ISL1539AIRZ-T13 [INTERSIL]

Dual Port VDSL2 Line Driver;
ISL1539AIRZ-T13
型号: ISL1539AIRZ-T13
厂家: Intersil    Intersil
描述:

Dual Port VDSL2 Line Driver

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中文:  中文翻译
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Dual Port VDSL2 Line Driver  
ISL1539A  
Features  
• 360mA Output Drive Capability  
The ISL1539A provides 4 internal wideband op amps  
intended to be used as two pairs of differential line  
drivers. The ISL1539A’s high bandwidth, 240MHz, and  
• 41.8V Differential Output Drive into 100Ω  
P-P  
• -89dBc THD @ 1MHz 2V  
P-P  
ultra low distortion, -89dBc @ 1MHz, 2V , support the  
P-P  
• -65dBc MTPR (VDSL 8b Profile)  
demanding MTPR requirements of emerging VDSL2 line  
driver designs. Less demanding requirements can be met  
at very low quiescent powers using the supply current  
adjustment features.  
• High Slew Rate of 3000V/µs Differential  
• Bandwidth (240MHz @ A  
V-DIFF  
• Supply Current Control Pins  
• Port Separation  
- 78dB @ 500kHz  
- 70dB @ 1MHz  
- 60dB @ 4MHz  
= 10)  
Each of the 4 internal op amps is a wideband current  
feedback amplifier offering very high slew rate intrinsic to  
that design using low quiescent current levels. Each of  
the two pair of amplifiers (ports) can also be power  
optimized to the application using two external quiescent  
control logic pins. Full power is nominally 27.2mA/port  
with options of medium power cutback to 23mA/port, a  
low power condition at 13.5mA/port, and an off state at  
<0.5mA/port. Added quiescent power flexibility is  
• Pb-Free (RoHS Compliant)  
Applications*(see page 21)  
• 8MHz and 17MHz VDSL2 Profiles  
• ADSL2+  
provided through an external I  
pin. Grounding the pin  
ADJ  
gives the nominal currents listed above while inserting a  
resistor from this pin to ground can be used to scale each  
of the settings downward.  
Related Literature (see Device Info page)  
• AN1325 “Choosing and Using Bypass Capacitors”  
High power push/pull line driver applications as  
illustrated in the example below are best supported using  
a low headroom, high output current device. On ±12V  
supplies, the ISL1539A offers a 1.1V headroom with  
>360mA peak output current. Driving differentially this  
• TB426 “Characterization of the Output Protection  
Circuitry of the EL1528 DSL Driver for Lightning  
Surges”  
TABLE 1. ALTERNATE SOLUTIONS  
gives >41.8V  
swing to as low as 58Ω differential load.  
P-P  
High SFDR operation is also supported for supplies as low  
as ±7.5V. Intended to be used as differential pairs, this  
two port device includes special circuitry to minimize  
common mode loop peaking while also reducing the  
common mode output noise spectrum. That circuitry  
links the two sides of each port, precluding their  
application as individual amplifiers.  
NOMINAL ±V  
(V)  
BANDWIDTH  
(MHz)  
CC  
PART #  
ISL1557  
ISL1534  
ISL1536  
APPLICATIONS  
VDSL  
±6  
200  
40  
±12  
±12  
ADSL2+  
50  
ADSL2+  
Typical Application  
4MHz Harmonic Distortion  
+12V  
V
= ±12V  
S
+
AV = +10  
¼
Ro  
Rb  
ISL1539A  
R
R
= 3.2kΩ  
F
L
-
= 100Ω DIFF  
Rf  
1:n  
Ω
3.2k  
Ω
VI  
VO  
Rg711  
LOAD  
SOURCE  
3rd HD  
THD  
Rf  
2nd HD  
3.2kΩ  
-
¼
ISL1539A  
+
Ro  
AV-DIFF = VO/VI = 10V/V  
Rb  
-12V  
TYPICAL DIFFERENTIAL I/O LINE DRIVER  
(1 OF 2 PORTS)  
September 23, 2009  
FN6916.0  
CAUTION: These devices are sensitive to electrostatic discharge; follow proper IC Handling Procedures.  
1-888-INTERSIL or 1-888-468-3774 | Intersil (and design) is a registered trademark of Intersil Americas Inc.  
Copyright © Intersil Americas Inc. 2009. All Rights Reserved.  
1
All other trademarks mentioned are the property of their respective owners.  
ISL1539A  
Pin Configurations  
ISL1539A  
(24 LD HTSSOP)  
TOP VIEW  
ISL1539A  
(24 LD QFN)  
TOP VIEW  
VS- 1  
C0AB 2  
C1AB 3  
VINA+ 4  
VINB+ 5  
GND 6  
24 VS+  
+
-
23 VOUTA  
22 VINA-  
21 VINB-  
20 VOUTB  
19 NC  
VINA+ 1  
VINB+ 2  
GND 3  
19 VINA-  
+
-
18 VINB-  
-
+
17 VOUTB  
16 NC/SHIELD  
15 VOUTC  
14 VINC-  
-
+
IADJ 4  
IADJ 7  
18 NC  
+
-
NC 5  
+
-
VINC+ 8  
VIND+ 9  
C1CD 10  
C0CD 11  
VS- 12  
17 VOUTC  
16 VINC-  
15 VIND-  
14 VOUTD  
13 VS+  
VINC+ 6  
VIND+ 7  
-
+
13 VIND-  
-
+
VS- 1  
C0AB 2  
C1AB 3  
VINA+ 4  
VINB+ 5  
GND 6  
24 VS+  
23 VOUTA  
22 VINA-  
21 VINB-  
20 VOUTB  
19 NC  
VINA+ 1  
VINB+ 2  
GND 3  
19 VINA-  
18 VINB-  
17 VOUTB  
16 NC/SHIELD  
15 VOUTC  
14 VINC-  
THERMAL  
PAD  
THERMAL  
PAD  
IADJ 4  
IADJ 7  
18 NC  
NC 5  
VINC+ 8  
VIND+ 9  
C1CD 10  
C0CD 11  
VS- 12  
17 VOUTC  
16 VINC-  
15 VIND-  
14 VOUTD  
13 VS+  
VINC+ 6  
VIND+ 7  
13 VIND-  
THERMAL PAD CONNECTS TO GND OR -V  
THERMAL PAD CONNECTS TO GND OR -V  
S
S
Pin Descriptions  
ISL1539AIR  
ISL1539AIV  
(24 Ld QFN) (24 Ld HTSSOP)  
PIN NAME  
VINA+  
VINB+  
GND  
FUNCTION  
CIRCUIT  
1
2
3
4
4
5
6
7
Amplifier A non-inverting input (Refer to Circuit 1)  
Amplifier B non-inverting input (Refer to Circuit 1)  
Ground connection  
IADJ  
Supply current control pin for  
both DSL Port #1 and #2  
(Refer to Figure 46)  
5
18, 19  
8
NC  
Not connected  
6
VINC+  
VIND+  
C1CD  
C0CD  
VS-  
Amplifier C non-inverting input (Refer to Circuit 1)  
Amplifier D non-inverting input (Refer to Circuit 1)  
DSL Port #2 current control pin (Refer to Figure 46)  
DSL Port #2 current control pin (Refer to Figure 46)  
Negative supply  
7
8
9
10  
9
11  
10, 22  
11, 21  
12  
1, 12  
13, 24  
14  
VS+  
Positive supply  
VOUTD  
Amplifier D output  
(Refer to Circuit 2)  
FN6916.0  
September 23, 2009  
2
ISL1539A  
Pin Descriptions(Continued)  
ISL1539AIR  
ISL1539AIV  
(24 Ld QFN) (24 Ld HTSSOP)  
PIN NAME  
VIND-  
FUNCTION  
CIRCUIT  
(Refer to Circuit 3)  
(Refer to Circuit 3)  
(Refer to Circuit 2)  
13  
14  
15  
16  
17  
18  
19  
20  
23  
24  
-
15  
16  
17  
18, 19  
20  
21  
22  
23  
2
Amplifier D Inverting Input  
Amplifier C Inverting Input  
Amplifier C output  
VINC-  
VOUTC  
NC/SHIELD  
VOUTB  
Not Connected  
Amplifier B output  
(Refer to Circuit 2)  
(Refer to Circuit 3)  
(Refer to Circuit 3)  
(Refer to Circuit 2)  
VINB-  
Amplifier B Inverting Input  
Amplifier A Inverting Input  
Amplifier A output  
VINA-  
VOUTA  
C0AB  
DSL Port #1 current control pin (Refer to Figure 46)  
DSL Port #1 current control pin (Refer to Figure 46)  
3
C1AB  
-
THERMAL PAD  
Connects to GND or -V  
S
V +  
V +  
S
S
V +  
S
V +  
S
V -  
S
V -  
V -  
S
S
CIRCUIT 1  
CIRCUIT 2  
V -  
S
CIRCUIT 3  
Ordering Information  
OPERATING AMBIENT  
TEMP RANGE  
(°C)  
PART  
NUMBER  
PART  
MARKING  
PACKAGE  
(Pb-free)  
PKG.  
