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參數(shù)資料
| 型號： | LTC3722-1 |
| 廠商： | Linear Technology Corporation |
| 英文描述： | Synchronous Dual Mode Phase Modulated Full Bridge Controllers |
| 中文描述： | 同步相位調(diào)制的雙模式全橋控制器 |
| 文件頁數(shù)： | 16/28頁 |
| 文件大?。?/td> | 319K |
| 代理商： | LTC3722-1 |
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LTC3722-1/LTC3722-2
16
372212i
Programming Undervoltage Lockout
The LTC3722-1/LTC3722-2 provides undervoltage lock-
out (UVLO) control for the input DC voltage feed to the
power converter in addition to the V
CC
UVLO function
described in the preceding section. Input DC feed UVLO is
provided with the UVLO pin. A comparator on UVLO
compares a divided down input DC feed voltage to the 5V
precision reference. When the 5V level is exceeded on
UVLO, the SS pin is released and output switching com-
mences. At the same time a 10
μ
A current is enabled which
flows out of UVLO into the voltage divider connected to
UVLO. The amount of DC feed hysteresis provided by this
current is: 10
μ
A R
TOP
, see Figure 6. The system UVLO
threshold is: 5V {(R
TOP
+ R
BOTTOM
)/R
BOTTOM
}. If the
voltage applied to UVLO is present and greater than 5V
prior to the V
CC
UVLO circuitry activation, then the internal
UVLO logic will prevent output switching until the follow-
ing three conditions are met: (1) V
CC
UVLO is enabled, (2)
V
REF
is in regulation and (3) UVLO pin is greater than 5V.
UVLO can also be used to enable and disable the power
converter. An open drain transistor connected to UVLO as
shown in Figure 6 provides this capability.
maintains decent regulation as the supply voltage varies,
and it does not require full safety isolation from the input
winding of the transformer. Some manufacturers include
a primary winding for this purpose in their standard
product offerings as well. A different approach is to add a
winding to the output inductor and peak detect and filter
the square wave signal (see Figure 7b). The polarity of this
winding is designed so that the positive voltage square
wave is produced while the output inductor is freewheel-
ing. An advantage of this technique over the previous is
that it does not require a separate filter inductor and since
the voltage is derived from the well-regulated output
voltage, it is also well controlled. One disadvantage is that
this winding will require the same safety isolation that is
required for the main transformer. Another disadvantage
is that a much larger V
CC
filter capacitor is needed, since
it does not generate a voltage as the output is first starting
up, or during short-circuit conditions.
Figure 6. System UVLO Setup
ON OFF
R
BOTTOM
R
TOP
UVLO
3722 F0A
Figure 7a. Auxiliary Winding Bias Supply
1922 F05a
+
V
CC
V
IN
C
HOLD
0.1
μ
F
R
START
2k
15V*
*OPTIONAL
1922 F05b
V
CC
V
OUT
V
IN
C
HOLD
R
START
+
0.1
μ
F
L
OUT
ISO BARRIER
Figure 7b. Output Inductor Bias Supply
Off-Line Bias Supply Generation
If a regulated bias supply is not available to provide V
CC
voltage to the LTC3722-1/LTC3722-2 and supporting
circuitry, one must be generated. Since the power require-
ment is small, approximately 1W, and the regulation is not
critical, a simple open-loop method is usually the easiest
and lowest cost approach. One method that works well is
to add a winding to the main power transformer, and post
regulate the resultant square wave with an L-C filter (see
Figure7a). The advantage of this approach is that it
OPERATIOU
Programming the LTC3722-1/LTC3722-2 Oscillator
The high accuracy LTC3722-1/LTC3722-2 oscillator cir-
cuit provides flexibility to program the switching fre-
quency, slope compensation, and synchronization with
minimal external components. The LTC3722-1/LTC3722-2
相關(guān)PDF資料 |
PDF描述 |
|---|---|
| LTC3722EGN-1 | Synchronous Dual Mode Phase Modulated Full Bridge Controllers |
| LTC3722EGN-2 | Synchronous Dual Mode Phase Modulated Full Bridge Controllers |
| LTC1922-1 | Synchronous Dual Mode Phase Modulated Full Bridge Controllers |
| LTC1696 | Synchronous Dual Mode Phase Modulated Full Bridge Controllers |
| LTC3722-2 | Synchronous Dual Mode Phase Modulated Full Bridge Controllers |
相關(guān)代理商/技術(shù)參數(shù) |
參數(shù)描述 |
|---|---|
| LTC3722EGN-1 | 功能描述:IC REG CTRLR DIV ISO PWM 24SSOP 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 |
| LTC3722EGN-1#PBF | 功能描述:IC REG CTRLR DIV ISO PWM 24SSOP 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:2,000 系列:- PWM 型:電流模式 輸出數(shù):1 頻率 - 最大:1MHz 占空比:50% 電源電壓:9 V ~ 10 V 降壓:無 升壓:是 回掃:是 反相:無 倍增器:無 除法器:無 Cuk:無 隔離:無 工作溫度:-40°C ~ 85°C 封裝/外殼:8-TSSOP（0.173"，4.40mm 寬） 包裝:帶卷 (TR) |
| LTC3722EGN-1#TR | 功能描述:IC REG CTRLR DIV ISO PWM 24SSOP 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 |
| LTC3722EGN-1#TRPBF | 功能描述:IC REG CTRLR DIV ISO PWM 24SSOP 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 |
| LTC3722EGN-2 | 功能描述:IC REG CTRLR DIV ISO PWM 24SSOP 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 |
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