Motorola A860 Service Manual download pdf (Page 19)

June 07, 2004 19

Level 2 Service Manual Theory of Operation

PM6050 Device Description

The PM6050 device (Figure 2) integrates all wireless handset power management,

general housekeeping, and user interface support functions into a single mixed

signal IC. Its versatile design is suitable for CDMA and non-CDMA handsets, as

well as other wireless products such as PC cards, modems, PDAs, etc. The power

management portion accepts power from all the most common sources – battery,

external charger, adapter, coin cell back-up – and generates all the regulated

voltages needed to power the appropriate handset electronics. It monitors and

controls the power sources, detecting which sources are applied, verifying that they

are within acceptable operational limits, and coordinates battery and coin cell

recharging while maintaining the handset electronics supply voltages. Eight

programmable output voltages are generated using low dropout voltage regulators,

all derived from a common trimmed voltage reference.

The device’s general housekeeping functions include a 10-bit ADC whose input is

selected by a 10-position analog multiplexer having five internal and five external

connections. The internal connections are used to monitor voltage sources, charging

status, and current flow. The five external connections are available to monitor

system parameters such as temperature, RF output power, and battery ID. Various

oscillator, clock, and counter circuits are provided to initialize and maintain valid

pulse waveforms and measure time intervals for higher-level handset functions. A

dedicated controller manages the TCXO warm-up and signal buffering, and key

parameters (under-voltage lockout and crystal oscillator signal presence) are mon-

itored to protect against detrimental conditions. Handset-level user interfaces are

also supported. The IC includes four backlight or LED drivers with brightness

(current) control that could be used for the keypad, the LCD, and two user definable

general-purpose drivers. Independent vibrator and ringer/buzzer drivers alert

handset users of incoming calls; these independent drivers can be used simulta-

neously for dual-function applications. A speaker driver with volume control

supports speakerphone and melody-ringer applications. The speaker and ringer/

buzzer drivers share common PM6050 circuitry, so only one can be used at a time.

An MSM device controls and statuses the PM6050 IC using a three-line Serial Bus

Interface (SBI) supplemented by an Interrupt Manager for time-critical informa-

tion. Another dedicated IC interface circuit monitors multiple trigger events and

controls the power-on sequence. The PM6050 is a mixed signal BiCMOS device and

is available in the 56-pad Bump Chip Carrier (56 BCCP) package that includes a

large center slug for electrical ground and thermal relief. Since the PM6050 IC

includes so many diverse functions, its operation is more easily understood by

considering major functional blocks individually. Therefore, the PM6050 document

set is organized according to the following device functionality:

• Input Power Management

• Output Voltage Regulation

• General Housekeeping

• User Interfaces

•IC Interfaces

Most of the information contained in this Device Specification is organized accord-

ingly – including the circuit groupings within the block diagram (Figure 1-1) and

detailed electrical specifications (Section 4). To begin, introductory descriptions of

all the PM6050 device’s circuits are provided in the following subsections.

1 2 ... 14 15 16 17 18 19 20 21 22 23 24 ... 55 56

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