DWG. #  
ISL1539AIRZ (Note 2)  
1539A IRZ  
-40 to +85  
-40 to +85  
24 Ld QFN  
24 Ld QFN  
L24.4x5B  
ISL1539AIRZ-T13 (Notes 1, 2) 1539A IRZ  
L24.4x5B  
MDP0048  
MDP0048  
COMING SOON  
ISL1539AIVEZ (Note 2)  
1539A IVEZ  
-40 to +85  
-40 to +85  
24 Ld HTSSOP  
24 Ld HTSSOP  
COMING SOON  
ISL1539AIVEZ-T13 (Notes 1, 2) 1539A IVEZ  
NOTES:  
1. Please refer to TB347 for details on reel specifications.  
2. These Intersil Pb-free plastic packaged products employ special Pb-free material sets, molding compounds/die attach  
materials, and 100% matte tin plate plus anneal (e3 termination finish, which is RoHS compliant and compatible with both  
SnPb and Pb-free soldering operations). Intersil Pb-free products are MSL classified at Pb-free peak reflow temperatures that  
meet or exceed the Pb-free requirements of IPC/JEDEC J STD-020.  
3. For Moisture Sensitivity Level (MSL), please see device information page for ISL1539A. For more information on MSL please  
see techbrief TB363.  
FN6916.0  
September 23, 2009  
3
ISL1539A  
Absolute Maximum Ratings (T = +25°C)  
Thermal Information  
A
V + to V - Supply Voltage . . . . . . . . . . . . -0.3V to +26.4V  
Thermal Resistance (Typical)  
θJA (°C/W) θJC (°C/W)  
S
S
V + Voltage to GND . . . . . . . . . . . . . . . . . -0.3V to +26.4V  
S
24 Ld QFN Package (Notes 4, 5) . .  
24 Ld HTSSOP Package (Notes 4, 5)  
39  
4.5  
V - Voltage to GND . . . . . . . . . . . . . . . . . -26.4V to +0.3V  
S
TBD  
TBD  
Driver V + Voltage . . . . . . . . . . . . . . . . . . . . . V - to V +  
IN  
S
S
Maximum Junction Temperature (Plastic Package). . . +150°C  
Current into any Input. . . . . . . . . . . . . . . . . . . . . . . . 8mA  
Continuous Output Current for Long Term Reliability . . . . 50mA  
Power Dissipation. . . . . . . . . . . . . . . . . . . . . . . See Figure 42  
Storage Temperature Range. . . . . . . . . . . -40°C to +150°C  
Pb-Free Reflow Profile . . . . . . . . . . . . . . . . . .see link below  
http://www.intersil.com/pbfree/Pb-FreeReflow.asp  
C , C Voltage to GND . . . . . . . . . . . . . . . . . .-0.3V to +6V  
0
1
I
Voltage to GND . . . . . . . . . . . . . . . . . . . . . -1V to +4V  
ESD Rating  
ADJ  
Machine Model . . . . . . . . . . . . . . . . . . . . . . . . . . . 200V  
Human Body Model (Per MIL-STD-883 Method 3015.7). . 3kV  
Charge Device Model . . . . . . . . . . . . . . . . . . . . . . 1.5kV  
Operating Conditions  
Ambient Temperature Range . . . . . . . . . . . .-40°C to +85°C  
Junction Temperature Range . . . . . . . . . . . -40°C to +150°C  
CAUTION: Do not operate at or near the maximum ratings listed for extended periods of time. Exposure to such conditions may adversely impact  
product reliability and result in failures not covered by warranty.  
NOTES:  
4. θ is measured with the component mounted on a high effective thermal conductivity test board in free air. QFN and HTSSOP  
JA  
exposed pad soldered to PCB per JESD51-5. See Tech Brief TB379 for details.  
5. For θ , the “case temp” location is the center of the exposed metal pad on the package underside.  
JC  
IMPORTANT NOTE: All parameters having Min/Max specifications are guaranteed. Typ values are for information purposes only. Unless otherwise  
noted, all tests are at the specified temperature and are pulsed tests, therefore: T = T = T  
J
C
A
Electrical Specifications V = ±12V, R = 100Ω differential, I  
= C = C = 0V, A = 10V/V, R = 3.2kΩ,  
0 1 V F  
S
L
ADJ  
T = +25°C. Amplifier pairs tested separately unless otherwise indicated.  
