收藏本站
LTC1799
6
1799fc
Theory oF operaTion
As shown in the Block Diagram, the LTC1799’s master
oscillator is controlled by the ratio of the voltage between
the V+ and SET pins and the current entering the SET pin
(IRES).ThevoltageontheSETpinisforcedtoapproximately
1.13V below V+ by the PMOS transistor and its gate bias
voltage. This voltage is accurate to ±7% at a particular
input current and supply voltage (see Figure 1). The ef-
fective input resistance is approximately 2k.
A resistor RSET, connected between the V+ and SET pins,
“locks together” the voltage (V+ – VSET) and current, IRES,
variation. This provides the LTC1799’s high precision. The
master oscillation frequency reduces to:
MO =10MHz
10k
RSET
The LTC1799 is optimized for use with resistors between
10kand200k,correspondingtomasteroscillatorfrequen-
ciesbetween0.5MHzand10MHz.Accuratefrequenciesup
to 20MHz (RSET = 5k) are attainable if the supply voltage
is greater than 4V.
Toextendtheoutputfrequencyrange,themasteroscillator
signal may be divided by 1, 10 or 100 before driving OUT
Figure 2. RSET vs Desired Output Frequency
(Pin 5). The divide-by value is determined by the state of
the DIV input (Pin 4). Tie DIV to GND or drive it below 0.5V
to select ÷1. This is the highest frequency range, with the
master output frequency passed directly to OUT. The DIV
pin may be floated or driven to midsupply to select ÷10,
the intermediate frequency range. The lowest frequency
range, ÷100, is selected by tying DIV to V+ or driving it to
within 0.4V of V+. Figure 2 shows the relationship between
RSET, divider setting and output frequency, including the
overlapping frequency ranges near 100kHz and 1MHz.
The CMOS output driver has an on resistance that is typi-
cally less than 100Ω. In the ÷1 (high frequency) mode,
the rise and fall times are typically 7ns with a 5V supply
and 11ns with a 3V supply. These times maintain a clean
square wave at 10MHz (20MHz at 5V supply). In the ÷10
and÷100modes,wheretheoutputfrequencyismuchlower,
slew rate control circuitry in the output driver increases
the rise/fall times to typically 14ns for a 5V supply and
19ns for a 3V supply. The reduced slew rate lowers EMI
(electromagnetic interference) and supply bounce.
Figure 1. V+ – VSET Variation with IRES
IRES (A)
1
0.8
V RES
=
V
+ –
V
SET
1.2
1.3
1.4
10
100
1000
1799 F01
1.1
1.0
0.9
V+ = 5V
V+ = 3V
TA = 25°C
DESIRED OUTPUT FREQUENCY (Hz)
10
R
SET
(k)
100
1k
100k
1M
10M
1799 F02
1
10k
1000
100M
÷100
÷10
÷1
MOST
ACCURATE
OPERATION
发布紧急采购，3分钟左右您将得到回复。

采购需求

(若只采购一条型号，填写一行即可)

