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PRELIMINARY

PSoC® 5: CY8C53 Family Datasheet

Document Number: 001-66237 Rev. *A

Page 51 of 106

8.5.3 PGA

The PGA amplifies an external or internal signal. The PGA can

be configured to operate in inverting mode or noninverting mode.

The PGA function may be configured for both positive and

negative gains as high as 50 and 49 respectively. The gain is

adjusted by changing the values of R1 and R2 as illustrated in

Figure 8-7. The schematic in Figure 8-7 shows the configuration

and possible resistor settings for the PGA. The gain is switched

from inverting and non inverting by changing the shared select

value of the both the input muxes. The bandwidth for each gain

case is listed in Table 8-2.

Figure 8-7. PGA Resistor Settings

The PGA is used in applications where the input signal may not

be large enough to achieve the desired resolution in the ADC, or

dynamic range of another SC/CT block such as a mixer. The gain

is adjustable at runtime, including changing the gain of the PGA

prior to each ADC sample.

8.5.4 TIA

The Transimpedance Amplifier (TIA) converts an internal or

external current to an output voltage. The TIA uses an internal

feedback resistor in a continuous time configuration to convert

input current to output voltage. For an input current Iin, the output

voltage is VREF - Iin x Rfb, where VREF is the value placed on the

non inverting input. The feedback resistor Rfb is programmable

between 20 K

Ω and 1 MΩ through a configuration register.

Table 8-3 shows the possible values of Rfb and associated

configuration settings.

Figure 8-8. Continuous Time TIA Schematic

The TIA configuration is used for applications where an external

sensor's output is current as a function of some type of stimulus

such as temperature, light, magnetic flux etc. In a common

application, the voltage DAC output can be connected to the

VREF TIA input to allow calibration of the external sensor bias

current by adjusting the voltage DAC output voltage.

8.6 LCD Direct Drive

The PSoC Liquid Crystal Display (LCD) driver system is a highly

configurable peripheral designed to allow PSoC to directly drive

a broad range of LCD glass. All voltages are generated on chip,

eliminating the need for external components. With a high

multiplex ratio of up to 1/16, the CY8C53 family LCD driver

system can drive a maximum of 736 segments. The PSoC LCD

driver module was also designed with the conservative power

budget of portable devices in mind, enabling different LCD drive

modes and power down modes to conserve power.

PSoC Creator provides an LCD segment drive component. The

component wizard provides easy and flexible configuration of

LCD resources. You can specify pins for segments and

commons along with other options. The software configures the

device to meet the required specifications. This is possible

because of the programmability inherent to PSoC devices.

Key features of the PSoC LCD segment system are:

LCD panel direct driving

Type A (standard) and Type B (low power) waveform support

Wide operating voltage range support (2 V to 5 V) for LCD

panels

Table 8-2. Bandwidth

Gain

Bandwidth

6.0 MHz

340 kHz

220 kHz

215 kHz

20 k to 980 k

20 k or 40 k

Vin

Vref

Vin

Table 8-3. Feedback Resistor Settings

Configuration Word

Nominal Rfb (KΩ)

000b

001b

010b

011b

100b

120

101b

250

110b

500

111b

1000

V ref

Vout

I in

R fb

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