A
PARAMETER  
DESCRIPTION  
CONDITIONS  
MIN  
TYP  
MAX  
UNIT  
AC PERFORMANCE  
BW  
-3dB Small Signal Bandwidth V < 2V  
A = 10  
V
240  
120  
100  
3000  
-93  
-90  
-88  
-91  
-109  
-91  
-87  
-95  
-86  
-70  
MHz  
MHz  
MHz  
V/µs  
dBc  
dBc  
dBc  
dBc  
dBc  
dBc  
dBc  
dBc  
dBc  
dBc  
O
P-P-DIFF,  
P-P-DIFF  
V
< 2V  
(Note 6)  
O
-3dB Large Signal Bandwidth V = 10V  
O
P-P-DIFF  
SR  
20% to 80%  
V
V
V
V
V
V
V
V
V
V
= 32V  
2000  
O
P-P-DIFF  
200kHzHarmonic 2nd Harmonic  
Distortion  
= 10V  
OUT  
OUT  
OUT  
OUT  
OUT  
OUT  
OUT  
OUT  
OUT  
P-P-DIFF  
P-P-DIFF  
P-P-DIFF  
P-P-DIFF  
P-P-DIFF  
P-P-DIFF  
P-P-DIFF  
P-P-DIFF  
P-P-DIFF  
3rd Harmonic  
= 10V  
= 10V  
THD  
1MHz Harmonic  
Distortion  
2nd Harmonic  
3rd Harmonic  
THD  
= 2V  
= 2V  
= 2V  
= 2V  
= 2V  
= 2V  
8MHz Harmonic  
Distortion  
2nd Harmonic  
3rd Harmonic  
THD  
MTPR  
Multi-Tone Power Ratio  
26kHz to 8MHz, 4kHz Tone Spacing,  
= 19dBm, VDSL2+ 8b (Note 6)  
P
LINE  
200kHzHarmonic 2nd Harmonic  
V
V
V
= 10V  
= 10V  
= 10V  
(Note 6)  
(Note 6)  
(Note 6)  
-93  
-90  
-88  
dBc  
dBc  
dBc  
OUT  
OUT  
OUT  
P-P-DIFF  
P-P-DIFF  
P-P-DIFF  
Distortion  
3rd Harmonic  
THD  
FN6916.0  
September 23, 2009  
4
ISL1539A  
Electrical Specifications V = ±12V, R = 100Ω differential, I  
= C = C = 0V, A = 10V/V, R = 3.2kΩ,  
0 1 V F  
S
L
ADJ  
T = +25°C. Amplifier pairs tested separately unless otherwise indicated. (Continued)  
A
PARAMETER  
DESCRIPTION  
2nd Harmonic  
CONDITIONS  
MIN  
TYP  
MAX  
UNIT  
4MHz Harmonic  
Distortion  
V
= 10V  
-72  
dBc  
OUT  
(Note 6)  
P-P-DIFF  
P-P-DIFF  
P-P-DIFF  
3rd Harmonic  
THD  
V
= 10V  
-70  
-68  
dBc  
dBc  
OUT  
(Note 6)  
V
= 10V  
OUT  
(Note 6)  
8MHz Harmonic  
Distortion  
2nd Harmonic  
3rd Harmonic  
THD  
V
V
V
= 2V  
= 2V  
= 2V  
(Note 6)  
-83  
-78  
-76  
4.0  
dBc  
dBc  
OUT  
OUT  
OUT  
P-P-DIFF  
P-P-DIFF  
P-P-DIFF  
(Note 6)  
(Note 6)  
dBc  
e
Non-Inverting Input Voltage f = 1MHZ  
Noise at each of the 4 Inputs  
nV/Hz  
N
+i  
Non-Inverting Input Current f = 1MHZ  
Noise at each of the 4 Inputs  
2.7  
23  
90  
pA/Hz  
pA/Hz  
nV/Hz  
N
-i  
Inverting Input Current Noise f = 1MHZ  
at each of the 4 Inputs  
N
e
Common Mode Output Noise f = 1MHZ  
at each Port Pair  
N-CM  
POWER CONTROL FEATURES  
V
V
Logic High Voltage  
Logic Low Voltage  
C and C inputs  
2.0  
V
V
IH  
IL  
0
1
C and C inputs  
0.8  
+5  
0
1
I
I
I
I
Logic High Current for C  
C
C = 3.3V, C = 3.3V  
-5  
1
µA  
µA  
Ω
IH0 , IH1  
0,  
1
0
1
I
Logic Low Current for C or C C = 0V, C = 0V  
-17  
-13  
500  
-10  
IL0, IL1  
0
1
0
1
Input Resistance  
ADJ  
SUPPLY CHARACTERISTICS  
Maximum Operating Supply  
Voltage  
±12.6  
±7.5  
V
V
Minimum Operating Supply  
Voltage  
I
GND Pin Current per Port  
All outputs at 0V (Note 7)  
All outputs at 0V, C = C = 0V, No  
0.2  
21  
0.4  
0.5  
mA  
mA  
GND  
I + (Full Power) Positive Supply Current per  
S
27.2  
31.5  
0
1
Port  
Load  
I + (Medium)  
Positive Supply Current per  
Port  
All outputs at 0V, C = 3.3V, C = 0V,  
No Load  
17.8  
10.4  
0.2  
23  
13.5  
0.4  
26.7  
15.6  
0.5  
mA  
mA  
mA  
S
0
1
I + (Low)  
Positive Supply Current per  
Port  
All outputs at 0V, C = 0V, C = 3.3V,  
S
0
1
No Load  
I + (Power-down) Positive Supply Current per  
S
All outputs at 0V, C = C = 3.3V, No  
0
1
Port  
Load  
OUTPUT CHARACTERISTICS  
V
Output Swing  
R
R
R
R
R
= No Load  
= 100Ω  
= 100Ω  
= 60Ω  
±10.7  
+10.3  
±10.9  
+10.5  
-10.4  
+9.8  
-9.7  
V
V
OUT  
L-DIFF  
L-DIFF  
L-DIFF  
L-DIFF  
L-DIFF  
Lightly Loaded Positive Swing  
Lightly Loaded Negative Swing  
Heavy Loaded Positive Swing  
Heavy Loaded Negative Swing  
Linear Output Current  
-10.2  
-9.3  
V
+9.4  
V
= 60Ω  
V
I
R = 25Ω, f = 100kHz, THD = -60dBc  
±360  
mA  
OL  
L
FN6916.0  
September 23, 2009  
5
ISL1539A  
Electrical Specifications V = ±12V, R = 100Ω differential, I  
= C = C = 0V, A = 10V/V, R = 3.2kΩ,  
0 1 V F  
S
L
ADJ  
T = +25°C. Amplifier pairs tested separately unless otherwise indicated. (Continued)  
A
PARAMETER  
DESCRIPTION  
CONDITIONS  
= ±1V, R = 1Ω  
MIN  
TYP  
MAX  
UNIT  
I
Peak Output Current  
V
±600  
mA  
OUT  
OUT  
L
INPUT CHARACTERISTICS  
Input Offset Voltage  
Input V Mismatch  
V
-8  
-2  
+3.5  
0
+8  
+2  
mV  
mV  
OS  
ΔV  
OS  
OS  
Between Amplifiers for Each  
Port  
V
Input V  
OS  
Drift  
-25°C to +125°C T  
±15  
µV/°C  
µA  
OS, DRIFT  
J
I +  
Non-Inverting Input Bias  
Current  
-8  
-2  
+8  
+2  
B
ΔI +  
Non-Inverting I + Mismatch  
B
µA  
B
Between Amplifiers for Each  
Port  
I +  
Non-Inverting I + Drift  
B
-25°C to +125°C T  
-25°C to +125°C T  
±12  
nA/°C  
µA  
B
, DRIFT  
J
I -  
Inverting Input Bias Current  
-75  
-35  
+75  
+35  
B
ΔI -  
Inverting I - Mismatch  
B
Between Amplifiers for Each  
Port  
µA  
B
I -  
B , DRIFT  
Inverting I - Drift  
B
±25  
nA/°C  
V
J
CMIR  
Common Mode Input Range  
at each of the 4  
±7.5  
Non-Inverting Input Pins  
CMRR  
Common Mode Rejections for  
V
to Differential Mode Output  
80  
43  
dB  
dB  
CM  
each Port. V  
= -5V to +5V (Input Referred)  
CM  
V
to Commonl Mode Output  
CM  
(Output Referred)  
PSRR  
Power Supply Rejections for +V = +7.5V to +12V, -V = -12V  
97  
92  
dB  
dB  
S
S
each Port to Differential  
Output (Input Referred)  
-V = -7.5V to -12V, +V = +12V  
S
S
Power Supply Rejections for +V = +7.5V to +12V, -V = -12V  
51  
45  
dB  
dB  
S
S
each Port to Common Mode  
Output (Output Referred)  
-V = -7.5V to -12V, +V = +12V  
S
S
NOTES:  
6. Active Termination Test Circuit. Low Power Mode (see Figure 45).  
7. The -V supply current is the +V supply current minus the ground current, except power down condition.  
S
S
FN6916.0  
September 23, 2009  
6
ISL1539A  
Typical Performance Curves  
V
= ±12V, R = 3.2kΩ, G = 10V/V (differential), R  
LOAD  
= 100Ω, T +25°C, C0 = C1 = I  
= 0V (full power),  
CC  
F
D
A
ADJ  
unless otherwise noted.  
