LM3578AM datasheet(3/30 Pages) TI

3 / 30 page

LM2578A, LM3578A

www.ti.com

SNVS767E – AUGUST 2000 – REVISED APRIL 2013

Electrical Characteristics

These specifications apply for 2V

≤ VIN ≤ 40V (2.2V ≤ VIN ≤ 40V for TJ ≤ −25°C), timing capacitor CT = 3900 pF, and 25% ≤

duty cycle

≤ 75%, unless otherwise specified. Values in standard typeface are for TJ = 25°C; values in boldface type apply

for operation over the specified operating junction temperature range.

Typical(1)

LM2578A/

Symbol

Parameter

Conditions

LM3578A

Units

Limit (2)

OSCILLATOR

fOSC

Frequency

kHz

kHz (max)

kHz (min)

ΔfOSC/ΔT

Frequency Drift with Temperature

−0.13

%/°C

Amplitude

550

mVp-p

REFERENCE/COMPARATOR(3)

Input Reference

I1 = I2 = 0 mA and

1.0

Voltage

I1 = I2 = 1 mA ±1%

(4)

1.050/1.070

V (max)

0.950/0.930

V (min)

ΔVR/ΔVIN

Input Reference Voltage Line

I1 = I2 = 0 mA and

0.003

%/V

Regulation

I1 = I2 = 1 mA ±1%

(4)

0.01/0.02

%/V (max)

IINV

Inverting Input Current

I1 = I2 = 0 mA, duty cycle = 25%

0.5

μA

Level Shift Accuracy

Level Shift Current = 1 mA

1.0

10/13

% (max)

ΔVR/Δt

Input Reference Voltage Long Term

100

ppm/1000h

Stability

OUTPUT

VC (sat)

Collector Saturation Voltage

IC = 750 mA pulsed, Emitter

0.7

grounded

0.90/1.2

V (max)

VE (sat)

Emitter Saturation Voltage

IO = 80 mA pulsed,

1.4

VIN = VC = 40V

1.7/2.0

V (max)

ICES

Collector Leakage Current

VIN = VCE = 40V, Emitter grounded,

0.1

μA

Output OFF

200/250

μA (max)

BVCEO(SUS)

Collector-Emitter Sustaining Voltage

ISUST = 0.2A (pulsed), VIN = 0

V (min)

CURRENT LIMIT

VCL

Sense Voltage Shutdown Level

Referred to VIN or Ground

110

See (5)

mV (min)

160

mV (max)

ΔVCL/ΔT

Sense Voltage Temperature Drift

0.3

%/°C

ICL

Sense Bias Current

Referred to VIN

4.0

μA

Referred to ground

0.4

μA

(1)

Typical values are for TJ = 25°C and represent the most likely parametric norm.

(2)

All limits specified at room temperature (standard type face) and at temperature extremes (bold type face). Room temperature limits are

100% production tested. Limits at temperature extremes are specified via correlation using standard Statistical Quality Control (SQC)

methods. All limits are used to calculate AOQL.

(3)

Input terminals are protected from accidental shorts to ground but if external voltages higher than the reference voltage are applied,

excessive current will flow and should be limited to less than 5 mA.

(4)

I1 and I2 are the external sink currents at the inputs (refer to Test Circuit).

(5)

Connection of a 10 k

Ω resistor from pin 1 to pin 4 will drive the duty cycle to its maximum, typically 90%. Applying the minimum Current

Limit Sense Voltage to pin 7 will not reduce the duty cycle to less than 50%. Applying the maximum Current Limit Sense Voltage to pin 7

is certain to reduce the duty cycle below 50%. Increasing this voltage by 15 mV may be required to reduce the duty cycle to 0%, when

the Collector output swing is 40V or greater (see Ground-Referred Current Limit Sense Voltage typical curve).

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