User's Manual

PHS8-US Hardware Interface Overview
3.2 Power Supply
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PHS8-US_HIO_v01.000 Page 21 of 40 2012-01-06
Confidential / Released
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3.2 Power Supply
PHS8-US needs to be connected to a power supply at the SMT application interface - 6 lines
each BATT+ and GND. There are three separate voltage domains for BATT+:
• BATT+_WCDMA with 2 lines for the WCDMA power amplifier supply
• BATT+_GSM with 2 lines for the GSM power amplifier supply
• BATT+ with 2 lines for the general power management.
The main power supply from an external application has to be a single voltage source and has
to be expanded to three sub paths (star structure). Capacitors should be placed as close as
possible to the BATT+ pads. Figure 2 shows two sample circuits (minimum requirement and
recommended alternative) for decoupling capacitors for BATT+.
Figure 2: Decoupling capacitor(s) for BATT+
The power supply of PHS8-US must be able to provide the peak current during the uplink trans-
mission.
All key functions for supplying power to the device are handled by the power management IC.
It provides the following features:
• Stabilizes the supply voltages for the baseband using switching regulators and low drop lin-
ear voltage regulators.
• Switches the module's power voltages for the power-up and -down procedures.
• Delivers, across the VEXT line, a regulated voltage for an external application. This voltage
is not available in Power-down mode and can be reduced via AT command to save power.
• SIM switch to provide SIM power supply.
BATT+
BATT+
BATT+_GSM
BATT+_WCDMA
2
2
2
Decoupling capacitor
e.g. 100…220µF
Ultra-low ESR
Module
GND
SMT interface
+
Minimum requirement
BATT+
2
2
2
Decoupling capacitors
e.g. 47µF X5R MLCC
3x
GND
BATT+
BATT+_GSM
BATT+_WCDMA
Module
SMT interface
Recommended alternative