9
V
= 0.5V  
2V  
O
P-P  
P-P  
6
3
5V  
AV = 10, R = 3.2kΩ  
P-P  
F
AV = 20, R = 2.5kΩ  
F
A
= 10  
V
0.5V  
P-P  
10V  
20V  
P-P  
AV = 40, R = 2.4kΩ  
F
0
-3  
-6  
-9  
-12  
P-P  
A
= 40  
V
A
= 20  
V
1M  
10M  
100M  
1G  
FREQUENCY (Hz)  
FIGURE 1. SMALL SIGNAL FREQUENCY RESPONSE vs  
GAIN  
FIGURE 2. LARGE SIGNAL FREQUENCY RESPONSE  
3rd HD  
2nd HD  
2nd HD  
THD  
THD  
3rd HD  
FIGURE 3. 1MHz HARMONIC DISTORTION vs  
OUTPUT SWING  
FIGURE 4. 4MHz HARMONIC DISTORTION vs  
OUTPUT SWING  
20  
PAR = 5.4  
14.5dBm ON LINE  
10  
THD  
0
-10  
-20  
-30  
-40  
-50  
-60  
-70  
-80  
FIGURE 45 CIRCUIT  
-64dBc  
2nd HD  
3rd HD  
7.995M  
8.000M  
8.005M  
FREQUENCY (Hz)  
FIGURE 6. 4MHz HARMONIC DISTORTION vs LOAD  
FIGURE 5. 17MHz DMT PROFILE  
FN6916.0  
September 23, 2009  
7
ISL1539A  
Typical Performance Curves  
V
= ±12V, R = 3.2kΩ, G = 10V/V (differential), R  
LOAD  
= 100Ω, T +25°C, C0 = 3.3V, C1 = I  
= 0V  
ADJ  
CC  
F
D
A
(medium power), unless otherwise noted.  
9
V
= 0.5V  
O
P-P  
2V  
P-P  
6
3
AV = 10, R = 3.2kΩ  
5V  
P-P  
F
AV = 20, R = 2.8kΩ  
F
A
= 10  
V
0.5V  
P-P  
10V  
AV = 40, R = 2.4kΩ  
P-P  
F
0
20V  
P-P  
-3  
-6  
-9  
-12  
A
= 40  
V
A
= 20  
V
1M  
10M  
100M  
1G  
FREQUENCY (Hz)  
FIGURE 8. LARGE SIGNAL FREQUENCY RESPONSE  
FIGURE 7. SMALL SIGNAL FREQUENCY RESPONSE vs  
GAIN  
3rd HD  
2nd HD  
3rd HD  
2nd HD  
THD  
THD  
FIGURE 10. 4MHz HARMONIC DISTORTION vs  
OUTPUT SWING  
FIGURE 9. 1MHz HARMONIC DISTORTION vs  
OUTPUT SWING  
20  
PAR = 5.4  
19dBm ON LINE  
FIGURE 45 CIRCUIT  
0
-20  
-65dBc  
-40  
-60  
2nd HD  
3rd HD  
THD  
-80  
-100  
8.395M  
8.400M  
8.405M  
FREQUENCY (Hz)  
FIGURE 12. 4MHz HARMONIC DISTORTION vs LOAD  
FIGURE 11. VDSL2+ 8MHz DMT PROFILE  
FN6916.0  
September 23, 2009  
8
ISL1539A  
Typical Performance Curves  
V
= ±12V, R = 3.2kΩ, G = 10V/V (differential), R  
LOAD  
= 100Ω, T +25°C, C1 = 3.3V, C0 = I  
ADJ  
= 0V (low  
CC  
F
D
A
power), unless otherwise noted.  
9
V
= 0.5V  
O
P-P  
6
3
AV = 10, R = 3.2kΩ  
F
AV = 20, R = 2.8kΩ  
F
0.5V  
P-P  
A
= 10  
V
AV = 40, R = 2.4kΩ  
10V  
P-P  
F
2V  
P-P  
0
-3  
-6  
-9  
-12  
20V  
P-P  
5V  
A
= 40  
V
P-P  
A
= 20  
V
1M  
10M  
100M  
1G  
FREQUENCY (Hz)  
FIGURE 13. SMALL SIGNAL FREQUENCY RESPONSE  
vs GAIN  
FIGURE 14. LARGE SIGNAL FREQUENCY RESPONSE  
THD  
THD  
3rd HD  
2nd HD  
2nd HD  
3rd HD  
FIGURE 15. 1MHz HARMONIC DISTORTION vs  
OUTPUT SWING  
FIGURE 16. 4MHz HARMONIC DISTORTION vs  
OUTPUT SWING  
20  
PAR = 5.4  
19dBm ON LINE  
FIGURE 45 CIRCUIT  
THD  
0
-20  
-60dBc  
-40  
2nd HD  
3rd HD  
-60  
-80  
-100  
1.995M  
2.000M  
2.005M  
FREQUENCY (Hz)  
FIGURE 18. 4MHz HARMONIC DISTORTION vs LOAD  
FIGURE 17. ADSL2+ DMT  
FN6916.0  
September 23, 2009  
9
ISL1539A  
Typical Performance Curves  
V
= ±12V, R = 3.2kΩ, G = 10V/V (differential), R  
LOAD  
= 100Ω, T +25°C, C0 = C1= I  
= 0V (full power),  
CC  
F
D
A
ADJ  
unless otherwise noted.  
2.2kΩ  
22pF  
2.6kΩ  
15pF  
3.2kΩ  
3.8kΩ  
4.7pF  
0pF  
4.6kΩ  
FIGURE 19. SMALL SIGNAL FREQUENCY RESPONSE  
vs RF  
FIGURE 20. SMALL SIGNAL FREQUENCY RESPONSE  
vs C  
LOAD  
-40  
-50  
5V  
P-P-DIFF  
THD  
Rs = 26.7Ω  
= 22pF  
Rs = 84.5Ω  
= 4.7pF  
C
L
C
L
-60  
-70  
2nd HD  
-80  
Rs = 50Ω  
C
= 10pF  
L
-90  
Rs = 38.4Ω  
3rd HD  
10M  
C
= 15pF  
L
-100  
100k  
1M  
100M  
FREQUENCY (Hz)  
FIGURE 21. SMALL SIGNAL FREQUENCY RESPONSE  
vs C WITH Rs  
FIGURE 22. DISTORTION vs FREQUENCY  
LOAD  
100  
10  
1
INVERTING CURRENT NOISE  
VOLTAGE NOISE  
NON-INVERTING CURRENT NOISE  
100  
1k  
10k  
100k  
1M  
10M  
FREQUENCY (Hz)  
FIGURE 23. INPUT VOLTAGE AND CURRENT NOISE DENSITY  
FN6916.0  
September 23, 2009  
10  
ISL1539A  
Typical Performance Curves  
V
= ±12V, R = 3.2kΩ, G = 10V/V (differential), R  
LOAD  
= 100Ω, T +25°C, C0 = 3.3V, C1 = I = 0V  
ADJ  
CC  
F
D
A
(medium power), unless otherwise noted.  
2.2kΩ  
22pF  
2.6kΩ  
15pF  
4.7pF  
3.2kΩ  
3.8kΩ  
0pF  
4.6kΩ  
FIGURE 24. SMALL SIGNAL FREQUENCY RESPONSE  
vs RF  
FIGURE 25. SMALL SIGNAL FREQUENCY RESPONSE  
vs C  
LOAD  
-40  
-50  
5V  
P-P-DIFF  
Rs = 26.7Ω  
CL = 22pF  
THD  
Rs = 84.5Ω  
-60  
CL = 4.7pF  
-70  
Rs = 50Ω  
CL = 10pF  
-80  
2nd HD  
-90  
Rs = 38.4Ω  
3rd HD  
CL = 15pF  
-100  
100k  
1M  
10M  
100M  
FREQUENCY (Hz)  
FIGURE 26. SMALL SIGNAL FREQUENCY RESPONSE  
vs CLOAD WITH Rs  
FIGURE 27. DISTORTION vs FREQUENCY  
100  
INVERTING CURRENT NOISE  
10  
VOLTAGE NOISE  
NON-INVERTING CURRENT NOISE  
1
100  
1k  
10k  
FREQUENCY (Hz)  
FIGURE 28. INPUT VOLTAGE AND CURRENT NOISE DENSITY  
100k  
1M  
10M  
FN6916.0  
September 23, 2009  
11  
ISL1539A  
Typical Performance Curves  
V
= ±12V, R = 3.2kΩ, G = 10V/V (differential), R  
LOAD  
= 100Ω, T +25°C, C1= 3.3V, C0 = I  
= 0V (low  
CC  
F
D
A
ADJ  
power), unless otherwise noted.  
