Motorola APX 7000 Detailed Service Manual page 61

Theory of Operation
: Controller
3.2.2.1.2 External Regulators: SW_1.875, SW_1.4, SW_3.6
The controller board contains three TPS62050 regulators in order to regulate voltages of 1.85 V, 1.4
V, and 3.6 V. The TPS62050 is a synchronous step-down adjustable regulator. The switching
regulator is capable of sourcing 800 mA. Its output can be adjusted by using a voltage divider tied to
the feedback pin. The regulators are powered from SW_B+.
VCC_SW_1.4 regulator.
SW_FILT_B+
R6547
0
C6569
10UF
3.2.2.1.3 External Switcher 5
The controller board uses an external TI regulator (TPS62110, U6505) to regulate to 5.4 V. The
TPS62110 is a 1.5 A capable synchronous step down converter. The output is adjusted using a
voltage divider to the feedback pin. The regulator is software enabled through a GPO on MAKO. The
regulator is powered from SW_B+.
Figure 3-26
VCC_1.55
EXTERNAL SWITCHER 1.4V
VCC_SW1.4_VIN
C6570
470PF
DNP
C6572
82PF
R6554
DNP
R6552
0
100K
R6548
270
DNP
R6558
165K
R6555
0
DNP
Figure 3-26. VCC_SW_1.4 Regulator
Figure 3-27
R6533
0
4
EN
10
FB
7
LBI
5
SYNC
2
VIN1
3
VIN2
8
R6537
VINA
121K
R6534
0
C6559
DNP
1UF
R6538
8.2K
Figure 3-27. SW5 Circuit
illustrates the supporting circuitry for the TPS62050.
SW1V4_FB
U6507
TPS62050
8 4
EN
PG
5 9
FB
SW
6 2
LBI
LBO
7
SYNC
illustrates the SW5 circuitry.
C6562 10PF
R6540 475K
6
LBO
14
SW1
15
SW2
13
PG
U6505
TPS62110
Figure 3-26 is the schematic for the
VCC_SW_1.4
C6582
R6568
6.8PF
301K
C6588
L6505
10UH
C6584 C6586
10UF 4.7UF
SWITCHER 5
SW_B+
L6503
180NH
C6565
2.2UF
L6504
10UH
SW5_VOUT_UNFILT
R6545
100K
3-37
C6589
470PF
DNP
82PF
DNP
R6571
270
DNP
VCC_SW_5
C6566 C6567
10UF 10UF