发布成功！您可以继续发布采购。也可以进入我的后台，查看报价

发布成功！您可以继续发布采购。也可以进入我的后台，查看报价

*型号 *数量 厂商 批号 封装
添加更多采购

我的联系方式

*
*
*
相关PDF资料
LTC1821ACGW IC D/A CONV 16BIT PRECISE 36SSOP
LTC1851CFW IC ADC 12BIT 1.25MSPS 48-TSSOP
LTC1853IFW#TRPBF IC A/D CONV 8CH 12BIT 48-TSSOP
LTC1856IG#PBF IC ADC 16BIT 100KSPS 28-SSOP
LTC1859IG#TRPBF IC A/D CONV 8CH 16BIT 28-SSOP
LTC1867AIGN#TRPBF IC ADC 16BIT 8CH 200KSPS 16SSOP
LTC1867LCGN#PBF IC ADC 16BIT 8CH 175KSPS 16SSOP
LTC2142IUP-14#PBF IC ADC DUAL 14BIT 65MSPS 64QFN
相关代理商/技术参数
LTC1799HS5TRMPBF 制造商:Linear Technology 功能描述:Resistor Set Oscillator 33MHz TSOT23-5
LTC1799IS5 制造商:Linear Technology 功能描述:1KHZ TO 33MHZ RESISTOR SET SOT-23 OSCILLATOR 制造商:Linear Technology 功能描述:Silicon Oscillator 5-Pin TSOT-23
LTC1799IS5#PBF 制造商:Linear Technology 功能描述:1KHZ TO 33MHZ RESISTOR SET SOT-23 OSCILLATOR 制造商:Linear Technology 功能描述:IC, OSCILLATOR; Operating Mode:-; Frequency:33MHz; Supply Voltage Min:2.7V; Supply Voltage Max:5.5V; Digital IC Case Style:TSOT-23; No. of Pins:5; Clock External Input:No; Operating Temperature Min:-40C; MSL:MSL 1 - Unlimited ;RoHS Compliant: Yes
LTC1799IS5#TR 功能描述:IC OSC SILICON 33MHZ TSOT23-5 RoHS:否 类别:集成电路 (IC) >> 时钟/计时 - 可编程计时器和振荡器 系列:- 产品培训模块:Lead (SnPb) Finish for COTS Obsolescence Mitigation Program 标准包装:45 系列:- 类型:温度 - 补偿晶体振荡器（TCXO） 计数:- 频率:25MHz 电源电压:3.135 V ~ 3.465 V 电流 - 电源:1.5mA 工作温度:-40°C ~ 85°C 封装/外壳:16-SOIC（0.295"，7.50mm 宽） 包装:管件 供应商设备封装:16-SOIC W 安装类型:表面贴装
LTC1799IS5#TRM 功能描述:IC OSC SILICON 33MHZ TSOT23-5 RoHS:否 类别:集成电路 (IC) >> 时钟/计时 - 可编程计时器和振荡器 系列:- 产品培训模块:Lead (SnPb) Finish for COTS Obsolescence Mitigation Program 标准包装:45 系列:- 类型:温度 - 补偿晶体振荡器（TCXO） 计数:- 频率:25MHz 电源电压:3.135 V ~ 3.465 V 电流 - 电源:1.5mA 工作温度:-40°C ~ 85°C 封装/外壳:16-SOIC（0.295"，7.50mm 宽） 包装:管件 供应商设备封装:16-SOIC W 安装类型:表面贴装
LTC1799IS5#TRMPBF 功能描述:IC OSC SILICON 33MHZ TSOT23-5 RoHS:是 类别:集成电路 (IC) >> 时钟/计时 - 可编程计时器和振荡器 系列:- 标准包装:3,000 系列:- 类型:振荡器 - 晶体 计数:- 频率:- 电源电压:2.3 V ~ 5.5 V 电流 - 电源:1.07mA 工作温度:-30°C ~ 80°C 封装/外壳:SOT-665 包装:带卷 (TR) 供应商设备封装:SS迷你型-5D 安装类型:表面贴装 其它名称:AN8955SSMTXLTR
LTC1799IS5#TRPBF 功能描述:IC OSC SILICON 33MHZ TSOT23-5 RoHS:是 类别:集成电路 (IC) >> 时钟/计时 - 可编程计时器和振荡器 系列:- 产品培训模块:Lead (SnPb) Finish for COTS Obsolescence Mitigation Program 标准包装:45 系列:- 类型:温度 - 补偿晶体振荡器（TCXO） 计数:- 频率:25MHz 电源电压:3.135 V ~ 3.465 V 电流 - 电源:1.5mA 工作温度:-40°C ~ 85°C 封装/外壳:16-SOIC（0.295"，7.50mm 宽） 包装:管件 供应商设备封装:16-SOIC W 安装类型:表面贴装
LTC1799IS5TRMPBF 制造商:Linear Technology 功能描述:Oscillator 1-33KHz Resistor Set TSOT23-5