22pF  
2.2kΩ  
2.6kΩ  
15pF  
3.2kΩ  
0pF  
3.8kΩ  
4.7pF  
4.6kΩ  
FIGURE 29. SMALL SIGNAL FREQUENCY RESPONSE  
vs RF  
FIGURE 30. SMALL SIGNAL FREQUENCY RESPONSE  
vs CLOAD  
-40  
5V  
P-P-DIFF  
-50  
-60  
Rs = 26.7Ω  
CL = 22pF  
Rs = 84.5Ω  
CL = 4.7pF  
THD  
-70  
Rs = 38.4Ω  
CL = 15pF  
2nd HD  
Rs = 50Ω  
CL = 10pF  
-80  
-90  
3rd HD  
-100  
100k  
1M  
10M  
100M  
FREQUENCY (Hz)  
FIGURE 32. DISTORTION vs FREQUENCY  
FIGURE 31. SMALL SIGNAL FREQUENCY RESPONSE  
vs CLOAD WITH Rs  
100  
INVERTING CURRENT NOISE  
10  
VOLTAGE NOISE  
NON-INVERTING CURRENT NOISE  
1
100  
1k  
10k  
FREQUENCY (Hz)  
FIGURE 33. INPUT VOLTAGE AND CURRENT NOISE DENSITY  
100k  
1M  
10M  
FN6916.0  
September 23, 2009  
12  
ISL1539A  
Typical Performance Curves  
V
= ±12V, R = 3.2kΩ, G = 10V/V (differential), R = 100Ω, T +25°C, C0 and C1 Parametric, unless  
LOAD A  
CC  
F
D
otherwise noted.  
-20  
-30  
-40  
-50  
-60  
-70  
-80  
-90  
-100  
OUTPUT -> OUTPUT REFERRED  
FULL POWER  
PortCD=>PortAB  
MEDIUM POWER  
LOW POWER  
PortAB=>PortCD  
100k  
1M  
10M  
FREQUENCY (Hz)  
100M  
FIGURE 35. CHANNEL TO CHANNEL X-TALK  
FIGURE 34. COMMON MODE SMALL SIGNAL  
FREQUENCY RESPONSE  
-20  
26  
23  
20  
INPUT REFERRED  
-30  
-40  
±12V  
-50  
17  
-60  
±10V  
-70  
14  
±7.5  
-PSRR  
-80  
11  
8
-90  
-100  
-110  
-120  
+PSRR  
5
2
100k  
1M  
10M  
100M  
1M  
10M  
100M  
1G  
FREQUENCY (Hz)  
FREQUENCY (Hz)  
FIGURE 36. SMALL SIGNAL BANDWIDTH vs SUPPLY  
VOLTAGE  
FIGURE 37. +PSRR TO DIFFERENTIAL OUTPUT  
1 PORT  
FULL POWER  
MEDIUM LOW POWER  
NEGATIVE  
LOW POWER  
POSITIVE  
FIGURE 38. SUPPLY CURRENT vs R  
ADJ  
FN6916.0  
September 23, 2009  
13  
ISL1539A  
Typical Performance Curves  
V
= ±12V, R = 3.2kΩ, G = 10V/V (differential), R  
LOAD  
= 100Ω, T +25°C, I  
= 0V, C0, C1 varied, unless  
CC  
F
D
A
ADJ  
otherwise noted.  
C0, C1  
1V/Div  
1V/Div  
C0, C1  
VOUT  
VOUT  
2V/Div  
2V/Div  
40ns/DIV  
2µs/DIV  
FIGURE 39. POWER-UP TIME  
FIGURE 40. POWER-DOWN TIME  
JEDEC JESD51-7 HIGH EFFECTIVE THERMAL  
CONDUCTIVITY TEST BOARD  
EXPOSED DIEPAD SOLDER TO PCB PER JESD51-5  
0
-20  
4.0  
3.5  
3.0  
2.5  
2.0  
1.5  
1.0  
0.5  
0
HTSSOP24 = +36°C/W  
QFN24 = +39°C/W  
-40  
-60  
-80  
-100  
-120  
85  
1M  
10M  
100M  
0
25  
50  
75  
100  
125  
150  
FREQUENCY (Hz)  
AMBIENT TEMPERATURE (°C)  
FIGURE 41. OFF-ISOLATION  
FIGURE 42. PACKAGE POWER DISSIPATION vs  
AMBIENT TEMPERATURE  
FN6916.0  
September 23, 2009  
14  
ISL1539A  
Test Circuit  
A
R
NETWORK  
ANALYZER  
+12  
DC  
SPLITTER  
S
50Ω  
50Ω  
LOAD  
1:1  
487Ω  
53Ω  
DUT  
180°  
SPLITTER  
R
L
487Ω  
50Ω  
-12  
FIGURE 43. FREQUENCY RESPONSE CHARACTERIZATION CIRCUIT  
FN6916.0  
September 23, 2009  
15  
ISL1539A  
power for Channels A and B together and then the other  
pair controls Channels C and D together.  
Applications Information  
Applying Wideband Current Feedback Op  
Amps as Differential Drivers  
Very low output distortion at low power can be provided  
by the differential configuration. The high slew rate  
intrinsic to the CFA topology also contributes to the  
exceptional performance shown in Figures 22, 27 and 32.  
These swept frequency distortion plots show extremely  
low distortion at 200kHz holding to very low levels up  
through 20MHz. At the lowest operating power  
A current feedback amplifier (CFA) like the ISL1539A is  
particularly suited to the requirements of high output  
power, high full power bandwidth, differential drivers.  
This topology offers a very high slew rate on low  
quiescent power and the ability to hold relatively  
constant AC characteristics over a wide range of gains.  
The AC characteristics are principally set by the feedback  
resistor value in simple differential gain circuits as shown  
in Figure 44.  
(Figure 32, which is at low power, or 6.75mA per  
amplifier or 13.5mA/port) we still see < -70dBc through  
5MHz for a 5V  
differential output swing.  
P-P  
Advanced Configurations - Active  
Termination  
+12V  
Where the best power efficiency is required in a full  
duplex DSL line interface application, it is common to  
apply the circuit shown below to reduce the power loss in  
the matching element while retaining a higher  
impedance for the upstream signal coming into this  
output stage. This circuit acts to provide a higher  
apparent output impedance (through its cross-coupled  
positive feedback through the Rp resistors) while  
physically taking a smaller IR drop through the Rm  
resistors for the output signal..  
