MCP19110-ESLASHMJ datasheet(18/226 Pages) MICROCHIP

18 / 226 page

MCP19110/11

DS20002331D-page 18

 2013-2016 Microchip Technology Inc.

3.3

Output Voltage

The output voltage is configured by the settings

contained in the OVCCON and OVFCON registers. No

external resistor divider is needed to set the output

voltage. Refer to Section 6.10 “Output Voltage

Configuration”.

The MCP19110/11 contains a unity gain differential

amplifier used for remote sensing of the output voltage.

Connect the +VSEN and -VSEN pins directly at the load

for better load regulation. The +VSEN and -VSEN are the

positive and negative inputs, respectively, of the

differential amplifier.

3.4

Switching Frequency

The switching frequency is configurable over the range

of 100 kHz to 1.6 MHz. The Timer2 module is used to

generate the HDRV/LDRV switching frequency. Refer

to Section 26.0 “PWM Module” for more information.

Example 3-1

shows

how

configure

the

MCP19110/11 for a switching frequency of 300 kHz.

EXAMPLE 3-1:

CONFIGURING FSW

3.5

Compensation

The MCP19110/11 is an analog peak current mode

controller with integrated adjustable compensation.

The CMPZCON register is used to adjust the

compensation zero frequency and gain. Figure 3-1

shows the internal compensation network with the

output differential amplifier.

FIGURE 3-1:

SIMPLIFIED INTERNAL

COMPENSATION

3.6

Slope Compensation

In current mode control systems, slope compensation

needs to be added to the control path to help prevent

subharmonic oscillation when operating with greater

than 50% duty cycle. In the MCP19110/11, a negative

slope is added to the error amplifier output signal

before it is compared to the current sense signal. The

amount of slope added is controlled by the

SLPCRCON register, Register 6-7.

The amount of slope compensation added should be

equal to the inductor current down slope during the

high-side off time.

3.7

Current Sense

The output current is differentially sensed by the

MCP19110/11. The sense element can be either a

resistor placed in series with the output, or the series

resistance of the inductor. If the inductor series resis-

tance is used, a filter is needed to remove the large AC

component of the voltage that appears across the

inductor and leave only the small AC voltage that

appears across the inductor resistance, as shown in

Figure 3-2. This small AC voltage is representative of

the output current.

FIGURE 3-2:

INDUCTOR CURRENT

SENSE FILTER

The value of RS and CS can be found by using

Equation 3-3. When the current sense filter time

constant is set equal to the inductor time constant, the

voltage appearing across CS approximates the current

flowing in the inductor, multiplied by the inductor

resistance.

BANKSEL

T2CON

CLRF

T2CON

;Turn off Timer2

CLRF

TMR2

;Initialize module

MOVLW

0x19

;Fsw=300 kHz

MOVWF

PR2

MOVLW

0x0A

;Max duty cycle=40%

MOVWF

PWMRL

MOVLW

0x00

;No phase shift

MOVWF

PWMPHL

MOVLW

0x04

;Turn on Timer2

MOVWF

T2CON

VREF

+VSEN

-VSEN

Note 1: To enable the slope compensation

circuitry, the ABECON<SLCPBY> bit

must be cleared.

To Load

-ISEN

+ISEN

HDRV

LDRV

PHASE

LRL

VIN

MCP19110-E/MJ bảng dữ liệu(PDF) 18 Page - Microchip Technology

MCP19110-E/MJ bảng dữ liệu(HTML) 18 Page - Microchip Technology

Html Pages

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75 76 77 78 79 80 81 82 83 84 85 86 87 88 89 90 91 92 93 94 95 96 97 98 99 100 ...More

bảng dữ liệu tải về

Link URL