ZL2004 datasheet(10/42 Pages) RENESAS

10 / 42 page

ZL2004

FN6846 Rev. 3.00

Page 10 of 42

February 15, 2011

4.2 Power Conversion Overview

The ZL2004 operates as a voltage-mode, synchronous

buck converter with a selectable constant frequency

pulse width modulator (PWM) control scheme that

uses external driver, MOSFETs, capacitors, and an

inductor to perform power conversion.

ZL2004

DRIVER

VIN

VOUT

Figure 5. Synchronous Buck Converter

Figure 5 illustrates the basic synchronous buck

converter topology showing the primary power train

components. This converter is also called a step-down

converter, as the output voltage must always be lower

than the input voltage.

Dual output PWM ZL2004

The ZL2004 provides a dual PWM signal which

removes

the

need

tri-state

function

and

significantly improves conversion performance.

The ZL2004 has been designed to drive the QH and

QL independently, allowing greater control of the

MOSFETs and higher overall performance. A special

driver with two PWM inputs is required (ZL1505).

Using two PWM signals (PWMH and PWML) offers

options

during

fault

event

and

pre-bias

conditions, eliminating the need for a tri-state driver

and reducing the delays associated with this scheme.

The ZL2004 has several features to improve the power

conversion efficiency. A non-linear response (NLR)

loop improves the response time and reduces the

output deviation as a result of a load transient. The

ZL2004 monitors the power converter’s operating

conditions and continuously adjusts the turn-on and

turn-off

timing

the

high-side

and

low-side

MOSFETs to optimize the overall efficiency of the

power supply. Adaptive performance optimization

algorithms such as dead-time control, diode emulation,

Figure 4. ZL2004 Block Diagram

Digital

Compensator

I2C

NLR

Input Voltage Bus

OUT

D-PWM



VSEN+

SYNC

PLL

Power Management

TEMP

Sensor

MUX

XTEMP

VMON

MGN

V(0,1)

SA(0,1)

VSEN

ISENB

ILIM

VDD

MOSFET

Pre

Drivers

SYNC

GEN

VTRK

ISENA

VDD

SCL

SDA

SALRT

ADC

Communication

DAC

REFCN

DDC

Voltage

Sensor

VSEN-

NVM

Driver

MOSFET

PWMH

PWML

LDO

Digital

Compensator

I2C

NLR

Input Voltage Bus

OUT

D-PWM



VSEN+

SYNC

PLL

Power Management

TEMP

Sensor

MUX

XTEMP

VMON

MGN

V(0,1)

SA(0,1)

VSEN

ISENB

ILIM

VDD

MOSFET

Pre

Drivers

SYNC

GEN

VTRK

ISENA

VDD

SCL

SDA

SALRT

ADC

Communication

DAC

REFCN

DDC

Voltage

Sensor

VSEN-

NVM

Driver

MOSFET

PWMH

PWML

LDO

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