+
¼
Ro  
Rb  
ISL1539A  
-
Rf  
1:n  
3.2k  
VI  
VO  
Rg711  
Rf  
LOAD  
SOURCE  
3.2k  
-
¼
ISL1539A  
+
+12V  
Ro  
1 PORT OF 2  
DRAWN  
I = 13.5mA  
AV-DIFF = VO/VI = 10V/V  
+
Rb  
50Ω  
-12V  
¼
ISL1539A  
0V  
C0  
TYPICAL DIFFERENTIAL I/O LINE DRIVER  
(1 OF 2 PORTS)  
3.3V  
-
C1  
FIGURE 44. PASSIVE TERMINATION CIRCUIT  
Rf  
Rp  
Rp  
Rf  
Rm  
RL  
Vdiff  
POWER  
SPLITTER  
In this differential gain of 10 V/V circuit, the 3.2k  
feedback resistors are setting the bandwidth while the  
711 gain resistor controls the gain. The Vo/Vi gain for  
this circuit is set by Equation 1:  
Vi  
Rg  
Ω
82.6  
Vo  
Rm  
2
Ω
RL = 100 /(1.1) = 82.6  
Vo/Vdiff = 9.77 V/V (19.8dB)  
-
Rf  
Rg  
Vo  
Vi  
3.2kΩ  
711Ω  
¼
(EQ. 1)  
=1+ 2  
=1+ 2  
=10  
ISL1539A  
Radj  
+
Ω
0
Ω
50  
The effect of increasing or decreasing the feedback  
-12V  
resistor value is shown in Figures 19, 24 and 29 (at the 3  
power settings). Increasing R will tend to roll off the  
response while decreasing it will peak the frequency  
F
FIGURE 45. ACTIVE TERMINATION TEST CIRCUIT  
response up extending the bandwidth. R was adjusted  
G
This circuit is showing one of two ports configured in an  
active termination circuit used for some of the  
specification and characterization tests. This is showing  
the device operating in the low power mode, but data  
has been shown at the other power settings as well.  
in each of these plots to hold a constant gain of 10 (or  
20dB). This shows the flexibility offered by the CFA  
topology - the frequency response can be controlled with  
the value of the feedback resistor with the R resistor  
G
then setting the desired gain.  
The 82.6Ω differential load is intended to emulate a 100Ω  
The ISL1539A provides 4 very power efficient, high  
output current, CFA's. These are intended to be  
connected as two pairs of differential drivers. The pinout  
diagrams of page two show that Channels A and B are  
intended to operate as a pair while Channels C and D  
comprise the other pair. Power control is also provided  
through two pairs of control pins which separately set the  
line load reflected through a 1:1.1 turns ratio  
2
transformer (100Ω/(1.1 ) = 82.6Ω load). The gain and  
output impedance for this circuit can be described by the  
following equations.  
The ideal transfer function is set by the open circuit gain  
(RL = infinite) and an equivalent output impedance Z .  
O
FN6916.0  
September 23, 2009  
16  
ISL1539A  
produce a 40V  
P-P  
differential swing which will drop to the  
load divided by 1.36 - or a 29.41V differential swing.  
Vo  
Vi  
RL  
P-P  
(EQ. 2)  
= Aoc  
Distortion and MTPR  
RL + Zo  
The ISL1539A is intended to provide very low distortion  
levels under the demanding conditions required by the  
discrete multi-tone (DMT) characteristic of modern DSL  
modulations. The standard test for linearity is the Multi-  
Tone Power Ratio (MTPR) test where a specified standard  
is loaded up with discrete carriers over the specified  
frequencies in such a way as to produce the maximum  
rated line power and Peak to Average Ratio (PAR) with  
some tones missing. The measure of linearity is the  
separation from the active tones vs. a missing tone. To  
the extent that the amplifier is slightly non-linear, it will  
fold a small amount of power into the missing tones  
through intermodulation products for the active tones.  
Figure 17 shows the circuit operating at the low power  
setting used to test ADSL2+ frequency plan and power.  
For this test the carriers are spaced at 5kHz.  
The goal of the positive feedback resistor, R , is to  
provide some “gain” in the apparent output impedance  
over just the 2*R . It also will act to increase the A  
over the simple differential gain equation if a synthesis  
factor (SF) is defined as shown in Equation 3:  
P
M
OC  
1
SF =  
(EQ. 3)  
Rf Rm  
1−  
Rp  
We can see this "gain" is achieved by letting R be > R  
The closer R is to R -R , the more "gain" is achieved  
but at the risk of instability. With this SF defined as  
shown above, the exact A  
Equations 4 and 5:  
P
F
P
F
M
and Z will be as shown in  
OC  
O
This -60dBc MTPR is exceptional for the very low 13.5mA  
total quiescent current used in this configuration.  
Operating at reduced power targets on the line will  
improve MTPR as will operating the amplifiers at higher  
quiescent current.  
Rf Rf Rm  
(EQ. 4)  
Aoc = SF(1+ 2  
+
)
Rg  
Rp  
The characteristic curves show the exceptional single  
tone performance available using the ISL1539A. At the  
highest quiescent power, operating at a simple  
(EQ. 5)  
Zo = SF(2Rm )  
For test purposes, the circuit shown in Figure 45 was  
configured to achieve the following results.  
differential gain of 10V/V, Figure 22 shows the 5V  
distortion plot.  
P-P  
SF = 2.19  
Figure 22 shows a better than -80dBc through 8MHz for  
the 2nd and 3rd harmonics. The rapid rise in the spurious  
above 10MHz is coming from the onset of fine scale slew  
limiting effects. By 20MHz, the output signal is requiring  
a differential slew rate of 300V/µs - a significant portion  
of the available 3000V/µs slew rate available at full  
power.  
A
= 17.7V/V  
OC  
Z = 66Ω  
O
Putting these together into the gain to an 82.6Ω load  
gives the following test condition as shown by  
Equation 6.  
Vo  
Vi  
RL  
82.6Ω  
82.6Ω + 66Ω  
V
⎛ ⎞  
Power Control Function  
= Aoc  
=17.7  
= 9.84  
⎜ ⎟  
RL + Zo  
V
⎝ ⎠  
Figure 46 shows a simplified schematic for the power  
control features included in the ISL1539A. Each of the 4  
differential pairs shown in the drawing are used to steer  
(EQ. 6)  
The advantage offered by this technique is that for  
whatever swing we desire at the load, there is less rise  
through the physical output matching resistor than if we  
simply inserted two 33Ω R resistors to achieve the 66Ω  
output impedance achieved in this test circuit. Whatever  
load current is required in R will rise to the output pins  
through 2*R . The rise from the load swing to the output  
pin swing is given by Equation 7:  
control currents (I  
mirrors (not shown) that control the quiescent bias  
terms) into additional current  
BIAS  
current for each of the two ports. This bias control shares  
M
the I  
pin. When I is grounded, the typical supply  
ADJ  
ADJ  
current levels shown in the “Electrical Specifications”  
tables on page 5 are produced. Inserting an external  
L
M
resistor to ground in the I  
currents down, as shown in Figure 38.  
pin will scale the quiescent  
ADJ  
RL + 2Rm  
It is also possible to scale the I currents up by tying  
the I  
ADJ  
long as the resulting voltage divider between this  
external negative voltage and the internal +0.4V on the  
other side of the 500Ω resistor stays above the  
ADJ  
pin through a resistor to a negative supply. As  
(EQ. 7)  
RL  
This was only 1.36 for the test circuit shown above. In  
differential circuits the ±V at the output pins produces a  
P
maximum rated negative voltage on the I  
pin (-1V).  
ADJ  
4V for the differential peak-to-peak voltage. Hence a  
P
For instance, to double the typical quiescent current  
levels, the current in the I pin must be doubled from  
±10V swing at each output in the above circuit will  
ADJ  
its nominal 800µA level. Using a -5V supply through an  
FN6916.0  
September 23, 2009  
17  
ISL1539A  
external 2.88kΩ resistor will double the current while  
leaving the I pin voltage at approximately -0.4V,  
with the output to isolate the phase margin effects of the  
capacitor. Figure 20 on page 10 shows the effect of  
capacitive load on the differential gain of 10 circuit. With  
15pF on each output, we see about 5dB peaking. This will  
ADJ  
which is well within rated minimum. This approach  
should be used with great caution as very high internal  
power dissipations can easily be produced. However, it  
can be a useful approach to extend operation,  
particularly when operating on lower total supply  
voltages than the rated typical of ±12V.  
increase quickly at higher C  
peaking is unacceptable, a small series resistor can be  
. If this degree of  
loads  
used to improve the flatness as shown in Figure 21.  
