CTB (Continuous Time Block)

General Description

This driver provides API functions to configure the CTB subsystem of the Autonomous Analog.

The CTB block provides operational amplifiers (Opamps) for use in continuous-time signal chains. Each CTB includes two identical Opamps marked OA0 and OA1, a switch matrix for input/output routing, and the resistor ladder for each Opamp gain setting.

For more information on the CTB, refer to the device Architecture Technical Reference Manual (TRM).
For the exact location of the pins, see the device datasheet.

Static Configuration

The static configuration contains application-specific settings intended to remain static for any Opamp application. The Autonomous Controller (AC) will NOT change the static configuration during operation.

The static configuration of the Opamp includes:

• Power mode;
• Topology;
• Interrupt mode (Comparator only);
• Opamp compensation;
  For configuration settings, see cy_stc_autanalog_ctb_sta_t.

The Opamp topology in the CTB can be configured as follows:

• Comparator (with or without hysteresis);

  Note

  The comparator output is not connected to pin and can only be used as an interrupt or trigger source.

• Programmable Gain Amplifier (PGA, inverting and non-inverting, ground and Vref referenced);
• Trans-impedance Amplifier (TIA);
• Opamp with open loop (Potentiostat);
• Differential Amplifier (DiffAmp);
• Buffer (Voltage follower).

Dynamic Configuration and State Transition Table

The dynamic configuration structure includes the Opamp settings, which can be modified by the Autonomous Controller (AC) during operation.

The Autonomous Controller is able to modify the following characteristics of the CTB in runtime per settings provided in the State Transition Table:

• Enable/Disable Opamp within the CTB;
• Re-configure the switch matrix:
  • change the connection of the non-inverting Opamp input to the pin or voltage reference;
  • change the connection of the inverting Opamp input to the pin;
  • change the connection of the bottom end of the resistor ladder to the pin or voltage reference;
• Adjust the Opamps gain;

For the configuration settings, see cy_stc_autanalog_ctb_dyn_t and cy_stc_autanalog_stt_ctb_t.

The gain settings for each topology are as follows:

Index	Gain	R-ladder, Ohm	Non-inv PGA	Inv PGA	DiffAmp	TIA
0	1.00	Rin = 192k, Rfb = 0	1.00	0	1.00	0k
1	1.42	Rin = 135k, Rfb = 57k	1.42	0.42	1.42	Rfb = 57k
2	2.00	Rin = 96k, Rfb = 96k	2.00	1.00	2.00	Rfb = 96k
3	2.78	Rin = 69k, Rfb = 123k	2.78	1.78	2.78	Rfb = 123k
4	4.00	Rin = 48k, Rfb = 144k	4.00	3.00	4.00	Rfb = 144k
5	5.82	Rin = 33k, Rfb = 159k	5.82	4.82	5.82	Rfb = 159k
6	8.00	Rin = 24k, Rfb = 168k	8.00	7.00	8.00	Rfb = 168k
7	10.67	Rin = 18k, Rfb = 174k	10.67	9.67	10.67	Rfb = 174k
8	16.00	Rin = 12k, Rfb = 180k	16.00	15.00	16.00	Rfb = 180k
9	21.33	Rin = 9k, Rfb = 183k	21.33	20.33	21.33	Rfb = 183k
10	32.00	Rin = 6k, Rfb = 186k	32.00	31.00	32.00	Rfb = 186k

Note

For more information on the operating principles of the Autonomous Controller (static and dynamic configurations, State transition Table, etc.), refer to the corresponding chapter AC (Autonomous Controller).

Opamp Input and Output Ranges

The input range of the Opamp can be rail-to-rail if the charge pump is enabled. Without the charge pump, the input range is 0 V to VDDA - 1.5 V. The output range of the Opamp is typically 0.2 V to VDDA - 1.0 V and will depend on the load. See the device datasheet for more details.

