ISL28005_10 Datasheet, PDF (12/14 Pages) Intersil Corporation – Micropower, Rail-to-Rail Input Current Sense Amplifier with Voltage Output

ISL28005
I = 2.86µA
(1mΩ
R_S TO
0.1Ω)
C_M
+ 0.1VDC
TO
- ^28VDC
C_D
R_P
LOAD
R_S+
R_S-
gm_HI
1.35V
gm_LO
V_CC
2.7VDC
TO
28VDC
+
OUT
-
GND
FIGURE 20. TYPICAL APPLICATION CIRCUIT
Overall Accuracy (V_OA %)
V_OA is defined as the total output accuracy
Referred-to-Output (RTO). The output accuracy contains
all offset and gain errors, at a single output voltage.
Equation 2 is used to calculate the % total output
accuracy.
V_OA
=
100
×
⎛
⎜
⎝
V_{-----O----U----T----}a_----cV_---t_-O-u_----Ua_----Tl_{---–-e---xV---p--O--e--U--c--T--t--ee---d-}x_---p_----e_----c_---t_--e_----d_{--⎠⎟⎞}
(EQ. 2)
where:
• P_DMAXTOTAL is the sum of the maximum power
dissipation of each amplifier in the package (PD_MAX)
• PD_MAX for each amplifier can be calculated using
Equation 5:
PD_MAX
=
V_S × I_qMAX + (V_S
-
V_OUTMAX
)
×
V_{-----O----U----T----M-----A----X--}
R_L
(EQ. 5)
where
V_OUT Actual = V_SENSE x GAIN
Example: Gain = 100, For 100mV V_SENSE input we
measure 10.1V. The overall accuracy (V_OA) is 1% as
shown in Equation 3.
V_OA
=
100
×
⎛
⎝
1_----0_---._--11_{----0-–----}1_----0_{-⎠⎞}
=
1percent
(EQ. 3)
Power Dissipation
It is possible to exceed the +150°C maximum junction
temperatures under certain load and power supply
conditions. It is therefore important to calculate the
maximum junction temperature (T_JMAX) for all
applications to determine if power supply voltages, load
conditions, or package type need to be modified to
remain in the safe operating area. These parameters are
related using Equation 4:
T_JMAX = T_MAX + θ_JAxPD_MAXTOTAL
(EQ. 4)
where:
• T_MAX = Maximum ambient temperature
• θ_JA = Thermal resistance of the package
• PD_MAX = Maximum power dissipation of 1 amplifier
• V_CC = Total supply voltage
• I_qMAX = Maximum quiescent supply current of 1
amplifier
• V_OUTMAX = Maximum output voltage swing of the
application
R_L = Load resistance
12
FN6973.3
September 16, 2010