Cirrus Logic CRD5378 - Manual (Page 27)

CRD5378
DS639RD2 27
2.3.5 External Connector
Power supplies and telemetry signals route to J26, a 20-pin double row connector with 0.1" spacing. This
header provides a compact standardized connection to the CRD5378 external signals.
2.4 Power Supplies
Power is supplied to CRD5378 through the +3.3 V and -3.3 V voltage inputs on the external connector
(J26), which are typically from an external AC-DC or DC-DC converter. Digital circuitry on CRD5378 is
driven directly from the +3.3 V input, while on-board linear regulators create +2.5 V and - 2.5 V analog
power supplies from +3.3 V and -3.3 V.
The +3.3 V and -3.3 V power supply inputs have zener protection diodes that limit the maximum input volt-
ages to +5 V or -5 V with respect to ground. Each input also has 68 uF bulk capacitance for bypassing
and to help settle transients and another 0.01 uF capacitor to bypass high frequency noise.
2.4.1 Analog Voltage Regulators
Linear voltage regulators create the positive and negative analog power supply voltages to the analog
components on CRD5378. These regulate the +3.3 V and -3.3 V power supply inputs to create the +2.5 V
and -2.5 V analog power supplies.
Pins Name Signal
1, 2 CLK+, CLK- Clock Input
3, 4 SYNC+, SYNC- Synchronization Input
5, 6 SCL+, SCL- I2C Clock
7, 8 SDA+, SDA- I2C Data
9, 10 BYP_SDA+, BYP_SDA- I2C Data Bypass
11, 12 BYP_SCL+, BYP_SCL- I2C Clock Bypass
13, 14 TX, GND UART transmit
15, 16 RX, GND UART receive
17, 18 -3.3V, GND Negative Power Supply
19, 20 +3.3V, GND Positive Power Supply
Specification Value
Positive Analog Power Supply
+2.5 V
Low Noise Micropower Regulator - Linear Tech LT1962ES8-2.5
Surface Mount Package Type MSOP-8
Load Regulation, -40 C to +85 C +/- 25 mV
Quiescent Current, Current @ 100 mA Load 30
µA, 2 mA
Output Voltage Noise, 10 Hz - 100 kHz 20
µV
RMS
Ripple Rejection, DC - 200 Hz > 60 dB