Charge Pump	Input Range	Output Range
Enabled	0 V to VDDA	0.2 V to VDDA - 0.2 V
Disabled	0 V to VDDA - 1.5 V	0.2 V to VDDA - 1.0 V

Note

The charge pump nominal clock is 4MHz

For the configuration settings, see cy_en_autanalog_ctb_oa_pwr_t.

Opamp compensation

The Opamp stability is affected by the phase delay caused by the resistance in the Opmap feedback and parasitic capacitance at the Opamp input. Therefore, a 4-bit programmable compensation capacitor block is added in parallel with the resistor in the Opmap feedback to optimize the stability of the Opamp performance. For the configuration settings, see cy_en_autanalog_ctb_oa_fb_cap_t and cy_en_autanalog_ctb_oa_cc_cap_t.

Note

Use the Autonomous Analog Configurator to define the actual capacitance value required for a particular configuration.

Sample use case: inverting PGA and Comparator

 
/* Define the index for CTB0 instance within the Autonomous Analog */
#define CTB0IDX                                                (0U)
/* Define the index for CTB1 instance within the Autonomous Analog */
#define CTB1IDX                                                (1U)
 
/* Define the index for Opamp0 within the CTB */
#define OPAMP0IDX                                              (0U)
/* Define the index for Opamp1 within the CTB */
#define OPAMP1IDX                                              (1U)
 

 
/* Scenario 1:
* CTB0 configured to operate in Ultra-low power mode
* - Opamp0: Inverting the ground-referenced PGA with gain setting 15.00. The charge pump is enabled.
* - Opamp1: Comparator with hysteresis;
* Note: The values for the FB and CC capacitors are given only as examples.
*/
/* The static part of the configuration for the CTB0 */
static cy_stc_autanalog_ctb_sta_t ctb0StaticCfgPGA =
{
    /* CTB0, Opamp0 */
    .pwrOpamp0        = CY_AUTANALOG_CTB_OA_PWR_ULTRA_LOW_RAIL,
    .topologyOpamp0   = CY_AUTANALOG_CTB_OA_TOPO_PGA,
    .intComp0         = CY_AUTANALOG_CTB_COMP_INT_EDGE_DISABLED,
    .capCcOpamp0      = CY_AUTANALOG_CTB_OA_CC_CAP_2_1_pF,
    .capFbOpamp0      = CY_AUTANALOG_CTB_OA_FB_CAP_3_5_pF,
 
    /* CTB0, Opamp1 */
    .pwrOpamp1        = CY_AUTANALOG_CTB_OA_PWR_ULTRA_LOW_RAIL,
    .topologyOpamp1   = CY_AUTANALOG_CTB_OA_TOPO_HYST_COMPARATOR,
    .intComp1         = CY_AUTANALOG_CTB_COMP_INT_EDGE_BOTH,
    .capCcOpamp1      = CY_AUTANALOG_CTB_OA_CC_CAP_0_1_pF,
    .capFbOpamp1      = CY_AUTANALOG_CTB_OA_FB_CAP_0_pF,
};
 
/* The dynamic part of the configuration for the CTB0 */
static cy_stc_autanalog_ctb_dyn_t ctb0DynamicCfgPGA[] =
{
    /* CTB0, Opamp0 */
    {
        .ninvInpPin   = CY_AUTANALOG_CTB_OA_NINV_PIN_OA0_P0_OA1_P5,
        .ninvInpRef   = CY_AUTANALOG_CTB_OA_NINV_REF_DISCONNECT,
        .invInpPin    = CY_AUTANALOG_CTB_OA_INV_PIN_DISCONNECT,
        .resInpPin    = CY_AUTANALOG_CTB_OA_RES_PIN_OA0_P1_OA1_P4,
        .resInpRef    = CY_AUTANALOG_CTB_OA_RES_REF_DISCONNECT,
        .sharedMuxIn  = CY_AUTANALOG_CTB_OA_MUX_IN_DISCONNECT,
        .sharedMuxOut = CY_AUTANALOG_CTB_OA_MUX_OUT_DISCONNECT,
        .outToPin     = true,
    },
 
