LT1508 Datasheet, PDF (2/16 Pages) Linear Technology – Power Factor and PWM Controller(Voltage Mode)

LT1508
DESCRIPTION
By using fixed high frequency PWM current averaging
without the need for slope compensation, the LT1508
achieves far lower line current distortion with a smaller
magnetic element than systems that use either peak
current detection, or zero current switching approach, in
both continuous and discontinuous modes of operation.
The LT1508 also provides filtering capability to reject line
switching noise which can cause instability when fed into
the multiplier. Line current dead zone is minimized with
low bias voltage at the current input to the multiplier. The
LT1508 provides many protection features including peak
current limiting and overvoltage protection. Implemented
with a very high speed process, the LT1508 can be
operated at frequencies as high as 300kHz.
ABSOLUTE MAXIMUM RATINGS
Supply Voltage ........................................................ 27V
GTDR Current Continuous ...................................... 0.5A
GTDR Output Energy ................................................ 5µJ
I_AC, R_SET, PK_LIM Input Current .............................. 20mA
V_SENSE, OVP Input Voltage .................................... V_MAX
I_LIM, V_C Input Voltage ................................................ 8V
I_SENSE, M_OUT Input Current ................................... ±5mA
Operating Junction Temperature Range
LT1508C ................................................ 0°C to 100°C
LT1508I ............................................ – 40°C to 125°C
Thermal Resistance (Junction-to-Ambient)
N Package ................................................... 100°C/W
SW Package ................................................ 120°C/W
PACKAGE/ORDER INFORMATION
TOP VIEW
GTDR1 1
GND2 2
GND1 3
C_SET 4
PK_LIM 5
CA_OUT 6
I_SENSE 7
M_OUT 8
I_AC 9
VA_OUT 10
20 GTDR2
19 I_LIM
18 V_C
17 V_CC
16 SS1
15 R_SET
14 V_SENSE
13 SS2
12 V_REF
11 OVP
N PACKAGE
20-LEAD PDIP
SW PACKAGE
20-LEAD PLASTIC SO WIDE
T_JMAX = 125°C, θ_JA = 100°C/ W (N)
T_JMAX = 125°C, θ_JA = 120°C/ W (SW)
Consult factory for Military grade parts.
ORDER PART
NUMBER
LT1508CN
LT1508CSW
LT1508IN
LT1508ISW
ELECTRICAL CHARACTERISTICS
Maximum operating voltage (V_MAX) = 25V, V_CC = 18V, R_SET = 15k to GND, C_SET = 1nF to GND, I_AC = 100µA, I_SENSE = 0V, CA_OUT = 3.5V,
VA_OUT = 5V, OVP = V_REF. No load on any outputs unless otherwise noted.
PARAMETER
Overall
Supply Current (V_CC in Undervoltage Lockout)
Supply Current On
V_CC Turn-On Threshold (Undervoltage Lockout)
V_CC Turn-Off Threshold
Voltage Amplifier (PFC Section)
Voltage Amp Offset
Input Bias Current
Voltage Gain
Voltage Amp Unity-Gain Bandwidth
Voltage Amp Output High (Internally Clamped)
Voltage Amp Output Low
Voltage Amp Short-Circuit Current
CONDITIONS
V_CC = Lockout Voltage – 0.2V
11.5V ≤ V_CC ≤ V_MAX
VA_OUT = 3.5V
V_SENSE = 0V to 7V
VA_OUT = 0V
MIN TYP MAX
UNITS
q
0.25 0.45
mA
q
13
19
mA
q 15.5 16.5 17.5
V
q
9.5
10.5 11.5
V
q
– 10
10
mV
q
– 25 – 250
nA
70
100
dB
3
MHz
q 11.3 13.3
V
q
1.1
2
V
q
3
8
17
mA
2