peaks near fO, th" />
鍙冩暩(sh霉)璩囨枡
鍨嬭櫉锛� LTC1562CG
寤犲晢锛� Linear Technology
鏂囦欢闋佹暩(sh霉)锛� 2/28闋�
鏂囦欢澶�?銆�?/td> 0K
鎻忚堪锛� IC FILTER UNIVRSL RC QUAD 20SSOP
妯欐簴鍖呰锛� 66
婵炬尝鍣ㄩ鍨嬶細 閫氱敤閫g簩(x霉)瑷堟檪
闋荤巼 - 鎴鎴栦腑蹇冿細 150kHz
婵炬尝鍣ㄦ暩(sh霉)锛� 4
婵炬尝鍣ㄩ殠鏁�(sh霉)锛� 8th
闆绘簮闆诲锛� 4.75 V ~ 10.5 V锛�±4.75 V ~ 5.25 V
瀹夎椤炲瀷锛� 琛ㄩ潰璨艰
灏佽/澶栨锛� 20-SSOP锛�0.209"锛�5.30mm 瀵級
渚涙噳鍟嗚ō鍌欏皝瑁濓細 20-SSOP
鍖呰锛� 绠′欢
10
LTC1562
1562fa
Because 2nd order sections with Q
鈮� 1 have response
peaks near fO, the gain ratio above implies some rules of
thumb:
fO < 100kHz V2 tends to have the larger swing
fO > 100kHz V1 tends to have the larger swing.
The following situations are convenient because the
relative swing issue does not arise. The unused output鈥檚
swing is naturally the smaller of the two in these cases:
Lowpass response (resistor input, V2 output, Figure 5)
with fO < 100kHz
Bandpass response (capacitor input, V2 output, Figure
6b) with fO < 100kHz
Bandpass response (resistor input, V1 output, Figure
6a) with fO > 100kHz
Highpass response (capacitor input, V1 output, Figure
7) with fO > 100kHz
The LTC1562-2, a higher frequency derivative of the
LTC1562, has a design center fO of 200kHz compared to
100kHz in the LTC1562. The rules summarized above
apply to the LTC1562-2 but with 200kHz replacing the
100kHz limits. Thus, an LTC1562-2 lowpass filter section
with fO below 200kHz automatically satisfies the desirable
condition of the unused output carrying the smaller signal
swing.
APPLICATIONS INFORMATION
WU
U
level inputs require further dynamic range, reducing the
value of ZIN boosts the signal gain while reducing the input
referred noise. This feature can increase the SNR for low
level signals. Varying or switching ZIN is also an efficient
way to effect automatic gain control (AGC). From a system
viewpoint, this technique boosts the ratio of maximum
signal to minimum noise, for a typical 2nd order lowpass
response (Q = 1, fO = 100kHz), to 118dB.
Input Voltages Beyond the Power Supplies
Properly used, the LTC1562 can accommodate input
voltage excursions well beyond its supply voltage. This
requires care in design but can be useful, for example,
when large out-of-band interference is to be removed from
a smaller desired signal. The flexibility for different input
voltages arises because the INV inputs are at virtual
ground potential, like the inverting input of an op amp with
negative feedback. The LTC1562 fundamentally responds
to input
current and the external voltage VIN appears only
across the external impedance ZIN in Figure 3.
To accept beyond-the-supply input voltages, it is impor-
tant to keep the LTC1562 powered on, not in shutdown
mode, and to avoid saturating the V1 or V2 output of the
2nd order section that receives the input. If any of these
conditions is violated, the INV input will depart from a
virtual ground, leading to an overload condition whose
recovery timing depends on circuit details. In the event
that this overload drives the INV input beyond the supply
voltages, the LTC1562 could be damaged.
The most subtle part of preventing overload is to consider
the possible input signals or spectra and take care that
none of them can drive either V1 or V2 to the supply limits.
Note that neither output can be allowed to saturate, even
if it is not used as the signal output. If necessary the
passband gain can be reduced (by increasing the imped-
ance of ZIN in Figure 3) to reduce output swings.