    /* CTB0, Opamp1 */
    {
        .ninvInpPin   = CY_AUTANALOG_CTB_OA_NINV_PIN_DISCONNECT,
        .ninvInpRef   = CY_AUTANALOG_CTB_OA_NINV_REF_PRB_OUT0,
        .invInpPin    = CY_AUTANALOG_CTB_OA_INV_PIN_OA0_P1_OA1_P4,
        .resInpPin    = CY_AUTANALOG_CTB_OA_RES_PIN_DISCONNECT,
        .resInpRef    = CY_AUTANALOG_CTB_OA_RES_REF_DISCONNECT,
        .sharedMuxIn  = CY_AUTANALOG_CTB_OA_MUX_IN_DISCONNECT,
        .sharedMuxOut = CY_AUTANALOG_CTB_OA_MUX_OUT_DISCONNECT,
        .outToPin     = false,
    },
};
 
/* Total configuration for the CTB0 */
cy_stc_autanalog_ctb_t ctb0CfgPGA =
{
    .ctbStaCfg    = &ctb0StaticCfgPGA,
    .ctbDynCfgNum = sizeof(ctb0DynamicCfgPGA) / sizeof(ctb0DynamicCfgPGA[0U]),
    .ctbDynCfgArr = ctb0DynamicCfgPGA,
};
 
/* The State Transition Table configuration for the CTB0 */
cy_stc_autanalog_stt_ctb_t ctb0TtPGA[] =
{
    /* The single state configuration in the State Transition Table */
    {
        /* Enable the configuration for state #0 */
        .unlock = true,
 
        /* CTB0, Opamp0 */
        .enableOpamp0 = true,
        .cfgOpamp0    = OPAMP0IDX,
        .gainOpamp0   = CY_AUTANALOG_STT_CTB_OA_GAIN_16_00,
 
        /* CTB0, Opamp1 */
        .enableOpamp1 = true,
        .cfgOpamp1    = OPAMP1IDX,
        .gainOpamp1   = CY_AUTANALOG_STT_CTB_OA_GAIN_1_00,
    },
};
 

 
    cy_en_autanalog_status_t status;
 

 
    status = Cy_AutAnalog_CTB_LoadConfig(CTB0IDX, &ctb0CfgPGA);
    if (CY_AUTANALOG_SUCCESS != status)
    {
        /* Error handling */
    }
 

Sample use case: non-inverting PGA and Voltage follower

 
/* Define the index for CTB0 instance within the Autonomous Analog */
#define CTB0IDX                                                (0U)
/* Define the index for CTB1 instance within the Autonomous Analog */
#define CTB1IDX                                                (1U)
 
/* Define the index for Opamp0 within the CTB */
#define OPAMP0IDX                                              (0U)
/* Define the index for Opamp1 within the CTB */
#define OPAMP1IDX                                              (1U)
 

 
/* Scenario 2:
* CTB1 configured to operate in Ultra-low power mode
* - Opamp0: Non-inverting the ground-referenced PGA with gain setting 8.00. The charge pump is enabled.
* - Opamp1: Voltage follower;
* Note: The values for FB and CC capacitors are given only as examples.
*/
 
/* The static part of the configuration for CTB1 */
static cy_stc_autanalog_ctb_sta_t ctb1StaticCfgPGA =
{
    /* CTB1, Opamp0 */
    .pwrOpamp0        = CY_AUTANALOG_CTB_OA_PWR_ULTRA_LOW,
    .topologyOpamp0   = CY_AUTANALOG_CTB_OA_TOPO_PGA,
    .intComp0         = CY_AUTANALOG_CTB_COMP_INT_EDGE_DISABLED,
    .capCcOpamp0      = CY_AUTANALOG_CTB_OA_CC_CAP_5_1_pF,
    .capFbOpamp0      = CY_AUTANALOG_CTB_OA_FB_CAP_7_7_pF,
 
