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PDF BD3509MUV Data sheet ( Hoja de datos )
| Número de pieza | BD3509MUV | |
| Descripción | Nch FET Ultra LDO | |
| Fabricantes | ROHM Semiconductor | |
| Logotipo |  |
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High Performance Regulators for PCs
Nch FET Ultra LDO for PC Chipsets
BD3508MUV
Nch FET Ultra LDO for PC Chipsets
with Power Good
BD3509MUV
No.10030ECT22
●Description
The BD3508MUV / BD3509MUV ultra low-dropout linear chipset regulator operates from a very low input supply, and offers
ideal performance in low input voltage to low output voltage applications. It incorporates a built-in N-MOSFET power
transistor to minimize the input-to-output voltage differential to the ON resistance (RON MAX=100mΩ/50mΩ) level. By
lowering the dropout voltage in this way, the regulator realizes high current output (Iomax=3.0A/4.0A) with reduced
conversion loss, and thereby obviates the switching regulator and its power transistor, choke coil, and rectifier diode. Thus,
the BD3508MUV / BD3509MUV are designed to enable significant package profile downsizing and cost reduction. An
external resistor allows the entire range of output voltage configurations between 0.65 and 2.7V, while the NRCS (soft start)
function enables a controlled output voltage ramp-up, which can be programmed to whatever power supply sequence is
required.
●Features
1) Internal high-precision reference voltage circuit (0.65V±1%)
2) Built-in VCC under voltage lock out circuit (VCC=3.80V)
3) NRCS (soft start) function reduces the magnitude of in-rush current
4) Internal Nch MOSFET driver offers low ON resistance (65mΩ/28mΩ typ)
5) Built-in current limit circuit (3.0A/4.0A min)
6) Built-in thermal shutdown (TSD) circuit
7) Variable output (0.65～2.7V)
8) Incorporates high-power VQFN020V4040 package: 4.0×4.0×1.0(mm)
9) Tracking function
●Applications
Notebook computers, Desktop computers, LCD-TV, DVD, Digital appliances
●Model Lineup
Maximum output current
3A
4A
Package
VQFN020V4040
VCC=5V
BD3508MUV
BD3509MUV
www.rohm.com
© 2010 ROHM Co., Ltd. All rights reserved.
1/20
2010.04 - Rev.C
1 page  
BD3508MUV,BD3509MUV
●Reference Data
BD3508MUV
Vo
50mV/div
45mV
Vo
50mV/div
Io
2A/div
3.0A
Io
2A/div
64mV
3.0A
Technical Note
Vo
100mV/div
Io
2A/div
91mV
3A
Io=0A→3A/3µsec t(5µsec/div)
Fig.1 Transient Response
(0→3A)
Co=150µF×2, CFB=0.01uF
Io=0A→3A/3µsec t(5µsec/div)
Fig.2 Transient Response
(0→3A)
Co=150µF
Vo
50mV/div
55mV
Vo
50mV/div
79mV
Io
2A/div
3.0A
Io
2A/div 3.0A
Io=0A→3A/3µsec t(5µsec/div)
Fig.3 Transient Response
(0→3A)
Co=47µF, CFB=0.01uF
Vo
100mV/div
87mV
Io
2A/div
3A
Io=3A→0A/3µsec t(5µsec/div)
Fig.4 Transient Response
(3→0A)
Co=150µF×2
Io=3A→0A/3µsec t(5µsec/div)
Fig.5 Transient Response
(3→0A)
Co=150µF
Ven
2V/div
Ven
2V/div
VNRCS
2V/div
Vo
1V/div
t(200µsec/div)
Fig.7: Waveform at output start
VNRCS
2V/div
Vo
1V/div
t(2msec/div)
Fig.8 Waveform at output OFF
Io=3A→0A/3µsec t(5µsec/div)
Fig.6 Transient Response
(3→0A)
Co=47µF
VCC
Ven
VIN
Vo
VCC→VIN→Ven
Fig.9 Input sequence
VCC
Ven
VIN
Vo
VIN→VCC→Ven
Fig.10 Input sequence
VCC
Ven
VIN
Vo
Ven→VCC→VIN
Fig.11 Input sequence
www.rohm.com
© 2010 ROHM Co., Ltd. All rights reserved.
5/20
VCC
Ven
VIN
Vo
VCC→Ven→VIN
Fig.12 Input sequence
2010.04 - Rev.C
5 Page 
BD3508MUV,BD3509MUV
Technical Note
●Operation of Each Block
・AMP
This is an error amp that functions by comparing the reference voltage (0.65V) with Vo to drive the output Nch FET
(Ron=50mΩ). Frequency optimization helps to realize rapid transit response, and to support the use of functional polymer
output capacitors. AMP input voltage ranges from GND to 2.7V, while the AMP output ranges from GND to VCC. When EN
is OFF, or when UVLO is active, output goes LOW and the output NchFET switches OFF.
・EN
The EN block controls the regulator ON/OFF pin by means of the logic input pin. In OFF position, circuit voltage is
maintained at 0µA, thus minimizing current consumption at standby. The FET is switched ON to enable discharge of the
NRCS pin Vo, thereby draining the excess charge and preventing the load IC from malfunctioning. Since no electrical
connection is required (such as between the VCC pin and the ESD prevention Di), module operation is independent of the
input sequence.
・UVLO
To prevent malfunctions that can occur when there is a momentary decrease in VCC supply voltage, the UVLO circuit
switches output OFF, and, like the EN block, discharges the NRCS Vo. Once the UVLO threshold voltage (TYP3.80V) is
exceeded, the power-on reset is triggered and output begins.
・CURRENT LIMIT
With output ON, the current limit function monitors internal IC output current against the parameter value. When current
exceeds this level, the current limit module lowers the output current to protect the load IC. When the overcurrent state is
eliminated, output voltage is restored at the parameter value.
・NRCS
The soft start function is realized by connecting an NRCS pin external capacitor to the target ground. Output ramp-up can
be set for any period up to the time the NRCS pin reaches VFB (0.65V). During startup, the NRCS pin serves as the 20µA
(TYP) constant current source and charges the externally connected capacitor.
・TSD (Thermal Shut Down)
The shutdown (TSD) circuit automatically switches output OFF when the chip temperature gets too high, thus serving to
protect the IC against “thermal runaway” and heat damage. Because the TSD circuit is provided to shut down the IC in the
presence of extreme heat, in order to avoid potential problems with the TSD, it is crucial that the Tj (max) parameter not be
exceeded in the thermal design.
・VIN
The VIN line is the major current supply line, and is connected to the output NchFET drain. Since no electrical connection
(such as between the VCC pin and an ESD protective Di) is necessary, VIN operates independent of the input sequence.
However, since there is an output NchFET body Di between VIN and Vo, a VIN-Vo electric (Di) connection is present. Note,
therefore, that when output is switched ON or OFF, reverse current may flow to the VIN from Vo.
・PGOOD (BD3509MUV)
This is the monitor pin for output voltage (Vo). It is used through the pull-up resistance (100kΩ). PGOOD pin judges the
voltage High or Low (FB Voltage 0.585V typ. : threshold voltage).
www.rohm.com
© 2010 ROHM Co., Ltd. All rights reserved.
11/20
2010.04 - Rev.C
11 Page | ||
| Páginas | Total 23 Páginas | |
| PDF Descargar | [ Datasheet BD3509MUV.PDF ] | |
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