Output DC Error Model  
+VCC  
+VCC  
+VCC  
+VCC  
IBIAS IBIAS  
IBIAS IBIAS  
Often, non-inverting bias current (ibn), inverting bias  
current (ibi), and input offset voltage (Vio) are quite low  
for typical op amps.  
+3.3V  
50k  
+3.3V  
+3.3V  
+3.3V  
50k  
50k 50k  
Vio, ibn, ibi can be mapped to output offset both  
common and differential mode. Consider the circuit in  
Figure 47.  
+1.4  
V
+1.4V  
COAB  
C1CD  
C1AB  
COCD  
+1V  
+Vcc  
± Vio  
500  
RO  
+
IADJ  
±ibn  
FIGURE 46. BIAS CONTROL CIRCUIT  
Rb  
-
The current in RO divides in 1/4 levels to form the bias  
current for the 4 pairs of differential switches. Each pair  
of switches controls the quiescent current for one port.  
Rf  
Vcm ± Vocm ± Vodm  
±ibi  
±ibi  
Vcm  
Rcm  
Zg  
For instance, C0 and C1  
control the quiescent  
AB AB  
+Vcc  
current for the port constructed from amplifiers A and B.  
If both control lines are unconnected externally, the  
internal 50kΩ pull-up will switch the differential pairs to  
divert the 100µA tail currents into the supply turning off  
the amplifiers. Taking both control pins low will pass both  
Rf  
-
Rb  
±Vio  
+
I
lines on into scaling current sources. With I  
BIAS  
grounded, this will give the typical 27.2mA total  
REF  
± ibn  
quiescent current for a port shown in the “Electrical  
Specification” tables on page 5. Taking C high (>2V)  
FIGURE 47. DC ERROR MODEL  
0
while leaving C low (<0.8V) will reduce the current into  
1
The output common mode offset voltage (Vo-cm) is  
derived from the input common mode voltage (Vi-cm),  
as expressed in Equations 8 and 9:  
a port to a typical 23mA. Taking C high, while leaving C  
1
0
low will reduce the current in a port to a typical 13.5mA  
supply current. Table 2 summarizes the operation modes  
for ISL1539A for each port.  
(EQ. 8)  
Vicm = ±2 × ibn × Rcm ± ibn × Rb ± Vio  
TABLE 2. POWER MODES OF THE ISL1539A  
(EQ. 9)  
Vocm = ± Vicm ± Rf × ibi  
C
C
OPERATION  
I Full Power Mode  
1
0
0
0
1
1
0
1
0
1
S
The output differential mode offset voltage (Vo-dm) is  
derived from the input differential mode voltage (Vi-dm),  
as expressed in Equations 10 and 11:  
I Medium Power Mode  
S
I Low Power Mode  
S
Vidm = ±Δibn × Rb ± ΔVio  
(EQ. 10)  
Power-Down  
2Rf  
Rg  
---------  
Vodm = ±Vidm × 1 +  
± Δibi × Rf  
Performance Considerations  
(EQ. 11)  
Driving Capacitive Loads  
Example:  
All closed loop op amps are susceptible to reduced phase  
margin when driving capacitive loads. This shows up as  
peaking in the frequency response that can, in extreme  
situations, lead to oscillations. The ISL1539A is designed  
to operate successfully with small capacitive loads such  
as layout parasitics. As the parasitic capacitance  
Referring to the “Electrical Specification” tables on  
page 6:  
ibn = 8µA, Δibn = 2µA  
ibi = 75µA, Δibi = 35µA  
Vio = 8mV, ΔVio = 2mV  
increases, it is best consider a small resistor in series  
FN6916.0  
September 23, 2009  
18  
ISL1539A  
Assuming Rf = 3kΩ, Rg = 333Ω, Rb = 7.5kΩ Rcm = 5kΩ,  
the total output offset voltage derived is expressed in  
Equation 12:  
+VS  
-
+
(EQ. 12)  
Vcm = Vocm + 0.5 × Vodm = 434mV  
Given the worst case DC errors, 434mV of DC shift will  
be at the output reducing the available output swing  
slightly. Actual operation should never see this much  
shift as the error terms are not completely  
independent.  
RL  
VP  
-
+
-VS  
Output Headroom Model  
FIGURE 49. HEADROOM MODEL  
Driving high voltages into heavy loads will require a  
careful consideration of the available output swing vs.  
load. Figure 48 shows a useful model for predicting the  
available output swing. If the output is modeled as ideal  
NPN and PNP transistors, the output swing limits can be  
described as no load headrooms (V and V ) and an  
For equal bipolar supplies, the available peak output  
swing will be given by Equation 13:  
2(Vs Vp Vn )  
Vp =  
P
N
(EQ. 13)  
Rp + Rn  
equivalent impedance to the supplies (R and R )  
P
N
1+  
RL  
+VS  
For example, to worst case the typical gain of 10 design  
using ±12V supplies with ±5% supply tolerance and a  
RP  
+
minimum expected load of 90Ω, a maximum V can be  
VP  
P
calculated as shown in Equation 14:  
+/-VO  
RL  
2(Vs Vp Vn )  
2(11.4 2.2)  
6.7Ω + 7.4Ω  
Vp =  
=
=15.9Vp  
Rp + Rn  
1+  
1+  
90Ω  
RL  
+
VN  
(EQ. 14)  
RN  
The minimum V  
P-P  
would be twice this, or 31.8V .  
P-P  
-VS  
While this extreme condition would normally not be  
encountered, it does show the importance of knowing  
your minimum expected load for high output swing  
conditions.  
FIGURE 48. HEADROOM MODEL  
The no load headrooms can be found in the “Electrical  
Specifications” table on page 5 as 12V - 10.9V = 1.1V  
and they are equal to each supply.  
Output Noise Model  
The full differential output noise model for the ISL1539A  
should include the 3 input noise terms for each device as  
well as the noise contributions due to the external  
resistors.  
The equivalent impedances for this model can be  
extracted from the reduced swings shown in the  
specification table for the heavier loads. Looking at the  
typical 60Ω load swings, we see a +9.8V and -9.7V  
swing. Solving for the two resistors in the Headroom  
model shown in Figure 48 gives:  
This necessarily becomes an involved model due to the  
number of terms, but if the terms that are the same on  
each side of the differential circuit can be assumed to be  
equal, it will simplify considerably. The noise model  
shown in Figure 50 includes all of the op amp terms and  
resistor terms. This model is directed at calculating the  
differential output spot noise for different values of the  
resistors in the simple differential gain circuit. It is  
assuming each amplifier term is independent and  
uncorrelated to the other terms.  
Rp = 6.7Ω and Rn = 7.4Ω.  
For the differential configuration, Figure 49 shows the  
Headroom model that can be used to predict the  
maximum available swing for a given supply voltage and  
load resistor, R .  
L
FN6916.0  
September 23, 2009  
19  
ISL1539A  
Board Design Recommendations  
RS  
iN  
eN  
+
-
The feedback resistors need to be placed as close as  
possible to the output and inverting input pins to  
minimize parasitic capacitance in the feedback loop. This  
includes the R and R resistors in the active termination  
4kTRS  
RF  
ii  
4kTRF  
4kTRF  
(nV Hz)  
eO  
F
P
4kT  
RG  
RG  
RF  
configuration. Keep the gain resistor also very close to  
the inverting inputs for its port and minimize parasitic  
capacitances to ground or power planes as well.  
ii  
-
+
RS  
iN  
Close placement of the supply decoupling capacitors  
will minimize parasitic inductance in the supply path.  
High frequency load currents are typically pulled  
through these capacitors so close placement of 0.01µF  
capacitors on each of the supply pins will improve  
dynamic performance. Higher valued capacitors, 6.8µF  
typically, can be placed further from the package as  
they are providing more of the low frequency  
decoupling.  
eN  
4kTRS  
FIGURE 50. OUTPUT NOISE MODEL  
In Figure 50, the circle sources are noise voltages while  
the diamonds are noise currents and 4kT is 1.6E - 20J.  
