User guide

CM52 Integrators’ Manual
CM52 Integrators’ Manual
WI_DEV_CM52_UGD_001-001
Page 22 of 53
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The following table summarizes the power supply requirements from the application.
Max. Current
(Amps)
Max. Ripple (mVpp) Input Supply Voltage
(Volts DC)
Operation 0- 4KHz 4 KHz-
10MHz
VCC_MAIN 5.00 ± 10% 1.4 100mVpp 50mVpp
VCC_AUX 13.8 ± 20% 1.3 600mVpp 240mVpp
VRTC(no GPS) 1.8 to 3.9 1.2 uA
VRTC(with GPS) 3.4 to 3.9 500 uA
Table 6: CM52 Power Supply Requirements
2.4.1 Power Supply Input Capacitance
It should be noted that when applying power to the Wireless CPU
®
, the current will exceed the
maximum input current specified in
Table 6: CM52 Power Supply Requirements, or any other CM52
electrical specification due to the transient current required to charge the de-coupling capacitors
of the Wireless CPU
®
(specified below as C
IN
). The magnitude and duration of the transient current
spike is solely dependent on the application power supply design. Any built-in short circuit
protection in the application power supply must take this in to account as well as all other "Power
Supply" specifications.
The maximum total input capacitance on VCC_MAIN is 100uF. However at “Contact”, 60uF will be
charged instantly by the application’s power supply. Then at “Wake” an additional 14.5uF will be
instantly charged. At that point internal regulators are activated and limit the charge rate of the
remaining capacitance. If VCC_MAIN and VCC_AUX are tied together (0.6W variants only) then the
input capacitance on VCC_AUX is negligible.
The “Wakeup” condition occurs when the MODULE_PWR_EN_B signal transitions from High to Low.
The “Contact” condition occurs when voltage is first asserted to VCC_MAIN, and or VCC_AUX.
Parameter Contact Wakeup Units
VCC_MAIN Input Capacitance (C
IN
) 60 14.5 uF
VCC_AUX Input Capacitance (C
IN
) 33 10 pF
Table 7: Power Supply Input Capacitance (0.6W variants)
Parameter Contact Wakeup 3W assertion
VCC_MAIN Input Capacitance (C
IN
) 60 uF 14.5 uF n/a
VCC_AUX Input Capacitance (C
IN
) 10 uF 10 pF 20 uF
Table 8: Power Supply Input Capacitance (3W variants)