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參數(shù)資料
| 型號： | LX1676-CLQTR |
| 廠商： | MICROSEMI CORP-ANALOG MIXED SIGNAL GROUP |
| 元件分類： | 穩(wěn)壓器 |
| 英文描述： | 1.5 A SWITCHING CONTROLLER, 1100 kHz SWITCHING FREQ-MAX, PQCC38 |
| 封裝： | PLASTIC, MLPQ-38 |
| 文件頁數(shù)： | 16/16頁 |
| 文件大?。?/td> | 387K |
| 代理商： | LX1676-CLQTR |
LX1676
PRELIMINARY DATA SHEET
Microsemi
Integrated Products Division
11861 Western Avenue, Garden Grove, CA. 92841, 714-898-8121, Fax: 714-893-2570
Page 9
WWW
.Microse
m
i
.CO
M
Mobile AMD Athlon
VRM Controller
I N T E GR A T ED
PRODUCT S
Copyright
2000
Revision: 0.4b, 9/14/2004
TH EORY OF O PERAT ION
GENERAL DESCRIPTION
The LX1676 is a voltage-mode pulse-width modulation
controller integrated circuit.
The PWM frequency is
programmable from 200kHz to 1MHz. The device has
external compensation, for more flexibility of the loop
response. The LX1676 also makes use of a true differential
input amplifier for remote voltage sensing at the actual
processor core. This is a very important feature now that
the core voltages are in the 1 to 2 volt range. The reference
for the biphase PWM output is a 5 bit VID code DAC. The
VID code DAC can generate a reference voltage of 0.925 to
2.000 volts. The output of the DAC is a bi-directional
current source and is connected to the DACOUT pin.
Connecting a capacitor from this pin to ground will
generate a linear ramp, which will determine the rate of
change of the output voltage. The rate of change can be set
so that the current required to charge the total output
capacitance is below the maximum current limit trip point.
This will allow VID changes on the fly without tripping the
over current sensor.
POWER UP AND INITIALIZATION
At power up, the LX1676 monitors the supply voltage to
VCC and Vin, Before both supplies reach their under-
voltage lock-out (UVLO) thresholds, a power on reset
condition will prevent soft-start from beginning, the
oscillator is disabled and all MOSFETs are kept off.
SOFT-START
Once the supplies are above the UVLO threshold and the
Enable pin is brought high, the soft-start capacitor begins to
be charged up by the reference DAC through the DACOUT
pin. The capacitor voltage at the DACOUT pin rises as a
linear ramp. The DACOUT pin is connected to the error
amplifier’s non-inverting input which controls the output
voltage. The output voltage will follow the DACOUT pin
voltage.
Phase 3 (hysteretic phase) is disabled during soft-start.
OVER-CURRENT PROTECTION
There are two separate current limit circuits in the
LX1676. One looks at the phase 1 lower MOSFET drain
current and the second looks at the phase 3 upper MOSFET
drain current. Both circuits have a 400 nS delay before a
current limit command is issued to the current limit latch,
once set the current limit latch will hold all three phases off
until it is reset.
The Over-Current Protection is disabled during positive
VID changes.
To reset the current limit latch either the enable command
(ENA) must be cycled low then back high or the input
power must cycle off and then back on.
OVER-CURRENT PROTECTION (PHASE 1)
The phase 1 current limit uses the RDS(ON) of the
lower MOSFET, together with a resistor (RSET) to set the
actual current limit point. The current limit comparator
senses the current 400 nS after the lower MOSFET is
switched on. A current source supplies a current (ISET),
of 50A which flows into RSET and determines the
current limit trip point. The value of RSET is selected to
set the current limit for the application.
Phase 1 RSET is calculated by:
A
50
R
ILimit
R
DS(ON)
SET
=
The current limit comparator will trip when the drop
across RSET equals the drop across the lower MOSFET
RDS(ON)., at this time the comparator outputs a signal to
set the I limit latch and removes the enable command. The
Over-Current sensing is done on phase 1 only because
phase 2 current is always being forced to equal the phase
1 current, therefore the current trip point is set at half of the
desired current limit. For an output current limit setting of
30 amps, the current trip point for phase 1 is set at 15
amps.
When the phase 1 over current latch is set all three
phases are disabled, all MOSFETs are turned off.
Vout
50 uA
+
_
RSET
Q2
Current
Flow
+
_
Iout
Current Limit
Comparator
Q1
Vin
RDS(ON)
400nSec Delay
Figure 3 – Phase 1 Current Limit
The delay before current limit is activated will result in
current pulses exceeding the calculated values during the
delay period if a short circuit is applied during that time.
AA
PP
LL
IICC
AA
TT
IIOO
NN
SS
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相關(guān)代理商/技術(shù)參數(shù) |
參數(shù)描述 |
|---|---|
| LX1676CPW | 功能描述:IC CTRLR PS VRM BIPHASE 38TSSOP RoHS:是 類別:集成電路 (IC) >> PMIC - 穩(wěn)壓器 - 專用型 系列:- 標(biāo)準(zhǔn)包裝:2,000 系列:- 應(yīng)用:控制器，DSP 輸入電壓:4.5 V ~ 25 V 輸出數(shù):2 輸出電壓:最低可調(diào)至 1.2V 工作溫度:-40°C ~ 85°C 安裝類型:表面貼裝 封裝/外殼:30-TFSOP（0.173"，4.40mm 寬） 供應(yīng)商設(shè)備封裝:30-TSSOP 包裝:帶卷 (TR) |
| LX1676-CPW | 制造商:MICROSEMI 制造商全稱:Microsemi Corporation 功能描述:Mobile AMD AthlonTM VRM Controller |
| LX1677 | 制造商:MICROSEMI 制造商全稱:Microsemi Corporation 功能描述:AMD64 Processor VRM Controller |
| LX1677 EVAL KIT | 制造商:Microsemi Corporation 功能描述:PWM CONTROLLERS - Bulk |
| LX1677CLQ | 功能描述:IC CTRLR VRM PS 2PHASE 38MLPQ RoHS:是 類別:集成電路 (IC) >> PMIC - 穩(wěn)壓器 - 專用型 系列:- 產(chǎn)品培訓(xùn)模塊:Lead (SnPb) Finish for COTS Obsolescence Mitigation Program 標(biāo)準(zhǔn)包裝:2,000 系列:- 應(yīng)用:電源，ICERA E400，E450 輸入電壓:4.1 V ~ 5.5 V 輸出數(shù):10 輸出電壓:可編程 工作溫度:-40°C ~ 85°C 安裝類型:表面貼裝 封裝/外殼:42-WFBGA，WLCSP 供應(yīng)商設(shè)備封裝:42-WLP 包裝:帶卷 (TR) |
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