SLUSFU9 October 2024 BQ51013C
PRODUCTION DATA
Refer to the PDF data sheet for device specific package drawings
The BQ51013C device provides two identical, integrated communication FETs which are connected to the pins COMM1 and COMM2. These FETs are used for modulating the secondary load current which allows the BQ51013C to communicate error control and configuration information to the transmitter. Figure 8-10 shows how the COMMx pins can be used for resistive load modulation. Each COMMx pin can handle at most a 24-Ω communication resistor. Therefore, if a COMMx resistor between 12 Ω and 24 Ω is required, COMM1 and COMM2 pins must be connected in parallel. The BQ51013C device does not support a COMMx resistor less than 12 Ω.
In addition to resistive load modulation, the BQ51013C is also capable of capacitive load modulation as shown in Figure 8-11. In this case, a capacitor is connected from COMM1 to AC1 and from COMM2 to AC2. When the COMMx switches are closed there is effectively a 22 nF capacitor connected between AC1 and AC2. Connecting a capacitor in between AC1 and AC2 modulates the impedance seen by the coil, which will be reflected in the primary as a change in current.