Datasheet

UCD3138
SLUSAP2F –MARCH 2012 –REVISED NOVEMBER 2013 www.ti.com
4.15.4.2 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.
4.15.4.3 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
register by the firmware routine. On device power-up the watchdog is disabled. Yet after it is enabled, the
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.
4.16 Miscellaneous Analog
The Miscellaneous Analog Control (MAC) Registers are a catch-all of registers that 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 UCD3138 (64 pin version). Other UCD3138
devices may have reduced resources. See the device pin out description for details.
4.17 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 – UCD3138RGC,
Default
1 – UCD3138RHA
4.18 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. Please see the Power On Reset (POR) / Brown Out Reset (BOR) section.
54 Functional Overview Copyright © 2012–2013, Texas Instruments Incorporated
Submit Documentation Feedback
Product Folder Links: UCD3138