SA58780 Datasheet, PDF (11/15 Pages) NXP Semiconductors – Sense current amplifier with selectable gain

Philips Semiconductors
Sense current amplifier with selectable gain
TYPICAL CHARACTERIZATION CURVES (continued)
V_CC = 5.0 V; V_GSEL = V_ISEL = 5 V; R_L = 10 kΩ; T_amb = 25 °C; unless otherwise specified.
7
6
5
4
3
2
1
0
–250
–150
–50
50
150
INPUT DIFFERENTIAL VOLTAGE, V_IDF (mV)
250
SL02027
Figure 33. Input bias current versus input differential voltage.
Product data
SA58780
APPLICATION INFORMATION
Battery current sensing circuit
The circuit shown in Figure 34 will sense when the load is drawing
current from the battery, and the output of Pin 6 to an
analog-to-digital converter can be used to provide a digital readout.
Pin 8, the Gain Select, is tied to ground. This gives a fixed G_v of
50 V/V. For a fixed G_v of 100 V/V, tie Pin 8 to V_CC. For selectable
gain, Pin 8 may be connected to a user-controlled selector switch or
the output of another device that will change state as the current
rises and falls.
20 MΩ
R_S
1
TO CHARGER CIRCUIT
8
2
3
BATTERY
4
7
TO ADC
6
5
2.5 V
Charger current sensing
The only difference between the battery and charge current sense
circuits is the diode position.
20 MΩ
R_S
1
TO CHARGER CIRCUIT
8
2
3
BATTERY
4
7
TO ADC
6
5
2.5 V
SL01574
Figure 35. Charger current sensing circuit.
SL01573
Figure 34. Battery current sensing circuit.
2003 Nov 10
11