UCD3138A datasheet(49/83 Pages) TI

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UCD3138A

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SLUSC66B – MARCH 2015 – REVISED MAY 2015

6.10.4.2 16-Bit PWM Timers

There are four 16 bit counter PWM timers which run off the Interface Clock and can further be divided

down by a 8-bit pre-scaler to generate slower PWM time periods. Each timer has two compare registers

(Data Registers) for generating the PWM set/unset events. Additionally, each timer has a shadow register

(Data Buffer register) which can be used to store CPU updates of compare events while still using the

timer. The selected shadow register update mode happens after the compare event matches.

The counter reset can be configured to happen on a counter roll over, a compare equal event, or by a

software controlled register. Interrupts from the PWM timer can be set due to the counter rollover event

(overflow) or by the two comparison match events. Each comparison match and the overflow interrupts

can be disabled or enabled.

Upon an event comparison, the PWM pin can be configured to set, clear, toggle or have no action at the

output. The value of PWM pin output can be read for status or simply configured as General Purpose I/O

for reading the value of the input at the pin.

6.10.4.3 Watchdog Timer

A watchdog timer is provided on the device for ensuring proper firmware loop execution. The timer is

clocked off of a separate low speed oscillator source. If the timer is allowed to expire, a reset condition is

issued to the ARM processor. The watchdog is reset by a simple CPU write bit to the watchdog key

watchdog cannot be disabled by firmware. Only a device reset can put this bit back to the default disabled

state. A half timer flag is also provided for status monitoring of the watchdog.

6.11 Miscellaneous Analog

The Miscellaneous Analog Control (MAC) Registers provide control and monitor a wide variety of

functions. These functions include device supervisory features such as Brown-Out and power saving

configuration, general purpose input/output configuration and interfacing, internal temperature sensor

control and current sharing control.

The MAC module also provides trim signals to the oscillator and AFE blocks. These controls are usually

used at the time of trimming at manufacturing; therefore this document will not cover these trim controls.

The MAC registers and peripherals are all available in the UCD3138A (64 pin version). Other UCD3138A

devices may have reduced resources. See the device pin out description for details.

6.12 Package ID Information

Package ID register includes information regarding the package type of the device and can be read by

firmware for reporting through PMBus or for other package sensitive decisions.

BIT NUMBER

1:0

Bit Name

PKG_ID

Access

R/W

0 – UCD3138ARGC,

Default

1 – UCD3138ARHA

6.13 Brownout

Brownout function is used to determine if the device supply voltage is lower than a threshold voltage, a

condition that may be considered unsafe for proper operation of the device.

The brownout threshold is higher than the reset threshold voltage; therefore, when the supply voltage is

lower than brownout threshold, it still does not necessarily trigger a device reset.

The brownout interrupt flag can be polled or alternatively can trigger an interrupt to service such case by

an interrupt service routine. See Section 5.7.

Detailed Description

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