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參數(shù)資料
| 型號： | EL7585AILZ-T13 |
| 廠商： | INTERSIL CORP |
| 元件分類： | 穩(wěn)壓器 |
| 英文描述： | TFT-LCD Power Supply |
| 中文描述： | 3.5 A SWITCHING REGULATOR, 1100 kHz SWITCHING FREQ-MAX, QCC20 |
| 封裝： | 4 X 4 MM, ROHS COMPLIANT, MO-220, QFN-20 |
| 文件頁數(shù)： | 14/18頁 |
| 文件大?。?/td> | 730K |
| 代理商： | EL7585AILZ-T13 |
14
FN7523.2
September 21, 2005
there is a fault condition on C
DLY
or V
REF
. If a fault is
detected, the outputs and the input protection will turn off,
but V
REF
will stay on. If no fault is found, C
CDLY
continues
ramping up and down.
During the second ramp, the device checks the status of
V
REF
and over temperature. At the peak of the second ramp,
PG output goes low and enables the input protection PMOS
Q1. Q1 is a controlled FET used to prevent in-rush current into
V
BOOST
before V
BOOST
is enabled internally. Its rate of turn
on is controlled by C
o
. When a fault is detected, M1 will turn
off and disconnect the inductor from V
IN
.
With the input protection FET on, NODE1 (See Typical
Application Diagram) will rise to ~V
IN
. Initially the boost is not
enabled so V
BOOST
rises to V
IN
-V
DIODE
through the output
diode. Hence, there is a step at V
BOOST
during this part of the
start-up sequence. If this step is not desirable, an external
PMOS FET can be used to delay the output until the boost is
enabled internally. The delayed output appears at A
VDD
.
For EL7585A, V
BOOST
soft-start at the beginning of the third
ramp. The soft-start ramp depends on the value of the C
DLY
capacitor. For C
DLY
of 220nF, the soft-start time is ~2ms.
V
OFF
turns on at the start of the fourth peak. At the fifth
peak, DELB gate goes low to turn on the external PMOS Q4
to generate a delayed V
BOOST
output.
V
ON
is enabled at the beginning of the sixth ramp. A
VDD
,
PG, V
OFF
, DELB and V
ON
are checked at end of this ramp.
Fault Protection
During the startup sequence, prior to BOOST soft-start,
V
REF
is checked to be within ±20% of its final value and the
device temperature is checked. If either of these are not
within the expected range, the part is disabled until the
power is recycled or EN is toggled.
If C
DELAY
is shorted low, then the sequence will not start,
while if C
DELAY
is shorted H, the first down ramp will not
occur and the sequence will not complete.
Once the start-up sequence is completed, the chip
continuously monitors C
DLY
, DELB, FBP, FBL, FBN, V
REF
,
FBB and PG and checks for faults. During this time, the
voltage on the C
DLY
capacitor remains at 1.15V until either a
fault is detected, or the EN pin is pulled low.
A fault on C
DELAY
, V
REF
or temperature will shut down the
chip immediately. If a fault on any other output is detected,
C
DELAY
will ramp up linearly with a 5μA (typical) current to
the upper fault threshold (typically 2.4V), at which point the
chip is disabled until the power is recycled or EN is toggled.
If the fault condition is removed prior to the end of the ramp,
the voltage on the C
DLY
capacitor returns to 1.15V.
Typical fault thresholds for FBP, FBL, FBN and FBB are
included in the tables. PG and DELB fault thresholds are
typically 0.6V.
C
INT
has an internal current-limited clamp to keep the
voltage within its normal range. If C
INT
is shorted low, the
boost regulator will attempt to regulate to 0V. If C
INT
is
shorted H, the regulator switches to P mode.
If any of the regulated outputs (V
BOOST
, V
ON
, V
OFF
or
V
LOGIC
) are driven above their target levels the drive
circuitry will switch off until the output returns to its expected
value.
If V
BOOST
is excessively loaded, the current limit will
prevent damage to the chip. While in current limit, the part
acts like a current source and the regulated output will drop.
If the output drops below the fault threshold, a ramp will be
initiated on C
DELAY
and, provided that the fault is sustained,
the chip will be disabled on completion of the ramp.
In some circumstances, (depending on ambient temperature
and thermal design of the board), continuous operation at
current limit may result in the over-temperature threshold
being exceeded, which will cause the part to disable
immediately.
All I/O also have ESD protection, which in many cases will
also provide overvoltage protection, relative to either ground
or V
DD
. However, these will not generally operate unless
abs max ratings are exceeded.
Component Selection for Start-Up Sequencing and
Fault Protection
The C
REF
capacitor is typically set at 220nF and is required
to stabilize the V
REF
output. The range of C
REF
is from
22nF to 1μF and should not be more than five times the
capacitor on C
DEL
to ensure correct start-up operation.
The C
DEL
capacitor is typically 220nF and has a usable
range from 47nF minimum to several microfarads - only
limited by the leakage in the capacitor reaching μA levels.
C
DEL
should be at least 1/5 of the value of C
REF
(See
above). Note with 220nF on C
DEL
the fault time-out will be
typically 50ms and the use of a larger/smaller value will vary
this time proportionally (e.g. 1μF will give a fault time-out
period of typically 230ms).
Fault Sequencing
The EL7585A has an advanced fault detection system which
protects the IC from both adjacent pin shorts during
operation and shorts on the output supplies.
A high quality layout/design of the PCB, in respect of
grounding quality and decoupling is necessary to avoid
falsely triggering the fault detection scheme - especially
during start-up. The user is directed to the layout guidelines
and component selection sections to avoid problems during
initial evaluation and prototype PCB generation.
EL7585A
相關PDF資料 |
PDF描述 |
|---|---|
| EL7585AILZ-T7 | TFT-LCD Power Supply |
| EL7585IL-T13 | TFT-LCD Power Supply |
| EL7585IL-T7 | TFT-LCD Power Supply |
| EL7585 | TFT-LCD Power Supply |
| EL7585IL | TFT-LCD Power Supply |
相關代理商/技術參數(shù) |
參數(shù)描述 |
|---|---|
| EL7585AILZ-T7 | 功能描述:IC POWER SUPPLY TFT-LCD 20-QFN RoHS:是 類別:集成電路 (IC) >> PMIC - 穩(wěn)壓器 - 專用型 系列:- 產(chǎn)品培訓模塊:Lead (SnPb) Finish for COTS Obsolescence Mitigation Program 標準包裝:2,000 系列:- 應用: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 供應商設備封裝:42-WLP 包裝:帶卷 (TR) |
| EL7585AP_06 | 制造商:INTERSIL 制造商全稱:Intersil Corporation 功能描述:TFT-LCD Power Supply |
| EL7585IL | 制造商:INTERSIL 制造商全稱:Intersil Corporation 功能描述:TFT-LCD Power Supply |
| EL7585IL-T13 | 制造商:INTERSIL 制造商全稱:Intersil Corporation 功能描述:TFT-LCD Power Supply |
| EL7585IL-T7 | 制造商:INTERSIL 制造商全稱:Intersil Corporation 功能描述:TFT-LCD Power Supply |
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