ZL2004 datasheet(23/42 Pages) RENESAS

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ZL2004

FN6846 Rev. 3.00

Page 23 of 42

February 15, 2011

In addition to selecting the current sensing method, the

ZL2004 gives the power supply designer several

choices for the fault response during over or under

current condition. The user can select the number of

violations allowed before declaring fault, a blanking

time and the action taken when a fault is detected.

The blanking time represents the time when no current

measurement is taken. This is to avoid taking a reading

just after a current load step (less accurate due to

potential ringing). It is a configurable parameter.

ZL2004 provides an adjustable maximum full scale

sensing range. The range can be adjusted from 25 mV

to 50 mV using pin-strap or resistor setting method

described in Table 17 and Table 18.

Table 17 includes default parameters for the number of

violations and the blanking time using pin-strap.

Table 17. Pin-strap Settings for Current Sensing

ILIM Pin

Current Limiting Configuration

Number of

Violations

Allowed2

Current Limit

Threshold

VLIM

Maximum

Current Sensing

Range

LOW

Output-referenced, down-slope sensing

(Inductor DCR sensing)

Blanking time: 224 ns

25 mV

OPEN

Output-referenced, down-slope sensing

(Inductor DCR sensing)

Blanking time: 224 ns

35 mV

HIGH

Output-referenced, down-slope sensing

(Inductor DCR sensing)

Blanking time: 224 ns

50 mV

Resistor1

Depends on resistor value used; see Table 18

Notes:

1. 10 kΩ < R

ILIM0 < 100 kΩ

2. The number of violations allowed prior to issuing a fault response.

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