MAX8734A datasheet(21/33 Pages) MAXIM

Nome de Peças	MAX8734A

Descrição Electrónicos	High-Efficiency, Quad-Output, Main Power-Supply Controllers for Notebook Computers

Download	33 Pages

Scroll/Zoom	100%

Fabricante Electrônico	MAXIM [Maxim Integrated Products]

Página de início	https://www.maximintegrated.com/en.html

Logo

21 / 33 page

High-Efficiency, Quad-Output, Main Power-

Supply Controllers for Notebook Computers

______________________________________________________________________________________

21

undervoltage-protection circuit, this current-limit

method is effective in almost every circumstance.

A negative current limit prevents excessive reverse

inductor currents when VOUT sinks current. The nega-

tive current-limit threshold is set to approximately 120%

of the positive current limit and therefore tracks the

positive current limit when ILIM_ is adjusted.

The current-limit threshold is adjusted with an external

voltage-divider at ILIM_. The current-limit threshold

adjustment range is from 50mV to 300mV. In the

adjustable mode, the current-limit threshold voltage is

precisely 1/10th the voltage at ILIM_. The threshold

defaults to 100mV when ILIM_ is connected to VCC.

The logic threshold for switchover to the 100mV default

value is approximately VCC - 1V.

Carefully observe the PC board layout guidelines to

ensure that noise and DC errors do not corrupt the cur-

rent-sense signals at CS_. Mount or place the device

close to the synchronous rectifier or sense resistor

(whichever is used) with short, direct traces, making a

Kelvin-sense connection to the sense resistor. The cur-

rent-sense accuracy of Figure 8 is degraded if the

Schottky diode conducts during the synchronous recti-

fier on-time. To ensure that all current passes through

the sense resistor, connect the Schottky diode in paral-

lel with only the synchronous rectifier (Figure 9) if the

voltage drop across the synchronous rectifier and

sense resistor exceeds the Schottky diode’s forward

voltage. Note that at high temperatures, the on-resis-

tance of the synchronous rectifier increases and the

forward voltage of the Schottky diode decreases.

MOSFET Gate Drivers (DH_, DL_)

The DH_ and DL_ gate drivers sink 2.0A and 3.3A,

respectively, of gate drive, ensuring robust gate drive for

high-current applications. The DH_ floating high-side

MOSFET drivers are powered by diode-capacitor charge

pumps at BST_. The DL_ synchronous-rectifier drivers are

powered by LDO5.

The internal pulldown transistors that drive DL_ low

have a 0.6

Ω typical on-resistance. These low on-resis-

tance pulldown transistors prevent DL_ from being

pulled up during the fast rise time of the inductor nodes

due to capacitive coupling from the drain to the gate of

the low-side synchronous-rectifier MOSFETs. However,

for high-current applications, some combinations of

high- and low-side MOSFETS may cause excessive

gate-drain coupling, which leads to poor efficiency and

EMI-producing shoot-through currents. Adding a resis-

tor in series with BST_ increases the turn-on time of the

MAX8732A

MAX8733A

V+

DH_

DL_

CS_

LX_

OUT_

Figure 8. Current Sensing Using Sense Resistor

(MAX8732A/MAX8733A)

MAX8732A

MAX8733A

V+

DH_

DL_

CS_

LX_

OUT_

Figure 9. More Accurate Current Sensing with Adjusted

Schottky Connection

MAX8732A

MAX8733A

MAX8734A

5V

VIN

10

Ω

BST

DH

LX

Figure 10. Reducing the Switching-Node Rise Time

Nº de peça semelhante - MAX8734A

Fabricante Electrônico	Nome de Peças	Folha de dados	Descrição Electrónicos
Maxim Integrated Produc...	MAX8734	1Mb / 32P	High-Efficiency, Quad-Output, Main Power-Supply Controllers for Notebook Computers Rev 0; 8/04
Maxim Integrated Produc...	MAX8734EEI	1Mb / 32P	High-Efficiency, Quad-Output, Main Power-Supply Controllers for Notebook Computers Rev 0; 8/04

More results

Descrição semelhante - MAX8734A

Fabricante Electrônico	Nome de Peças	Folha de dados	Descrição Electrónicos
Maxim Integrated Produc...	MAX17003	610Kb / 36P	High-Efficiency, Quad-Output, Main Power-Supply Controllers for Notebook Computers 19-0765; Rev 0; 3/07
Maxim Integrated Produc...	MAX17003ETJ	610Kb / 36P	High-Efficiency, Quad-Output, Main Power-Supply Controllers for Notebook Computers Rev 0; 3/07
Intersil Corporation	ISL6236A	3Mb / 37P	High-Efficiency, Quad-Output, Main Power Supply Controllers for Notebook Computers
Maxim Integrated Produc...	MAX17003A	617Kb / 36P	High-Efficiency, Quad-Output, Main Power- Supply Controllers for Notebook Computers Rev 0; 6/07
Maxim Integrated Produc...	MAX8732	1Mb / 32P	High-Efficiency, Quad-Output, Main Power-Supply Controllers for Notebook Computers Rev 0; 8/04
Renesas Technology Corp	ISL6236A	3Mb / 37P	High-Efficiency, Quad-Output, Main Power Supply Controllers for Notebook Computers
Renesas Technology Corp	ISL6236	3Mb / 36P	High-Efficiency, Quad-Output, Main Power Supply Controllers for Notebook Computers
Intersil Corporation	ISL6237	2Mb / 35P	High-Efficiency, Quad-Output, Main Power Supply Controllers for Notebook Computers
Maxim Integrated Produc...	MAX8744A	607Kb / 36P	High-Efficiency, Quad Output, Main Power- Supply Controllers for Notebook Computers Rev 0; 6/07
Renesas Technology Corp	ISL6237	3Mb / 35P	High-Efficiency, Quad-Output, Main Power Supply Controllers for Notebook Computers

More results

MAX8734A Folha de dados(PDF) 21 Page - Maxim Integrated Products

MAX8734A Folha de dados(HTML) 21 Page - Maxim Integrated Products

Nº de peça semelhante - MAX8734A

Descrição semelhante - MAX8734A

Html Pages

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33

Folha de dados Download

Ligação URL