The final issue to be addressed with beyond-the-supply
inputs is current and voltage limits. Current entering the
virtual ground INV input flows eventually through the
output circuitry that drives V1 and V2. The input current
magnitude (
VIN/ZIN in Figure 3) should be limited by
design to less than 1mA for good distortion performance.
On the other hand, the input voltage VIN appears across the
Low Level or Wide Range Input Signals
The LTC1562 contains a built-in capability for low noise
amplification of low level signals. The ZIN impedance in
each 2nd order section controls the block鈥檚 gain. When set
for unity passband gain, a 2nd order section can deliver an
output signal more than 100dB above the noise level. If low
Figure 8. 100kHz, Q = 0.7 Lowpass Circuit for
Distortion vs Loading Test
INV
V1
2nd ORDER
1/4 LTC1562
V2
1562 F08
R2
10k
CL
30pF
RL
(EXTERNAL
LOAD RESISTANCE)
RQ
6.98k
RIN
10k
VIN
VOUT
鐩搁棞(gu膩n)PDF璩囨枡
PDF鎻忚堪
LTC1562CG-2 IC FILTER UNIVRSL RC QUAD 20SSOP
LTC1562CN#PBF IC FILTER UNIV RC QUAD LN 16DIP
LTC1562CN IC FILTER UNIV RC QUAD LN 16DIP
LTC1562CG#TRPBF IC FILTER UNIV RC QUAD LN 20SSOP
LTC1562CG-2#TRPBF IC FILTER UNIV RC QUAD LN 20SSOP
鐩搁棞(gu膩n)浠g悊鍟�/鎶€琛�(sh霉)鍙冩暩(sh霉)
鍙冩暩(sh霉)鎻忚堪
LTC1562CG#PBF 鍔熻兘鎻忚堪:IC FILTER UNIV RC QUAD LN 20SSOP RoHS:鏄� 椤炲垾:闆嗘垚闆昏矾 (IC) >> 鎺ュ彛 - 婵炬尝鍣� - 鏈夋簮 绯诲垪:- 鐢�(ch菐n)鍝佸煿瑷撴ā濉�:Lead (SnPb) Finish for COTS Obsolescence Mitigation Program 妯欐簴鍖呰:1,000 绯诲垪:- 婵炬尝鍣ㄩ鍨�:閫g簩(x霉)鏅傞枔锛屽付閫氫綆閫� 闋荤巼 - 鎴鎴栦腑蹇�:150kHz 婵炬尝鍣ㄦ暩(sh霉):4 婵炬尝鍣ㄩ殠鏁�(sh霉):8th 闆绘簮闆诲:4.74 V ~ 11 V锛�±2.37 V ~ 5.5 V 瀹夎椤炲瀷:琛ㄩ潰璨艰 灏佽/澶栨:28-SOIC锛�0.295"锛�7.50mm 瀵級 渚涙噳鍟嗚ō鍌欏皝瑁�:28-SOIC W 鍖呰:甯跺嵎 (TR)
