, which is usually 18V for  
4000-series CMOS circuits. The active-high OFF input  
permits the supplies to be turned off under logic control  
as well as when the switch is pushed. If this logic input  
is not required, omit R1 and Q1. The supplies can only  
be turned on using the hardware switch. For automatic  
turn-off, connect the OFF input to a battery-voltage  
sensing comparator or to a timer powered from VL.  
Ensure that any signal connected to OFF does not  
glitch high at power-up.  
PGND  
1N4148  
ON5  
Figure 12. Hardware/Software Total Shutdown Circuit  
Q1  
2N4403  
VDD  
OUT  
FROM MAX782  
C1  
100nF  
R4  
1k  
C3  
10nF  
R1  
16.9k  
C2  
6.8µF  
Ge n e ra t in g Ad d it io n a l VP P Ou t p u t s  
Us in g Ex t e rn a l Lin e a r Re g u la t o rs  
R2  
6.34k  
3
2
7
Fig ure 13 s hows a low-d rop out line a r re g ula tor  
designed to provide an additional VPP output from the  
VDD line. It can be turned off with a logic-level signal;  
its output can be switched to 5V or 12V; and it pro-  
vides excellent rejection of the high-frequency noise  
on VDD. If a monolithic line a r re g ula tor is us e d ,  
c hoos e one ha ving g ood PSRR p e rforma nc e a t  
300kHz.  
U1  
OP27  
6
FROM MAX782  
REF  
4
R3  
26.7k  
R5  
100k  
C4  
10nF  
Q3  
2N7002  
OFF/ON  
12/5  
Q2  
2N7002  
OFF/ON  
12/5  
V
OUT  
(V)  
1
0
0
X
0
1
0
5
12  
X = DON'T CARE  
Figure 13. External Regulator For Additional VPP Outputs  
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