User’s Manual 119A PPENDIX C. POWER S UPPLYAppendix C provides information on the current requirements ofthe RCM4200, and includes some background on the chip selectcircuit used in power management.C.1 Power SuppliesThe RCM4200 requires a regulated 3.0 V – 3.6 V DC power source. The RabbitCoredesign presumes that the voltage regulator is on the user board, and that the power is madeavailable to the RCM4200 board through header J2.An RCM4200 with no loading at the outputs operating at 58.98 MHz typically draws240 mA, and may draw up to 275 mA at 3.6 V and 85°C; the corresponding current drawfor the RCM4210 is typically 200 mA, and up to 225 mA at 3.6 V and 85°C.C.1.1 Battery BackupThe RCM4200 does not have a battery, but there is provision for a customer-supplied bat-tery to back up the data SRAM and keep the internal Rabbit 4000 real-time clock running.Header J2, shown in Figure C-1, allows access to the external battery. This header makesit possible to connect an external 3 V power supply. This allows the SRAM and the inter-nal Rabbit 4000 real-time clock to retain data with the RCM4200 powered down.Figure C-1. External Battery Connectionsat Header J2A lithium battery with a nominal voltage of 3 V and a minimum capacity of 165 mA·h isrecommended. A lithium battery is strongly recommended because of its nearly constantnominal voltage over most of its life." :.(034-4..(0J
