THS4521 Datasheet, PDF (32/43 Pages) Texas Instruments – VERY LOW POWER, NEGATIVE RAIL INPUT, RAIL-TO-RAIL OUTPUT, FULLY DIFFERENTIAL AMPLIFIER

THS4521
THS4522
THS4524
SBOS458B – DECEMBER 2008 – REVISED MAY 2009.................................................................................................................................................... www.ti.com
EVM AND LAYOUT RECOMMENDATIONS
Figure 77 shows the THS4521EVM schematic. PCB layers 1 through 4 are shown in Figure 78; Table 6 lists the
bill of materials for the THS4521EVM as supplied from TI. It is recommended to follow the layout of the external
components near to the amplifier, ground plane construction, and power routing as closely as possible. Follow
these general guidelines:
1. Signal routing should be direct and as short as possible into and out of the op amp circuit.
2. The feedback path should be short and direct.
3. Ground or power planes should be removed from directly under the amplifier input and output pins.
4. An output resistor is recommended in each output lead, placed as near to the output pins as possible.
5. Two 0.1-µF power-supply decoupling capacitors should be placed as near to the power-supply pins as
possible.
6. Two 10-µF power-supply decoupling capacitors should be placed within 1 inch of the device and can be
shared among multple analog devices.
7. A 0.22-µF capacitor should be placed between the V_OCM input pin and ground near to the pin. This capacitor
limits noise coupled into the pin.
8. The PD pin uses TTL logic levels; a bypass capacitor is not necessary if actively driven, but can be used for
robustness in noisy environments whether driven or not.
9. If input termination resistors R₁₀ and R₁₁ are used, a single point connection to ground on L2 is
recommended.
J4
J5
J8
V_S-
V_S-
GND
V_S+
V_S+
V_S+
C₃
0.1mF
C603
C₅
0.1mF
C₇
10mF
C₈
10mF
C0805
C₉
10mF
C0805
C₁₀
10mF
C₁₁
0.1mF
C₁₂
0.1mF
C603
C₁₃
Open
C₁₄
Open
C₁₅
Open
C₁₆
Open
C₁
R₆
0.22mF 49.9W
J1
R₄
0W
R₁
3 T1 4
R₃
2
5
R₇
R₂
1
6
R₅
0W
J2
C₂
R₈
R₁₀
52.3W
R₉
R₁₁
52.3W
J11
C₄
0.22mF
JP1
V_S-
R₁₂
1kW
R₁₃
1kW
R₁₄
1kW
PW _VS-
7
R₁₈
V_OUT+
1
6
4
5
8
3
2
V_S+
CM
R₁₅
1kW
V_OUT-
R₁₉
J6
R₁₆
487W
R₂₀
52.3W
R₁₇
487W
J7
TP1
C₆
J3
0.22mF
TP2 TP3
V_S-
R₂₃
6 T2 1
R₂₁
5
2
R₂₂
4
3
R₂₄
0W
R₂₅
0W
J9
R₂₆
J10
Figure 77. THS4521EVM: Schematic
32
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