AFE5816 Datasheet, PDF (37/162 Pages) Texas Instruments – 16-Channel Ultrasound AFE

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AFE5816
SBAS688D – APRIL 2015 – REVISED NOVEMBER 2015
9.3.5.2.1.1 Profile Selection
When programmed, there are two ways that any one of the four profiles can be selected and switched to
program the settings in the TGC mode: either with the device pin or by register settings.
1. Device pin. To select the profile using pin control, set the PROFILE_EXT_DIS bit to 0. Then, the different
combinations of logic level at the TGC_PROF<2> and TGC_PROF<1> pins listed in Table 6 dictate which
profile is selected.
2. Register settings. To select the profile with register settings, set the PROFILE_EXT_DIS bit to 1. Then, the
different combinations of the PROFILE_REG_SEL bits listed in Table 6 dictate which profile must be used to
program the corresponding TGC mode.
Table 6. Profile Selection Using the Device Pin or the PROFILE_REG_SEL Bits
PIN CONTROL (PROFILE_EXT_DIS = 0)
TGC_PROF<2>
TGC_PROF<1>
0
0
0
1
1
0
1
1
REGISTER CONTROL (PROFILE_EXT_DIS = 1)
PROFILE_REG_SEL
00
01
10
11
SELECTED PROFILE
Profile 0
Profile 1
Profile 2
Profile 3
9.3.5.3 DTGC Modes
The device supports four schemes to change the device gain. These schemes are referred to as the four DTGC
modes. The device can be programmed in any of these modes by using the MODE_SEL register bit, as shown in
Table 7.
Table 7. DTGC Modes
MODE_SEL REGISTER BITS SETTING
10
01
00
11
DTGC MODE
Programmable fixed-gain
Up, down ramp
External non-uniform
Internal non-uniform
9.3.5.3.1 Programmable Fixed-Gain Mode
In this mode, the device gain is set directly by writing a gain code in the MANUAL_GAIN_DTGC register. See
Figure 2 for a description of device gain versus gain code across power modes. Note that the allowed value of
the gain code is from 0 to 319. The gain codes from 0 to 63 control the attenuator and the codes from 64 to 319
control the LNA. If the gain code is programmed outside the 0 to 319 range, then the gain code value
automatically becomes 0.
For Low-Noise or Medium-Power mode: Gain = 6 + Gain code × 0.125
For Low-Power mode: Gain = 12 + Gain code × 0.125
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