UM-B-074
DA1468x Range Extender Daughterboard
User Manual
Revision 1.1
17-Apr-2018
CFR0012
20 of 60
© 2018 Dialog Semiconductor
7.1.3.2
Power Supply
The SKY66112-11 requires three different supply voltages:
●
VCC1:
Supplies the first stage of the PA as well as the LNA.
●
VCC2:
Supplies the second stage of the PA.
●
VDD:
Supplies the logic (switches, bias enable, etc.).
Table 8: SKY66112-11 TX Output Characteristics
Voltage
Rail
FEM
Pin
FEM Specification (V)
Comments
Min
Typ
Max
VCC1
16
1.7
1.8
3.3
VCC1 = 1.8 V, VCC2 = 3.0 V, ICC = 115 mA,
P
OUT
= +21 dBm, P
IN
= -1 dBm
VCC1 = 1.8 V, VCC2 = 3.0 V , ICC = 90 mA,
P
OUT
= +20 dBm, P
IN
= -2 dBm
VCC1 = 1.8 V, VCC2 = 1.8 V , ICC = 60 mA,
P
OUT
= +16 dBm, P
IN
= -3 dBm
VCC1 = 1.8 V, VCC2 = 1.2 V, ICC = 45 mA,
P
OUT
= +13 dBm, P
IN
= -3 dBm
VCC2
14
0.6
3.0
3.3
VDD
11
1.8
3.0
3.3
VDD is supplied by V33 of the DA14680/681.
VCC1 is connected to the V18P voltage rail of DA14680/681. Current consumption and voltage
regulation requirements must be taken under consideration. VCC1 supplies the LNA or the first stage
of the PA with a power consumption of 6 mA or 25 mA (max.) respectively. The V18P output must
present very low ripple and low noise. The V18P power rail has a driving current capability of 75 mA.
The VCC2 voltage level is critical, as it affects the RF PA output level. VCC2 supplies the second
stage of the PA and draws most of the TX current. VCC2 is connected to the V18 power rail
6
. The
VCC2 voltage can be changed using a series resistor R73. The V18 power rail has a current driving
capability of 75 mA.
7.1.4
Transmit (TX) Path
The RF PA TX Power output level is defined primarily by the VCC2 voltage level and secondly by the
control signal settings.
The CPS signal is used to enable the bypass operating mode of the FEM. Enabling CPS provides a
direct path between antenna and DA14680/681 chip.
The CHL functionality is intended to be used to increase efficiency at the lower output power levels
by reducing the PA bias. It is not intended for power control. However at constant VCC2, toggling
CHL will increase/decrease P
OUT
by 0.5 dB to 0.75 dB.
The TX power output is determined based on:
●
VCC2 level which is connected to V18 via a series resistor R73.
●
DA14680/681 TX power set using RF_TX_PWR_REG (0x500020C0). This register can be
programmed from 0 to 4 (0 dBm to -4 dBm).
●
Resistive attenuator populated before or after the PA (optional).
6
This configuration differs from the DA1468x development kit. GPIOs configured to operate at 1.8 V are supplied from the
V18P rail while the ones configured to operate at 3.3 V are supplied from the V33 rail. This means that V18P could only be
used for VCC2 if there are no GPIOs configured to operate at 1.8 V. Therefore, instead of V18P the V18 power rail is used to
supply VCC2.
