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SLUUBD3D–September 2015–Revised September 2018
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Copyright © 2015–2018, Texas Instruments Incorporated
Display Port
Chapter 13
SLUUBD3D–September 2015–Revised September 2018
Display Port
13.1 Introduction
The Display Port feature can provide a visual display of RelativeStateofCharge() or
AbsoluteStateOfCharge(), and can be activated in several ways. This feature can use LEDs or a 5-bar
LCD and has a variety of configuration options to enable a wide range of indications.
The bq78350-R1 display type is set in LED Configuration [LCDEN]. When [LCDEN] = 0, the display type
is LED; when [LCDEN] = 1, the display type is LCD.
13.1.1 Light Emitting Diode (LED) Display Operation
The LED display is the default display type for the bq78350-R1. When the LED display is activated, the
device turns on the appropriate LEDs through the LED1..5 pins when a push button is pressed or a
command is sent to the device.
13.1.2 Liquid Crystal Display (LCD) Operation
The LCD controller supports 3- to 5-segment static bar graph liquid crystal displays (LCDs). The LCD is
operational at all times except when the bq78350-R1 is in the SHUTDOWN power mode.
A static LCD generally has one large electrode on one side of the liquid crystal material called a
"common," and a number of smaller electrodes on the other side called "segments." Segments are made
visible (black) by applying a differential voltage between the back plane signal of the LCD and the
corresponding segment pin. Segments are turned off when there is no voltage difference between the
back plane signal and a segment signal. The display signals must be periodically reversed to ensure zero
average DC voltage and to refresh the display.
Liquid crystal displays having an operating voltage range of 2.5 V to 6 V and a refresh frequency between
30 Hz and 200 Hz are supported. The display refresh must be implemented such that the device current
consumption requirements during sleep and active modes are not violated. The display refresh frequency
must always be set as low as the LCD specification allows in order to minimize current consumption.
Static LCD drive procedure is as follows:
• Step 1. Drive back plane to ground, drive "on" segments high, "off" segments to ground.
• Step 2. Wait for time 1/refresh frequency.
• Step 3. Drive back plane high, drive "on" segments to ground, "off" segments high.
• Step 4. Wait for time 1/refresh frequency.
• Step 5. Go to Step 1.
13.2 Display Activation
13.2.1 LED Display Activation
The LED display is activated for a period of LED Hold Time:
• If the DISP pin is low for < LED Hold Time.
• If [LEDR] = 1 AND the device is Reset.
• If [LEDCHG] = 1 AND Current() > 0.
• If ManufacturerStatus() = 0x002C.
If SafetyStatus() [CUV] flag is set, the display is disabled.
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