    /* CTB1, Opamp1 */
    .pwrOpamp1        = CY_AUTANALOG_CTB_OA_PWR_ULTRA_LOW,
    .topologyOpamp1   = CY_AUTANALOG_CTB_OA_TOPO_BUFFER,
    .intComp1         = CY_AUTANALOG_CTB_COMP_INT_EDGE_DISABLED,
    .capCcOpamp1      = CY_AUTANALOG_CTB_OA_CC_CAP_1_1_pF,
    .capFbOpamp1      = CY_AUTANALOG_CTB_OA_FB_CAP_0_pF,
};
 
/* The dynamic part of the configuration for CTB1 */
static cy_stc_autanalog_ctb_dyn_t ctb1DynamicCfgPGA[] =
{
    /* CTB1, Opamp0 */
    {
        .ninvInpPin   = CY_AUTANALOG_CTB_OA_NINV_PIN_OA0_P0_OA1_P5,
        .ninvInpRef   = CY_AUTANALOG_CTB_OA_NINV_REF_DISCONNECT,
        .invInpPin    = CY_AUTANALOG_CTB_OA_INV_PIN_DISCONNECT,
        .resInpPin    = CY_AUTANALOG_CTB_OA_RES_PIN_DISCONNECT,
        .resInpRef    = CY_AUTANALOG_CTB_OA_RES_REF_VSSA,
        .sharedMuxIn  = CY_AUTANALOG_CTB_OA_MUX_IN_DISCONNECT,
        .sharedMuxOut = CY_AUTANALOG_CTB_OA_MUX_OUT_DISCONNECT,
        .outToPin     = true,
    },
 
    /* CTB1, Opamp1 */
    {
        .ninvInpPin   = CY_AUTANALOG_CTB_OA_NINV_PIN_OA0_P0_OA1_P5,
        .ninvInpRef   = CY_AUTANALOG_CTB_OA_NINV_REF_DISCONNECT,
        .invInpPin    = CY_AUTANALOG_CTB_OA_INV_PIN_DISCONNECT,
        .resInpPin    = CY_AUTANALOG_CTB_OA_RES_PIN_DISCONNECT,
        .resInpRef    = CY_AUTANALOG_CTB_OA_RES_REF_DISCONNECT,
        .sharedMuxIn  = CY_AUTANALOG_CTB_OA_MUX_IN_DISCONNECT,
        .sharedMuxOut = CY_AUTANALOG_CTB_OA_MUX_OUT_DISCONNECT,
        .outToPin     = true,
    },
};
 
/* The total configuration for CTB1 */
cy_stc_autanalog_ctb_t ctb1CfgPGA =
{
    .ctbStaCfg    = &ctb1StaticCfgPGA,
    .ctbDynCfgNum = sizeof(ctb1DynamicCfgPGA) / sizeof(ctb1DynamicCfgPGA[0U]),
    .ctbDynCfgArr = ctb1DynamicCfgPGA,
};
 
/* The State Transition Table configuration for CTB1 */
cy_stc_autanalog_stt_ctb_t ctb1TtPGA[] =
{
    /* The single state configuration in the State Transition Table */
    {
        /* Enable the configuration for state #0 */
        .unlock = true,
 
        /* CTB1, Opamp0 */
        .enableOpamp0 = true,
        .cfgOpamp0    = OPAMP0IDX,
        .gainOpamp0   = CY_AUTANALOG_STT_CTB_OA_GAIN_8_00,
 
        /* CTB1, Opamp1 */
        .enableOpamp1 = true,
        .cfgOpamp1    = OPAMP1IDX,
        .gainOpamp1   = CY_AUTANALOG_STT_CTB_OA_GAIN_1_00,
    },
};
 

Note

The configuration must only be done while the AC is in High Speed mode, when cy_stc_autanalog_stt_ac_t::lpMode is equal to FALSE.

 
    cy_en_autanalog_status_t status;
 

 
    status = Cy_AutAnalog_CTB_LoadConfig(CTB1IDX, &ctb1CfgPGA);
    if (CY_AUTANALOG_SUCCESS != status)
    {
        /* Error handling */
    }
 

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