Datasheet

NCP5005
http://onsemi.com
5
ANALOG SECTION (Typical values are referenced to T
A
= +25°C, Min & Max values are referenced −25°C to +85°C ambient
temperature, unless otherwise noted.)
Rating Pin Symbol Min Typ Max Unit
High Level Input Voltage
Low Level Input Voltage
4 EN 1.3
−
−
−
−
0.4
V
V
EN Pull Down Resistor 4 R
EN
− 100 − kW
Feedback Voltage Threshold 3 FB 185 200 225 mV
Output Current Stabilization Time Delay following a DC/DC Start−up,
@ V
bat
= 3.60 V, L = 22 mH, I
out
= 20 mA
1 I
outdly
− 100 − ms
Internal Switch ON Resistor @ Tamb = +25°C 1 QR
DSON
− 1.7 − W
5. The overall tolerance depends upon the accuracy of the external resistor.
ESD PROTECTION
The NCP5005 includes silicon devices to protect the pins
against the ESD spikes voltages. To cope with the different
ESD voltages developed in the applications, the built−in
structures have been designed to handle "2.0 kV
in
Human
Body Model (HBM) and "200 V in Machine Model (MM)
on each pin.
DC/DC OPERATION
The DC/DC converter is designed to supply a constant
current to the external load, the circuit being powered from
a standard battery supply. Since the regulation is made by
means of a current loop, the output voltage will varies
depending upon the dynamic impedance presented by the
load.
Considering high intensity LED, the output voltage can
range from a low 6.40 V (two LED in series biased with a
low current), up to 21 V, the voltage compliance the chip
can sustain continuously.
The basic DC/DC structure is depicted in Figure 3. With
a 28 V maximum rating voltage capability, the power
device can accommodate high voltage source without any
leakage current downgrading.
POR
LOGIC
CONTROL
TIME_OUT
ZERO_CROSSING
RESET
GND
Vd
sense
Q1
Vds
L1
22 mH
V
bat
D1
C1
D5 D4 D3 D2
GND
Vs
R2
xR
GND
R1
C2
+
−
GND
Vref
V(Ipeak)
+
−
Vd
sense
Figure 3. Basic DC/DC Converter Structure
1
3
1.0 mF