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參數(shù)資料
| 型號(hào)： | LTC1929IG |
| 廠商： | LINEAR TECHNOLOGY CORP |
| 元件分類： | 穩(wěn)壓器 |
| 英文描述： | Isolated Flyback Switching Regulator with 9V Output |
| 中文描述： | 3 A DUAL SWITCHING CONTROLLER, 310 kHz SWITCHING FREQ-MAX, PDSO28 |
| 封裝： | 0.209 INCH, PLASTIC, SSOP-28 |
| 文件頁數(shù)： | 14/24頁 |
| 文件大?。?/td> | 233K |
| 代理商： | LTC1929IG |
14
LTC1929
This built-in overcurrent latchoff can be overridden by
providing a pull-up resistor, R
SS
, to the RUN/SS pin as
shown in Figure 6. This resistance shortens the soft-start
period and prevents the discharge of the RUN/SS capaci-
tor during a severe overcurrent and/or short-circuit con-
dition. When deriving the 5
μ
A current from V
IN
as in the
figure, current latchoff is always defeated. The diode
connecting of this pull-up resistor to INTV
CC
, as in
Figure6, eliminates any extra supply current during shut-
down while eliminating the INTV
CC
loading from prevent-
ing controller start-up.
Why should you defeat current latchoff During the
prototyping stage of a design, there may be a problem with
noise pickup or poor layout causing the protection circuit
to latch off the controller. Defeating this feature allows
troubleshooting of the circuit and PC layout. The internal
short-circuit and foldback current limiting still remains
active, thereby protecting the power supply system from
failure. A decision can be made after the design is com-
plete whether to rely solely on foldback current limiting or
to enable the latchoff feature by removing the pull-up
resistor.
The value of the soft-start capacitor C
SS
may need to be
scaled with output voltage, output capacitance and load
current characteristics. The minimum soft-start capaci-
tance is given by:
C
SS
> (C
OUT
)(V
OUT
)(10
-4
)(R
SENSE
)
The minimum recommended soft-start capacitor of C
SS
=
0.1
μ
F will be sufficient for most applications.
APPLICATIU
W
U
U
Figure 6. RUN/SS Pin Interfacing
Phase-Locked Loop and Frequency Synchronization
The LTC1929 has a phase-locked loop comprised of an
internal voltage controlled oscillator and phase detector.
This allows the top MOSFET turn-on to be locked to the
rising edge of an external source. The frequency range of
the voltage controlled oscillator is
±
50% around the
center frequency f
O
. A voltage applied to the PLLFLTR pin
of 1.2V corresponds to a frequency of approximately
220kHz. The nominal operating frequency range of the
LTC1929 is 140kHz to 310kHz.
The phase detector used is an edge sensitive digital type
which provides zero degrees phase shift between the
external and internal oscillators. This type of phase detec-
tor will not lock up on input frequencies close to the
harmonics of the VCO center frequency. The PLL hold-in
range,
f
H
, is equal to the capture range,
f
C:
f
H
=
f
C
=
±
0.5 f
O
(150kHz-300kHz)
The output of the phase detector is a complementary pair
of current sources charging or discharging the external
filter network on the PLLFLTR pin. A simplified block
diagram is shown in Figure 7.
If the external frequency (f
PLLIN
) is greater than the oscil-
lator frequency f
0SC
, current is sourced continuously,
pulling up the PLLFLTR pin. When the external frequency
is less than f
0SC
, current is sunk continuously, pulling
down the PLLFLTR pin. If the external and internal fre-
quencies are the same but exhibit a phase difference, the
current sources turn on for an amount of time correspond-
ing to the phase difference. Thus the voltage on the
PLLFLTR pin is adjusted until the phase and frequency of
the external and internal oscillators are identical. At this
stable operating point the phase comparator output is
open and the filter capacitor C
LP
holds the voltage. The
LTC1929 PLLIN pin must be driven from a low impedance
source such as a logic gate located close to the pin.
The loop filter components (C
LP
, R
LP
) smooth out the
current pulses from the phase detector and provide a
stable input to the voltage controlled oscillator. The filter
components C
LP
and R
LP
determine how fast the loop
acquires lock. Typically R
LP
=10k
and C
LP
is 0.01
μ
F to
0.1
μ
F.
