TABLE 1. SUPERCAP AUTO BALANCING (SAB
™
) MOSFET EQUIVALENT ON RESISTANCE AT
DIFFERENT DRAIN-GATE SOURCE VOLTAGES AND DRAIN-SOURCE ON CURRENTS
Drain-Gate
Gate-
ALD Part
Number
Threshold
Voltage
Vt (V)
ALD910028
2.80
Source
Voltage (V)
2
SAB MOSFET DRAIN-SOURCE ON CURRENT
IDS(ON) (
µ
A)
1
TA = 25
°
C
0.0001
2.4
24000
2.3
23000
2.2
22000
2.1
21000
2.0
20000
1.9
19000
0.001
2.5
2500
2.4
2400
2.3
2300
2.2
2200
2.1
2100
2.0
2000
0.01
2.6
260
2.5
250
2.4
240
2.3
230
2.2
220
2.1
210
0.1
2.7
27
2.6
26
2.5
25
2.4
24
2.3
23
2.2
22
1
2.8
2.8
2.7
2.7
2.6
2.6
2.5
2.5
2.4
2.4
2.3
2.3
10
2.9
0.29
2.8
0.28
2.7
0.27
2.6
0.26
2.5
0.25
2.4
0.24
100
3.02
0.030
2.92
0.029
2.82
0.028
2.72
0.027
2.62
0.026
2.52
0.025
300
3.1
0.01
3.0
0.01
2.9
0.01
2.8
0.01
2.7
0.009
2.6
0.009
1000
3.24
0.003
3.14
0.003
3.04
0.003
2.94
0.003
2.84
0.003
2.74
0.003
3000
3.3
0.001
3.2
0.001
3.1
0.001
3.0
0.001
2.9
0.001
2.8
0.001
10000
3.8
0.0004
3.7
0.0004
3.6
0.0004
3.5
0.0004
3.4
0.0003
3.3
0.0003
Equivalent ON
Resistance (M
Ω
)
VGS = VDS (V)
RDS(ON) (MΩ)
VGS = VDS (V)
RDS(ON) (MΩ)
VGS = VDS (V)
RDS(ON) (MΩ)
ALD910027
2.70
ALD910026
2.60
ALD910025
2.50
VGS = VDS (V)
RDS(ON) (MΩ)
VGS = VDS (V)
RDS(ON) (MΩ)
ALD910024
2.40
ALD910023
2.30
VGS = VDS (V)
RDS(ON) (MΩ)
Drain-Gate
ALD Part
Number
Gate-
Source
Threshold
Voltage (V)
2
Voltage
Equivalent ON
Vt (V)
Resistance (M
Ω
)
2.80
VGS = VDS (V)
RDS(ON) (MΩ)
VGS = VDS (V)
RDS(ON) (MΩ)
VGS = VDS (V)
RDS(ON) (MΩ)
VGS = VDS (V)
RDS(ON) (MΩ)
VGS = VDS (V)
RDS(ON) (MΩ)
VGS = VDS (V)
RDS(ON) (MΩ)
SAB MOSFET DRAIN-SOURCE ON CURRENT
IDS(ON) (
µ
A)
1
TA = 25
°
C
0.0001
2.4
24000
2.3
23000
2.2
22000
2.1
21000
2.0
20000
1.9
19000
0.001
2.5
2500
2.4
2400
2.3
2300
2.2
2200
2.1
2100
2.0
2000
0.01
2.6
260
2.5
250
2.4
240
2.3
230
2.2
220
2.1
210
0.1
2.7
27
2.6
26
2.5
25
2.4
24
2.3
23
2.2
22
1
2.8
2.8
2.7
2.7
2.6
2.6
2.5
2.5
2.4
2.4
2.3
2.3
10
2.9
0.29
2.8
0.28
2.7
0.27
2.6
0.26
2.5
0.25
2.4
0.24
100
3.04
0.030
2.94
0.029
2.84
0.028
2.74
0.027
2.64
0.026
2.54
0.025
300
3.14
0.01
3.04
0.01
2.94
0.01
2.84
0.01
2.74
0.009
2.64
0.009
1000
3.32
0.003
3.22
0.003
3.12
0.003
3.02
0.003
2.92
0.003
2.82
0.003
3000
3.62
0.001
3.52
0.001
3.42
0.001
3.32
0.001
3.22
0.001
3.12
0.001
10000
4.22
0.0004
4.12
0.0004
4.02
0.0004
3.92
0.0004
3.82
0.0004
3.72
0.0004
ALD810028
ALD810027
2.70
ALD810026
2.60
ALD810025
2.50
ALD810024
2.40
ALD810023
2.30
Selection of a SAB MOSFET device depends on a set of desired voltage vs. current characteristics that closely match the selected nominal bias voltage and
bias currents that provide the best leakage and regulation profile of a supercap load. The Vt table, where Drain-Gate Source Voltage (VGS = VDS) gives
a range of VGS = VDS bias voltages as different Vsupercap load voltages. At each VGS = VDS bias voltage, a corresponding Drain-Source ON Current
(IDS(ON)) is produced by a specific SAB MOSFET, which can be viewed as the amount of current available to compensate for supercap leakage current
imbalances and results in an Equivalent ON Resistance (RDS(ON))across a supercap cell. Selection of a supercap bias voltage with a SAB MOSFET
IDS(ON) that corresponds to the maximum supercap leakage current would result in the best possible tradeoff between leakage current balancing and
voltage regulation.
Notes: 1) The SAB MOSFET Drain Source ON Current (IDS(ON)) is the maximum current available to offset the supercapacitor leakage current.
2) The Drain-Gate Source Voltage (VGS=VDS) is normally the same as the voltage across the supercapacitor.
ALD810023, ALD810024, ALD810025,
ALD810026, ALD810027, ALD810028
Advanced Linear Devices, Inc.
5 of 17
ALD [ ADVANCED LINEAR DEVICES ]
