参数资料
| 型号： | LTC3831EGN |
| 厂商： | Linear Technology |
| 文件页数： | 8/20页 |
| 文件大小： | 0K |
| 描述： | IC SW REG CONTROLLR SYNC 16-SSOP |
| 标准包装： | 100 |
| 应用： | 控制器，DDR |
| 输入电压： | 3 V ~ 8 V |
| 输出数： | 1 |
| 输出电压： | 1.27 V ~ 4 V |
| 工作温度： | -40°C ~ 85°C |
| 安装类型： | 表面贴装 |
| 封装/外壳： | 16-SSOP（0.154"，3.90mm 宽） |
| 供应商设备封装： | 16-SSOP |
| 包装： | 管件 |
| 产品目录页面： | 1336 (CN2011-ZH PDF) |
LTC3831
TEST CIRCUITS
PV CC
V SHDN V CC
+
10 μ F
0.1 μ F
SHDN
V CC
PV CC2 PV CC1
I FB
NC
SS
TG
TG RISE/FALL
NC
V FB
FREQSET
FB
LTC3831
6800pF
V COMP
2.5V
COMP
R +
BG
BG RISE/FALL
R –
I MAX
GND
PGND
6800pF
3831 F02
Figure 2
APPLICATIONS INFORMATION
OVERVIEW
The LTC3831 is a voltage mode feedback, synchronous
switching regulator controller (see Block Diagram) de-
signed for use in high to medium power, DDR memory
termination. It includes an onboard PWM generator, a
ratiometric reference, two high power MOSFET gate
drivers and all necessary feedback and control circuitry
to form a complete switching regulator circuit. The PWM
loop nominally runs at 200kHz.
The LTC3831 is designed to generate an output voltage
that tracks at 1/2 of the external voltage connected be-
tween the R + and R – pins. The LTC3831 can be used to
generate the termination voltage, V TT , for interface like
the SSTL_2 where V TT is a ratio of the interface supply
voltage, V DDQ . It is a requirement in the SSTL_2 interface
standard for V TT to track the interface supply voltage to
improve noise immunity. Using the LTC3831 to supply the
interface termination voltage allows large current sourc-
ing and sinking through the termination resistors during
bus transitions.
The LTC3831 includes a current limit sensing circuit that
uses the topside external N-channel power MOSFET as
a current sensing element, eliminating the need for an
external sense resistor. Also included is an internal soft-
start feature that requires only a single external capacitor
to operate. In addition, the part features an adjustable
oscillator which can free run or synchronize to an external
signal with frequencies from 100kHz to 500kHz, allowing
added ?exibility in external component selection.
THEORY OF OPERATION
Primary Feedback Loop
The LTC3831 senses the output voltage of the circuit
through the FB pin and feeds this voltage back to the
internal transconductance error ampli?er, ERR. The er-
ror ampli?er compares the output voltage to the internal
ratiometric reference, V REF , and outputs an error signal to
the PWM comparator. V REF is set to 0.5 multiplied by the
voltage difference between the R + and R – pins, using an
internal resistor divider.
This error signal is compared with a ?xed frequency
ramp waveform, from the internal oscillator, to generate
a pulse width modulated signal. This PWM signal drives
the external MOSFETs through the TG and BG pins. The
resulting chopped waveform is ?ltered by L O and C OUT
which closes the loop. Loop compensation is achieved
with an external compensation network at the COMP pin,
the output node of the error ampli?er.
MIN, MAX Feedback Loops
Two additional comparators in the feedback loop provide
high speed output voltage correction in situations where
the error ampli?er may not respond quickly enough. MIN
compares the feedback signal to a voltage 3% below V REF .
If the signal is below the comparator threshold, the MIN
comparator overrides the error ampli?er and forces the
loop to maximum duty cycle, >91%. Similarly, the MAX
comparator forces the output to 0% duty cycle if the feed-
3831fb
8
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相关代理商/技术参数 |
参数描述 |
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| LTC3831EGN#PBF | 功能描述:IC SW REG CONTROLLR SYNC 16-SSOP RoHS:是 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 |
| LTC3831EGN#TR | 功能描述:IC SW REG CONTROLLR SYNC 16-SSOP 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 |
| LTC3831EGN#TRPBF | 功能描述:IC SW REG CONTROLLR SYNC 16-SSOP RoHS:是 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 |
| LTC3831EGN-1 | 功能描述:IC CTRLR SW REG SYNC DDR 16SSOP 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 |
| LTC3831EGN-1#PBF | 功能描述:IC CTRLR SW REG SYNC DDR 16SSOP RoHS:是 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 |
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