LTC1562CG#TR 鍔熻兘鎻忚堪:IC FILTER UNIV RC QUAD LN 20SSOP RoHS:鍚� 椤炲垾:闆嗘垚闆昏矾 (IC) >> 鎺ュ彛 - 婵炬尝鍣� - 鏈夋簮 绯诲垪:- 鐢�(ch菐n)鍝佸煿瑷撴ā濉�:Lead (SnPb) Finish for COTS Obsolescence Mitigation Program 妯欐簴鍖呰:1,000 绯诲垪:- 婵炬尝鍣ㄩ鍨�:閫g簩(x霉)鏅傞枔锛屽付閫氫綆閫� 闋荤巼 - 鎴鎴栦腑蹇�:150kHz 婵炬尝鍣ㄦ暩(sh霉):4 婵炬尝鍣ㄩ殠鏁�(sh霉):8th 闆绘簮闆诲:4.74 V ~ 11 V锛�±2.37 V ~ 5.5 V 瀹夎椤炲瀷:琛ㄩ潰璨艰 灏佽/澶栨:28-SOIC锛�0.295"锛�7.50mm 瀵級 渚涙噳鍟嗚ō鍌欏皝瑁�:28-SOIC W 鍖呰:甯跺嵎 (TR)
LTC1562CG#TRPBF 鍔熻兘鎻忚堪:IC FILTER UNIV RC QUAD LN 20SSOP RoHS:鏄� 椤炲垾:闆嗘垚闆昏矾 (IC) >> 鎺ュ彛 - 婵炬尝鍣� - 鏈夋簮 绯诲垪:- 鐢�(ch菐n)鍝佸煿瑷撴ā濉�:Lead (SnPb) Finish for COTS Obsolescence Mitigation Program 妯欐簴鍖呰:1,000 绯诲垪:- 婵炬尝鍣ㄩ鍨�:閫g簩(x霉)鏅傞枔锛屽付閫氫綆閫� 闋荤巼 - 鎴鎴栦腑蹇�:150kHz 婵炬尝鍣ㄦ暩(sh霉):4 婵炬尝鍣ㄩ殠鏁�(sh霉):8th 闆绘簮闆诲:4.74 V ~ 11 V锛�±2.37 V ~ 5.5 V 瀹夎椤炲瀷:琛ㄩ潰璨艰 灏佽/澶栨:28-SOIC锛�0.295"锛�7.50mm 瀵級 渚涙噳鍟嗚ō鍌欏皝瑁�:28-SOIC W 鍖呰:甯跺嵎 (TR)
LTC1562CG-2 鍔熻兘鎻忚堪:IC FILTER UNIVRSL RC QUAD 20SSOP RoHS:鍚� 椤炲垾:闆嗘垚闆昏矾 (IC) >> 鎺ュ彛 - 婵炬尝鍣� - 鏈夋簮 绯诲垪:- 鐢�(ch菐n)鍝佸煿瑷撴ā濉�:Lead (SnPb) Finish for COTS Obsolescence Mitigation Program 妯欐簴鍖呰:1,000 绯诲垪:- 婵炬尝鍣ㄩ鍨�:閫g簩(x霉)鏅傞枔锛屽付閫氫綆閫� 闋荤巼 - 鎴鎴栦腑蹇�:150kHz 婵炬尝鍣ㄦ暩(sh霉):4 婵炬尝鍣ㄩ殠鏁�(sh霉):8th 闆绘簮闆诲:4.74 V ~ 11 V锛�±2.37 V ~ 5.5 V 瀹夎椤炲瀷:琛ㄩ潰璨艰 灏佽/澶栨:28-SOIC锛�0.295"锛�7.50mm 瀵級 渚涙噳鍟嗚ō鍌欏皝瑁�:28-SOIC W 鍖呰:甯跺嵎 (TR)
LTC1562CG-2#PBF 鍔熻兘鎻忚堪:IC FILTER UNIV RC QUAD LN 20SSOP RoHS:鏄� 椤炲垾:闆嗘垚闆昏矾 (IC) >> 鎺ュ彛 - 婵炬尝鍣� - 鏈夋簮 绯诲垪:- 鐢�(ch菐n)鍝佸煿瑷撴ā濉�:Lead (SnPb) Finish for COTS Obsolescence Mitigation Program 妯欐簴鍖呰:1,000 绯诲垪:- 婵炬尝鍣ㄩ鍨�:閫g簩(x霉)鏅傞枔锛屽付閫氫綆閫� 闋荤巼 - 鎴鎴栦腑蹇�:150kHz 婵炬尝鍣ㄦ暩(sh霉):4 婵炬尝鍣ㄩ殠鏁�(sh霉):8th 闆绘簮闆诲:4.74 V ~ 11 V锛�±2.37 V ~ 5.5 V 瀹夎椤炲瀷:琛ㄩ潰璨艰 灏佽/澶栨:28-SOIC锛�0.295"锛�7.50mm 瀵級 渚涙噳鍟嗚ō鍌欏皝瑁�:28-SOIC W 鍖呰:甯跺嵎 (TR)