AMD Vega 10 User Manual

Table 4–5 Backlight PWM Parameters
Parameter Description Min Typ Max Unit
REF
xtal_freq or xtal_freq × 2 —
27
or
54
— MHz
F
PWM
Backlight PWM signal frequency.
= REF / ( [ (BL_PWM_PERIOD) ×
(BL_PWM_REF_DIV) ] )
where REF is the input reference clock frequency (typically 27 or
54 MHz), BL_PWM_REF_DIV is a 16-bit value specifying the division
factor for this input reference clock, and BL_PWM_PERIOD is a 16-
bit value representing the period of the backlight PWM signal in
units of divided input reference clock cycles.
Typical Range: 55 Hz to 50 kHz.
0.007 — 13 M Hz
R
DUTY
Active duty cycle ratio.
= (BL_ACTIVE_INT_FRAC_CNT) / (BL_PWM_PERIOD)
Minimum duty cycle increment size is (1/65535) of
BL_PWM_PERIOD.
0 — 100 %
The backlight pulse width modulation circuit generates a backlight PWM signal with
a frequency:
= REFCLK / ( [ (BL_PWM_PERIOD) * (BL_PWM_REF_DIV) ] )
REFCLK is the input reference clock frequency (typically 27 or 54 MHz).
BL_PWM_REF_DIV is a 16-bit value specifying the division factor for this input reference
clock.
BL_PWM_PERIOD is a 16-bit value representing the period of the backlight PWM signal
in units of divided input reference clock cycles.
To set the backlight modulation,
1. Set the coarse frequency by selecting BL_PWM_REF_DIV:
BL_PWM_REF_DIV = ceil (REF / (65535 ×
FTARGET))
2. Compute the fine frequency by selecting the period BL_PWM_PERIOD:
BL_PWM_PERIOD = ceil (REF / (FTARGET ×
BL_PWM_REF_DIV))
The period should be a value between 1 and 65535.
3. Compute the actual frequency:
FINIT = REF / ((BL_PWM_PERIOD) ×
(BL_PWM_REF_DIV))
4. Compute the relative error:
EINIT = (FTARGET – FINIT) / FTARGET
Note:
• For 50-kHz FTARGET, EINIT will equal zero (no error).
• For 55-Hz FTARGET, EINIT will be less than 0.0006%.
• The number of usable steps for the active duty cycle is (BL_PWM_PERIOD
+ 1), that is from 0% up to 100% active duty cycle.
Timing Specifications 55
© 2017 Advanced Micro Devices, Inc.
AMD Confidential - Do not duplicate.
"Vega 10" Databook
56006_1.00

AMD Vega 10 Specifications

General

Process Size	14 nm
Transistor Count	12.5 billion
Memory Type	HBM2
GPU	Vega 10
Stream Processors	4096
Texture Units	256
ROPs	64
Memory Size	8 GB
Die Size	486 mm²
Memory Bandwidth	483.8 GB/s
Compute Units	64
FP32 (float) Performance	12.66 TFLOPS
Memory Bus	2048-bit