KIT34844AEPEVBE Freescale Semiconductor, KIT34844AEPEVBE Datasheet - Page 56

• Manufacturer Part Number: KIT34844AEPEVBE
• Description: LED Lighting Development Kits IC, 10 CHANNEL LED BACKLIGHT
• Manufacturer: Freescale Semiconductor

Specifications of KIT34844AEPEVBE

• Supply Voltage: 12 V
• Supply Current: 2 uA
• For Use With/related Products: 34844A
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant

the 34844A, a resistor divider has been implemented from
the PWM pin to ground with a connection to the
compensation network. This configuration should inject a
1.0 V signal to the COMP pin and the equivalent Thevenin
resistance of the divider is close to R
and R
Ampers/Second or as Volts/Second, through the use of the
transfer resistance.
terms of V/
resistor should be set.
PWM
In order to improve the transient response of the boost, on
Slope Compensation
Slope Compensation can be expressed either in terms of
The following formula express the Slope Compensation in
In order to have this slope compensation, the following
COMPONENTS CALCULATION
56
34844
PCOMP
R
PCOMP
μs:
= 27 k for a 5.0 V PWM signal.
C
R
V
COMP
Comp1
SLOPE
C
Comp2
Where “L” is in
=
=
------------------------------------------------------- -
f
Cross
(
--------------------------------------------------- -
Vout Vin
=
C
-------------------------- -
6.28 F
COMP1
×
–
R
L 2
G
Comp
×
2
×
M
COMP
μH
) CSG
SW
×
×
, i.e. R
π 2
C
×
COMP2
COMP
COMP PIN
= 6.8 k
Variable Definition
D= Boost Duty Cycle
V
V
V
V
ΔV
IIN
I
r=Input Current Ratio
IIN
IRMS
IRMS
L= Inductor
R
f
CSG= Current Sense Gain = 0.2 V/A
A
R
C
R
G
ESR
f
f
C
C
V
R
OUT
SW
RHPZ
CROSS
OUT
D
IN
SW
CSA
SLOPE
W
SENSE
OUT
COMP
M
COMP1
COMP2
SLOPE
= Diode Forward Voltage
OUT
AVG
MAX
= Input Voltage
= OTA Transconductance
= Inductor winding DC Resistance
= Boost Switching Frequency
= V
= Output Current
COUT
= Output Voltage
= Current Sense Amplifier Gain = 9
= Output Capacitor
CIN
COUT
= Right Half Plane Zero Frequency
= Output Voltage Ripple Ratio
= Average Input Current
= Maximum input current
= Compensation Resistor
= Crossover Frequency
= Slope Compensation (V/
= External Resistor for Slope Compensation
= Current Sense Resistor = 22mohm
DROP
= Compensation Capacitor
= Shunt Compensation Capacitor
= RMS current for Input Capacitor
= ESR of Output Capacitor
= RMS current for Output Capacitor
of Internal Switch
R
SLOPE
Analog Integrated Circuit Device Data
=
---------------------------- -
V
SLOPE
33
×10
μ
s)
3
×
Freescale Semiconductor
5