If the op amp terms are assumed to be equal for the two  
sides of the circuit and two R and R resistors are also  
F
S
equal, and the differential gain is defined as  
Ad = 1+2R /R , the differential output noise expression  
The thermal pad for the ISL1539A should be connected  
F
G
to either ground or the -V power plane. The choice of  
becomes Equation 15.  
S
which plane depends on which one would have the  
more accessible thermal area.  
eo = 2  
(
Ad2  
)(  
en2 +  
(
inRs  
)
2 + 4kTRs  
)
+ 2  
(
iiRf  
)
2 + 2Ad  
(
4kTRf  
)
While the ISL1539A is relatively robust in driving  
parasitic capacitive loads, it is always preferred to get  
into any series output resistor needed in the design as  
physically close as possible to the output pins. Then  
trace capacitance on the other side of that resistor will  
have a much smaller effect on loop phase margin.  
(EQ. 15)  
Putting in numbers for the gain of 10 characterization  
circuit (with R = 50Ω) gives a differential output noise of  
e = 69nV/Hz. Dividing this by the differential gain of 10  
S
o
gives an input noise of e = 6.9nV/Hz which is only  
i
slightly more than the RMS sum of the two 4nV input  
voltage noise terms for the op amps themselves  
(5.7nV/Hz).  
Protection devices that are intended to steer large load  
transients away from the ISL1539A output stage and  
into the power supplies or ground should have a short  
trace from their supply connections into the nearest  
supply capacitor - or should include their own supply  
capacitors to provide a low impedance path under fast  
transient conditions.  
FN6916.0  
September 23, 2009  
20  
ISL1539A  
Revision History  
The revision history provided is for informational purposes only and is believed to be accurate, but not warranted. Please go to  
web to make sure you have the latest Rev.  
DATE  
REVISION  
CHANGE  
9/23/09  
FN6916.0  
Initial Release.  
Products  
Intersil Corporation is a leader in the design and manufacture of high-performance analog semiconductors. The  
Company's products address some of the industry's fastest growing markets, such as, flat panel displays, cell phones,  
handheld products, and notebooks. Intersil's product families address power management and analog signal  
processing functions. Go to www.intersil.com/products for a complete list of Intersil product families.  
*For a complete listing of Applications, Related Documentation and Related Parts, please see the respective device  
information page on intersil.com: ISL1539A  
To report errors or suggestions for this datasheet, please go to www.intersil.com/askourstaff  
FITs are available from our website at http://rel.intersil.com/reports/search.php  
FN6916.0  
September 23, 2009  
21  
ISL1539A  
Package Outline Drawing  
L24.4x5B  
24 LEAD QUAD FLAT NO-LEAD PLASTIC PACKAGE  
Rev 0, 10/06  
4.00  
2.50  
A
PIN 1  
PIN #1 INDEX AREA  
24X0.40  
INDEX AREA  
CHAMFER 0.40×0 X 45°  
B
20  
24  
6
6
1
19  
3.50  
0.5x6=3.00 REF  
7
13  
12  
8
0.10  
0.25±0.05  
0.10  
4X  
0.50  
M
C A B  
TOP VIEW  
0.5x4=2.00 REF  
BOTTOM VIEW  
SEE DETAIL X''  
0.10  
C
C
SEATING PLANE  
0.08  
0.90±0.10  
C
(24x0.25)  
(20x0.50)  
SIDE VIEW  
(3.50)  
(4.80 TYP)  
5
0 . 20 REF  
C
(24x0.60)  
(2.50)  
(3.80 TYP)  
0 . 00 MIN.  
0 . 05 MAX.  
TYPICAL RECOMMENDED LAND PATTERN  
DETAIL "X"  
NOTES:  
1. Dimensions are in millimeters.  
Dimensions in ( ) for Reference Only.  
2. Dimensioning and tolerancing conform to AMSE Y14.5m-1994.  
3. Unless otherwise specified, tolerance : Decimal ± 0.05  
4. Dimension b applies to the metallized terminal and is measured  
between 0.20mm and 0.30mm from the terminal tip.  
5. Tiebar shown (if present) is a non-functional feature.  
6. The configuration of the pin #1 identifier is optional, but must be  
located within the zone indicated. The pin #1 indentifier may be  
either a mold or mark feature.  
FN6916.0  
September 23, 2009  
22  
ISL1539A  
HTSSOP (Heat-Sink TSSOP) Family  
0.25 M C A B  
MDP0048  
D
A
HTSSOP (HEAT-SINK TSSOP) FAMILY  
(N/2)+1  
N
MILLIMETERS  
TOLER-  
ANCE  
SYMBOL 14 LD 20 LD 24 LD 28 LD 38 LD  
PIN #1 I.D.  
A
A1  
A2  
b
1.20  
1.20  
1.20  
1.20  
1.20  
Max  
±0.075  
E
E1  
0.075 0.075 0.075 0.075 0.075  
0.90  
0.25  
0.15  
5.00  
3.2  
0.90  
0.25  
0.15  
6.50  
4.2  
0.90  
0.25  
0.15  
7.80  
4.3  
0.90  
0.25  
0.15  
9.70  
5.0  
0.90  
0.22  
0.15  
9.70  
7.25  
6.40  
4.40  
3.0  
+0.15/-0.10  
+0.05/-0.06  
+0.05/-0.06  
±0.10  
0.20 C B A  
2X  
1
(N/2)  
N/2 LEAD TIPS  
c
TOP VIEW  
B
D
D1  
E
Reference  
Basic  
D1  
EXPOSED  
THERMAL PAD  
6.40  
4.40  
3.0  
6.40  
4.40  
3.0  
6.40  
4.40  
3.0  
6.40  
4.40  
3.0  
E1  
E2  
e
±0.10  
Reference  
Basic  
0.65  
0.60  
1.00  
14  
0.65  
0.60  
1.00  
20  
0.65  
0.60  
1.00  
24  
0.65  
0.60  
1.00  
28  
0.50  
0.60  
1.00  
38  
E2  
L
±0.15  
L1  
N
Reference  
Reference  
Rev. 3 2/07  
BOTTOM VIEW  
NOTES:  
1. Dimension “D” does not include mold flash, protrusions or gate burrs.  
Mold flash, protrusions or gate burrs shall not exceed 0.15mm per  
side.  
0.05  
H
e
C
2. Dimension “E1” does not include interlead flash or protrusions. Inter-  
lead flash and protrusions shall not exceed 0.25mm per side.  
SEATING  
PLANE  
3. Dimensions “D” and “E1” are measured at Datum Plane H.  
0.10 M C A B  
b
4. Dimensioning and tolerancing per ASME Y14.5M-1994.  
0.10 C  
N LEADS  
SIDE VIEW  
SEE DETAIL ‚Äö  
c
END VIEW  
L1  
A2  
A
GAUGE  
PLANE  
0.25  
L
A1  
0¬¨¬®¬¨  
DETAIL X  
For additional products, see www.intersil.com/product_tree  
Intersil products are manufactured, assembled and tested utilizing ISO9000 quality systems as noted  
in the quality certifications found at www.intersil.com/design/quality  
Intersil products are sold by description only. Intersil Corporation reserves the right to make changes in circuit design, software and/or specifications  
at any time without notice. Accordingly, the reader is cautioned to verify that data sheets are current before placing orders. Information furnished by  
Intersil is believed to be accurate and reliable. However, no responsibility is assumed by Intersil or its subsidiaries for its use; nor for any  
infringements of patents or other rights of third parties which may result from its use. No license is granted by implication or otherwise under any  
patent or patent rights of Intersil or its subsidiaries.  
For information regarding Intersil Corporation and its products, see www.intersil.com  
FN6916.0  
September 23, 2009  
23  

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