- 您现在的位置：买卖IC网 > PDF目录15266 > LTC1702IGN (Linear Technology)IC REG CTRLR BUCK PWM VM 24-SSOP PDF资料下载
参数资料
| 型号： | LTC1702IGN |
| 厂商： | Linear Technology |
| 文件页数： | 28/36页 |
| 文件大小： | 0K |
| 描述： | IC REG CTRLR BUCK PWM VM 24-SSOP |
| 标准包装： | 55 |
| 系列： | PolyPhase® |
| PWM 型： | 电压模式 |
| 输出数： | 2 |
| 频率 - 最大： | 750kHz |
| 占空比： | 93% |
| 电源电压： | 3 V ~ 7 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 ~ 85°C |
| 封装/外壳： | 24-SSOP（0.154"，3.90mm 宽） |
| 包装： | 管件 |
第1页第2页第3页第4页第5页第6页第7页第8页第9页第10页第11页第12页第13页第14页第15页第16页第17页第18页第19页第20页第21页第22页第23页第24页第25页第26页第27页当前第28页第29页第30页第31页第32页第33页第34页第35页第36页
LTC1702
APPLICATIO N S I N FOR M ATIO N
Maximizing Low Load Current Efficiency
Low load current efficiency depends strongly on proper
operation in discontinuous and Burst Mode operations. In
an ideally optimized system, discontinuous mode reduces
conduction losses but not switching losses, since each
power MOSFET still switches on and off once per cycle. In
a typical system, there is additional loss in discontinuous
mode due to a small amount of residual current left in the
inductor when QB turns off. This current gets dissipated
across the body diode of either QT or QB. Some LTC1702
systems lose as much to body diode conduction as they
save in MOSFET conduction. The real efficiency benefit of
discontinuous mode happens when Burst Mode operation
is invoked. At typical power levels, when Burst Mode
operation is activated, gate drive is the dominant loss
term. Burst Mode operation turns off all output switching
for several clock cycles in a row, significantly cutting gate
drive losses. As the load current in Burst Mode operation
falls toward zero, the current drawn by the circuit falls to
the LTC1702’s background quiescent level—about 3mA
per channel.
To maximize low load efficiency, make sure the LTC1702
is allowed to enter discontinuous and Burst Mode opera-
tion as cleanly as possible. FCB must be above its 0.8V
threshold. Minimize ringing at the SW node so that the
discontinuous comparator leaves as little residual current
in the inductor as possible when QB turns off. It helps to
connect the SW pin of the LTC1702 as close to the drain
of QB as possible. An RC snubber network can also be
added from SW to PGND.
REGULATION OVER COMPONENT TOLERANCE/
TEMPERATURE
DC Regulation Accuracy
The LTC1702 initial DC output accuracy depends mainly
on internal reference accuracy, op amp offset and external
resistor accuracy. Two LTC1702 specs come into play:
feedback voltage and feedback voltage line regulation. The
feedback voltage spec is 800mV ± 8mV over the full
temperature range, and is specified at the FB pin, which
encompasses both reference accuracy and any op amp
offset.Thisaccountsfor1%errorattheoutputwitha5V
input supply. The feedback voltage line regulation spec
adds an additional 0.05%/V term that accounts for change
in reference output with change in input supply voltage.
With a 5V supply, the errors contributed by the LTC1702
itself add up to no more than 1% DC error at the output.
The output voltage setting resistors (R1 and R B in
Figure 3) are the other major contributor to DC error. At a
typical 1.xV output voltage, the resistors are of roughly the
same value, which tends to halve their error terms, im-
proving accuracy. Still, using 1% resistors for R1 and R B
will add 1% to the total output error budget, equal to that
of all errors due to the LTC1702 combined. Using 0.1%
resistors in just those two positions can nearly halve the
DC output error for very little additional cost.
Load Regulation
Load regulation is affected by feedback voltage, feedback
amplifier gain and external ground drops in the feedback
path. Feedback voltage is covered above and is within 1%
over temperature. A full-range load step might require a
10% duty cycle change to keep the output constant,
requiring the COMP pin to move about 100mV. With
amplifier gain at 85dB, this adds up to only a 10 μ V shift at
FB, negligible compared to the reference accuracy terms.
External ground drops aren’t so negligible. The LTC1702
can sense the positive end of the output voltage by
attaching the feedback resistor directly at the load, but it
cannot do the same with the ground lead. Just 0.001 ? of
resistance in the ground lead at 10A load will cause a 10mV
error in the output voltage —as much as all the other DC
errors put together. Proper layout becomes essential to
achieving optimum load regulation from the LTC1702.
See the Layout/Troubleshooting section for more infor-
mation. A properly laid out LTC1702 circuit should move
less than a millivolt at the output from zero to full load.
TRANSIENT RESPONSE
Transient response is the other half of the regulation
equation. The LTC1702 can keep the DC output voltage
constant to within 1% when averaged over hundreds of
1702fa
28
相关PDF资料 |
PDF描述 |
|---|---|
| RSC18DRTS | CONN EDGECARD 36POS DIP .100 SLD |
| H2AAT-10103-R4-ND | JUMPER-H1502TR/A2015R/H1502TR 3" |
| VE-25Z-EU-F1 | CONVERTER MOD DC/DC 2V 80W |
| SLP682M025C1P3 | CAP ALUM 6800UF 25V 20% SNAP |
| H2AAT-10103-N4-ND | JUMPER-H1502TR/A2015N/H1502TR 3" |
相关代理商/技术参数 |
参数描述 |
|---|---|
| LTC1702IGN#PBF | 功能描述:IC REG CTRLR BUCK PWM VM 24-SSOP RoHS:是 类别:集成电路 (IC) >> PMIC - 稳压器 - DC DC 切换控制器 系列:PolyPhase® 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 |
| LTC1702IGN#TR | 功能描述:IC REG CTRLR BUCK PWM VM 24-SSOP RoHS:否 类别:集成电路 (IC) >> PMIC - 稳压器 - DC DC 切换控制器 系列:PolyPhase® 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 |
| LTC1702IGN#TRPBF | 功能描述:IC REG CTRLR BUCK PWM VM 24-SSOP RoHS:是 类别:集成电路 (IC) >> PMIC - 稳压器 - DC DC 切换控制器 系列:PolyPhase® 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 |
| LTC1703CG | 功能描述:IC REG SW DUAL SYNC VID 28SSOP RoHS:否 类别:集成电路 (IC) >> PMIC - 稳压器 - 专用型 系列:- 标准包装:43 系列:- 应用:控制器，Intel VR11 输入电压:5 V ~ 12 V 输出数:1 输出电压:0.5 V ~ 1.6 V 工作温度:-40°C ~ 85°C 安装类型:表面贴装 封装/外壳:48-VFQFN 裸露焊盘 供应商设备封装:48-QFN（7x7） 包装:管件 |
| LTC1703CG#PBF | 功能描述:IC REG SW DUAL SYNC VID 28SSOP RoHS:是 类别:集成电路 (IC) >> PMIC - 稳压器 - 专用型 系列:- 标准包装:2,000 系列:- 应用:控制器，DSP 输入电压:4.5 V ~ 25 V 输出数:2 输出电压:最低可调至 1.2V 工作温度:-40°C ~ 85°C 安装类型:表面贴装 封装/外壳:30-TFSOP（0.173"，4.40mm 宽） 供应商设备封装:30-TSSOP 包装:带卷 (TR) |
发布紧急采购，3分钟左右您将得到回复。