PSoC Device Internals, + C9 | Cypress CY8C24794, AN2309, CY8C29x66

AN2309

Figure 5. Two-Cell Battery Charger Schematic – Power Supply and User Interface

SW1

J4+

POWER 12V DC

BAT+

R30

POWER+

33BAT54C

POWER+ MBR360

BAT+

MBR360

R26

LOAD_EN

330R

POWER+

+ C9			C10


100u 16V			0.1u 16V

POWER-

U2 L78L05/TO

IN OUT

C12

+ C11

0.33u 16V

100u 16V

R25 IRLML6402

Q7 LED_YELLOW BC817

R27

10K

LED_GREEN

VCC

	Close to PSoC
R29		VCC
1K
	Vbias	C15
	Vbias
D8		0.1u
BAS16
		VCC
		R28
		470
+ C13	C14	D7
		D7
22u	0.1u
		POWER
		PSoC

LOAD

R2	D2
470

LED

R3 D3

470

LED

PSoC Device Internals

The internal structure of the PSoC device is shown in Figure 6 on page 9. The PWM is placed on DBB01 and DCB02. The module is configured in the software as an 11-bit PWM, which provides for a sufficient number of regulation steps. The TIMER User Module is based on the internal sleep timer and configured to generate interrupts every one second. This real clock is used to calculate other time intervals. The serial transmitter is placed into DCB03. The default exchange speed is set to 115200 baud.

The cell-balancing MOSFETS Q4, Q5 are controlled directly from the CPU (high level - close, low level - open).

The three-opamp topology of the instrumental amplifier (INA) is used in this implementation. The INA is placed in ACB00, ACB01, and ASD11. The incremental ADC is placed in the ASC10 and DBB00 blocks.

The ADC resolution is set to 12 bits, and the integration time is adjusted to be precisely equal to the integer number of the PWM signal. All of the switched capacitor user modules use the same column frequency to eliminate aliasing problems. In this project, the analog ground bias was set to bandgap or 1.3V (RefMux is BandGap ± BandGap).

Note that if you require more program memory and analog pins, or require USB support, in your user-defined projects, you can import this charger to the CY8C24794 or the CY8C27x43 PSoC device family. The CY8C24794 device includes a full-featured, full-speed (12 Mbps) USB port and can have up to seven IO ports that connect to the global digital and analog interconnects, providing access to four digital blocks and six analog blocks. For additional information, see “Products: PSoC Mixed-Signal Controllers:

PSoC Mixed-Signal Array: CY8C24794” on www.cypress.com.

November 25, 2007

Document No. 001-17394 Rev. *B

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