- 您现在的位置：买卖IC网 > PDF目录377712 > LT1683IG (LINEAR TECHNOLOGY CORP) Ultralow Noise Push-Pull DC/DC Controller PDF资料下载
参数资料
| 型号： | LT1683IG |
| 厂商： | LINEAR TECHNOLOGY CORP |
| 元件分类： | 稳压器 |
| 英文描述： | Ultralow Noise Push-Pull DC/DC Controller |
| 中文描述： | SWITCHING CONTROLLER, 250 kHz SWITCHING FREQ-MAX, PDSO20 |
| 封装： | 5.30 MM, PLASTIC, SSOP-20 |
| 文件页数： | 15/24页 |
| 文件大小： | 237K |
| 代理商： | LT1683IG |
15
LT1683
1683f
LT1683 will act to prevent either output from going
beyond its set output voltage. The highest output (lightest
load) will dominate control of the regulator. This technique
would prevent either output from going unregulated high
at no load. However, this technique will also compromise
output load regulation.
Shutdown
If SHDN is pulled low, the regulator will turn off. As the
SHDN pin voltage is increased from ground the internal
bandgap regulator will be powered on. This will set a 1.39V
threshold for turn on of the internal regulator that runs
most of the control circuitry of the regulator. Note after the
control circuitry powers on, gate driver activity will depend
on the voltage of V
IN
with respect to the voltage on GCL.
As the SHDN pin enables the internal regulator a 24
μ
A
current will be sourced from the pin that can provide
hysteresis for undervoltage lockout. This hysteresis can
be used to prevent part shutdown due to input voltage sag
from an initial high current draw.
In addition to the current hysteresis, there is also approxi-
mately 100mV of voltage hysteresis on the SHDN pin.
When the SHDN pin is greater than 2.2V, the hysteretic
current from the part will be reduced to essentially zero.
If a resistor divider is used to set the turn on threshold then
the resistors are determined by the following equations.
V
RA
RB
RB
V
V
RA
V
RA RB
I
ON
SHDN
HYST
SHDN
SHDN
=
+
=
+
Reworking these equations yields:
RA
V
(
V
I
V
V
V
V
RB
V
(
V
V
I
V
V
HYST
SHDN
ON
SHDN
SHDN
SHDN
HYST
SHDN
(
ON
SHDN
SHDN
ON
SHDN
=
=
)
(
)
)
)
APPLICATIU
The FB bias current represents a small error and can
usually be ignored for values of R1||R2 up to 10k.
One word of caution, sometimes a feedback zero is added
to the control loop by placing a capacitor across R1. If the
feedback capacitively pulls the FB pin above the internal
regulator voltage (2.4V), output regulation may be dis-
rupted. A series resistance with the feedback pin can
eliminate this potential problem. There is an internal clamp
on FB that clamps at 0.7V above the regulation voltage that
should also help prevent this problem.
W
U
U
FB PIN
1683 F03
V
OUT
R2
R1
NFB PIN
I
NFB
1683 F04
–V
OUT
R2
R1
Figure 3
Figure 4
Negative Output Voltage Setting
Negative output voltage can be sensed using the NFB pin.
In this case regulation will occur when the NFB pin is at
–2.5V. The nominal input bias current for the NFB is –25
μ
A
(I
NFB
), which needs to be accounted for in setting up the
divider.
Referring to Figure 4, R1 is chosen such that:
R
R
V
R
A
OUT
+
1
2
2 5
.
2 5
.
2 25
=
μ
A suggested value for R2 is 2.5k. The NFB pin is normally
left open if the FB pin is being used.
V
IN
RA
RB
SHDN
Dual Polarity Output Voltage Sensing
Certain applications may benefit from sensing both posi-
tive and negative output voltages. When doing this each
output voltage resistor divider is individually set as previ-
ously described. When both FB and NFB pins are used, the
相关PDF资料 |
PDF描述 |
|---|---|
| LT1683 | Ultralow Noise Push-Pull DC/DC Controller |
| LT1683EG | Ultralow Noise Push-Pull DC/DC Controller |
| LT1719CS6 | 4.5ns Single/Dual Supply 3V/5V Comparator with Rail-to-Rail Output |
| LT1719IS6 | 4.5ns Single/Dual Supply 3V/5V Comparator with Rail-to-Rail Output |
| LT1721CS | Dual/Quad, 4.5ns, Single Supply 3V/5V Comparators with Rail-to-Rail Outputs |
相关代理商/技术参数 |
参数描述 |
|---|---|
| LT1683IG#PBF | 功能描述:IC REG CTRLR PWM CM 20-SSOP RoHS:是 类别:集成电路 (IC) >> PMIC - 稳压器 - DC DC 切换控制器 系列:- 标准包装:4,500 系列:PowerWise® PWM 型:控制器 输出数:1 频率 - 最大:1MHz 占空比:95% 电源电压:2.8 V ~ 5.5 V 降压:是 升压:无 回扫:无 反相:无 倍增器:无 除法器:无 Cuk:无 隔离:无 工作温度:-40°C ~ 125°C 封装/外壳:6-WDFN 裸露焊盘 包装:带卷 (TR) 配用:LM1771EVAL-ND - BOARD EVALUATION LM1771 其它名称:LM1771SSDX |
| LT1683IG#TR | 功能描述:IC REG CTRLR PWM CM 20-SSOP RoHS:否 类别:集成电路 (IC) >> PMIC - 稳压器 - DC DC 切换控制器 系列:- 标准包装:4,500 系列:PowerWise® PWM 型:控制器 输出数:1 频率 - 最大:1MHz 占空比:95% 电源电压:2.8 V ~ 5.5 V 降压:是 升压:无 回扫:无 反相:无 倍增器:无 除法器:无 Cuk:无 隔离:无 工作温度:-40°C ~ 125°C 封装/外壳:6-WDFN 裸露焊盘 包装:带卷 (TR) 配用:LM1771EVAL-ND - BOARD EVALUATION LM1771 其它名称:LM1771SSDX |
| LT1683IG#TRPBF | 功能描述:IC REG CTRLR PWM CM 20-SSOP RoHS:是 类别:集成电路 (IC) >> PMIC - 稳压器 - DC DC 切换控制器 系列:- 标准包装:4,500 系列:PowerWise® PWM 型:控制器 输出数:1 频率 - 最大:1MHz 占空比:95% 电源电压:2.8 V ~ 5.5 V 降压:是 升压:无 回扫:无 反相:无 倍增器:无 除法器:无 Cuk:无 隔离:无 工作温度:-40°C ~ 125°C 封装/外壳:6-WDFN 裸露焊盘 包装:带卷 (TR) 配用:LM1771EVAL-ND - BOARD EVALUATION LM1771 其它名称:LM1771SSDX |
| LT1684 | 制造商:LINER 制造商全称:Linear Technology 功能描述:Micropower Ring Tone Generator |
| LT1684CN | 功能描述:IC RING TONE GENERATOR 14-DIP RoHS:否 类别:集成电路 (IC) >> 接口 - 电信 系列:- 产品培训模块:Lead (SnPb) Finish for COTS 产品变化通告:Product Discontinuation 06/Feb/2012 标准包装:750 系列:* |
发布紧急采购，3分钟左右您将得到回复。