3.3V OR 5V
RUN/SS
V
IN
INTV
CC
RUN/SS
D1
D1*
C
SS
R
SS
*
C
SS
R
SS
*
1929 F06
*OPTIONAL TO DEFEAT OVERCURRENT LATCHOFF
相關(guān)PDF資料 |
PDF描述 |
|---|---|
| LTC1929C | Isolated Flyback Switching Regulator with 9V Output |
| LTC1929CG | Isolated Flyback Switching Regulator with 9V Output |
| LTC1929I | Isolated Flyback Switching Regulator with 9V Output |
| LTC1929 | 500kHz and 1MHz High Efficiency 1.5A Switching Regulators; Package: SO; No of Pins: 8; Temperature Range: -40?°C to 85?°C |
| LTC1929-PG | 500kHz and 1MHz High Efficiency 1.5A Switching Regulators; Package: SO; No of Pins: 8; Temperature Range: -40?°C to 85?°C |
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| LTC1929IG#PBF | 功能描述:IC REG CTRLR BUCK PWM CM 28-SSOP RoHS:是 類別:集成電路 (IC) >> PMIC - 穩(wěn)壓器 - DC DC 切換控制器 系列:- 標(biāo)準(zhǔn)包裝:4,500 系列:PowerWise® PWM 型:控制器 輸出數(shù):1 頻率 - 最大:1MHz 占空比:95% 電源電壓:2.8 V ~ 5.5 V 降壓:是 升壓:無 回掃:無 反相:無 倍增器:無 除法器:無 Cuk:無 隔離:無 工作溫度:-40°C ~ 125°C 封裝/外殼:6-WDFN 裸露焊盤 包裝:帶卷 (TR) 配用:LM1771EVAL-ND - BOARD EVALUATION LM1771 其它名稱:LM1771SSDX |
| LTC1929IG#TR | 功能描述:IC REG CTRLR BUCK PWM CM 28-SSOP RoHS:否 類別:集成電路 (IC) >> PMIC - 穩(wěn)壓器 - DC DC 切換控制器 系列:- 標(biāo)準(zhǔn)包裝:4,500 系列:PowerWise® PWM 型:控制器 輸出數(shù):1 頻率 - 最大:1MHz 占空比:95% 電源電壓:2.8 V ~ 5.5 V 降壓:是 升壓:無 回掃:無 反相:無 倍增器:無 除法器:無 Cuk:無 隔離:無 工作溫度:-40°C ~ 125°C 封裝/外殼:6-WDFN 裸露焊盤 包裝:帶卷 (TR) 配用:LM1771EVAL-ND - BOARD EVALUATION LM1771 其它名稱:LM1771SSDX |
| LTC1929IG#TRPBF | 功能描述:IC REG CTRLR BUCK PWM CM 28-SSOP RoHS:是 類別:集成電路 (IC) >> PMIC - 穩(wěn)壓器 - DC DC 切換控制器 系列:- 標(biāo)準(zhǔn)包裝:4,500 系列:PowerWise® PWM 型:控制器 輸出數(shù):1 頻率 - 最大:1MHz 占空比:95% 電源電壓:2.8 V ~ 5.5 V 降壓:是 升壓:無 回掃:無 反相:無 倍增器:無 除法器:無 Cuk:無 隔離:無 工作溫度:-40°C ~ 125°C 封裝/外殼:6-WDFN 裸露焊盤 包裝:帶卷 (TR) 配用:LM1771EVAL-ND - BOARD EVALUATION LM1771 其它名稱:LM1771SSDX |
| LTC1929IG-PG | 功能描述:IC REG CTRLR BUCK PWM CM 28-SSOP RoHS:否 類別:集成電路 (IC) >> PMIC - 穩(wěn)壓器 - DC DC 切換控制器 系列:- 標(biāo)準(zhǔn)包裝:4,500 系列:PowerWise® PWM 型:控制器 輸出數(shù):1 頻率 - 最大:1MHz 占空比:95% 電源電壓:2.8 V ~ 5.5 V 降壓:是 升壓:無 回掃:無 反相:無 倍增器:無 除法器:無 Cuk:無 隔離:無 工作溫度:-40°C ~ 125°C 封裝/外殼:6-WDFN 裸露焊盤 包裝:帶卷 (TR) 配用:LM1771EVAL-ND - BOARD EVALUATION LM1771 其它名稱:LM1771SSDX |
| LTC1929IG-PG#PBF | 功能描述:IC REG CTRLR BUCK PWM CM 28-SSOP RoHS:是 類別:集成電路 (IC) >> PMIC - 穩(wěn)壓器 - DC DC 切換控制器 系列:- 標(biāo)準(zhǔn)包裝:4,500 系列:PowerWise® PWM 型:控制器 輸出數(shù):1 頻率 - 最大:1MHz 占空比:95% 電源電壓:2.8 V ~ 5.5 V 降壓:是 升壓:無 回掃:無 反相:無 倍增器:無 除法器:無 Cuk:無 隔離:無 工作溫度:-40°C ~ 125°C 封裝/外殼:6-WDFN 裸露焊盤 包裝:帶卷 (TR) 配用:LM1771EVAL-ND - BOARD EVALUATION LM1771 其它名稱:LM1771SSDX |
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