ML4812IQ Datasheet ML4812IQX, ML4812CP, ML4812CQ | P4-P6

PRODUCT SPECIFICATION ML4812

REV. 1.0.4 5/31/01

4

Electrical Characteristics

Unless otherwise speciﬁed, V

CC

= 15V , R

T

= 14k

Ω

, C

T

= 1000pF, T

A

= Operating Temperature Range (Notes 1, 2).

Parameter Conditions Min. Typ. Max. Units

Oscillator

Initial Accuracy T

J

= 25°C 91 98 105 kHz

Voltage Stability 12V < V

CC

< 18V 0.3 %

Temperature Stability 2 %

Total Variation Line, temperature 90 108 kHz

Ramp Valley to Peak 3.3 V

R

T

Voltage 4.8 5.0 5.2 V

Discharge Current (R

T

open) T

J

= 25°C, V

CT

= 2V 7.8 8.4 9.0 mA

V

CT

= 2V 7.3 8.4 9.3 mA

Clock Out Voltage Low RL = 16k

Ω

0.2 0.5 V

Clock Out Voltage High RL = 16k

Ω

3.0 3.5 V

Reference

Output Voltage T

J

= 25°C, I

O

= 1mA 4.95 5.00 5.05 V

Line Regulation 12V < V

CC

< 25V 2 20 mV

Load Regulation 1mA < IO < 20mA 2 20 mV

Temperature Stability 0.4 %

Total Variation Line, load, temp. 4.9 5.1 V

Output Noise Voltage 10Hz to 10kHz 50 µV

Long Term Stability T

J

= 125°C, 1000 hours 5 25 mV

Short Circuit Current V

REF

= 0V –30 –85 –180 mA

Error Amplifier

Input Offset Voltage ±15 mV

Input Bias Current –0.1 –1.0 µA

Open Loop Gain 1 < V

EA OUT

< 5V 60 75 dB

PSRR 12V < V

CC

< 25V 60 75 dB

Output Sink Current V

EA OUT

= 1.1V, V

EA–

= 6.2V 2 12 mA

Output Source Current V

EA OUT

= 5.0V, V

EA

– = 4.8V –0.5 –1.0 mA

Output High Voltage I

EA OUT

= –0.5mA, V

EA

– = 4.8V 5.3 5.5 V

Output Low Voltage I

EA OUT

= 1mA, V

EA

– = 6.2V 0.5 1.0 V

Unity Gain Bandwidth 1.0 MHz

Gain Modulator

I

SINE

Input Voltage I

SINE

= 500µA 0.4 0.7 0.9 V

Output Current (GM OUT) I

SINE

= 500µA, EA– = V

REF

– 20mV 430 470 510 µA

I

SINE

= 500µA, EA– = V

REF

+ 20mV 3 10 µA

I

SINE

= 1mA, EA– = V

REF

– 20mV 860 940 1020 µA

I

SINE

= 500µA, EA– = V

REF

– 20mV,

I

RAMP COMP

= 50µA

455 µA

Bandwidth 200 kHz

PSRR 12V < V

CC

< 25V 70 dB

ML4812 PRODUCT SPECIFICATION

5

REV. 1.0.4 5/31/01

Notes:

1. Limits are guaranteed by 100% testing, sampling, or correlation with worst-case test conditions.

2. V

CC

is raised above the Startup Threshold first to activate the IC, then returned to 15V.

OVP Comparator

Input Offset Voltage Output Off –25 +5 mV

Hysteresis Output On 95 105 115 mV

Input Bias Current –0.3 –3µA

Propagation Delay 150 ns

PWM Comparator: I

SENSE

Input Offset Voltage ±15 mV

Input Offset Current ±1 µA

Input Common Mode Range –0.2 5.5 V

Input Bias Current –2 –10 µA

Propagation Delay 150 ns

I

LIMIT

Trip Point V

GM OUT

= 5.5V 4.8 5 5.2 V

Output

Output Voltage Low I

OUT

= –20mA 0.1 0.4 V

I

OUT

= –200mA 1.6 2.2 V

Output Voltage High I

OUT

= 20mA 13 13.5 V

I

OUT

= 200mA 12 13.4 V

Output Voltage Low in UVLO I

OUT

= –5mA, V

CC

= 8V 0.1 0.8 V

Output Rise/Fall Time C

L

= 1000pF 50 ns

Shutdown V

IH

2.0 V

V

IL

0.8 V

I

IL

, V

SHDN

= 0V –1.5 mA

IIH, V

SHDN

= 5V 10 µA

Under-Voltage Lockout

Startup Threshold 15 16 17 V

Shutdown Threshold 9 10 11 V

V

REF

Good Threshold 4.4 V

Supply

Supply Current Start-Up, V

CC

= 14V, T

J

= 25°C 0.8 1.2 mA

Operating, T

J

= 25°C2025mA

Internal Shunt Zener Voltage I

CC

= 30mA 25 30 34 V

Electrical Characteristics

(Continued)

Unless otherwise speciﬁed, V

CC

= 15V , R

T

= 14k

Ω

, C

T

= 1000pF, T

A

= Operating Temperature Range (Notes 1, 2).

Parameter Conditions Min. Typ. Max. Units

ML4812 PRODUCT SPECIFICATION

6

REV. 1.0.4 5/31/01

Functional Description

Oscillator

The ML4812 oscillator charges the external capacitor (C

T

)

with a current (I

SET

) equal to 5/R

SET

. When the capacitor

voltage reaches the upper threshold, the comparator changes

state and the capacitor discharges to the lower threshold

through Q1. While the capacitor is discharging, Q2 provides

a high pulse.

The Oscillator period can be described by the following

relationship:

where:

and:

T

OSC

T

RAMP

T

DEADTIME

+=

V

OUT

V

IN

1D

ON

–

--------------------=

T

DEADTIME

C

T

V

RAMPVALLEYTOPEAK

×

8.4mA I

SET

–

-------------------------------------------------------------------------=

Figure 1. Oscillator Block Diagram

Figure 2. Oscillator Timing Resistance vs. Frequency

Figure 3. Output Saturation Voltage vs. Output Current

10

SYNC

Q

2

Q

1

9

R

T

16

C

T

EXTERNAL

CLOCK

+

-

5.6V

I

SET

8.4mA

C

T

R

T

I

SET

C

SYNC

R

SYNC

CLOCK

t

D

RAMP VALLEY

RAMP PEAK

V(C

T

)

10

R

T

(kΩ)

OSCILLATOR FREQUENCY (kHz)

10 100 1000

8

5

3

2

1

MAXIMUM DUTY CYCLE (%)

10nF

20nF

5nF 2nF

1nF

85%

80%

70%

90%

15

14

13

3

2

1

0

OUTPUT SATURATION VOLTAGE (V)

OUTPUT CURRENT (mA)

0 200 400 800

600

V

CC

V

CC

= 15V

80µs PULSED LOAD

120Hz RATE

GND

SOURCE SATURATION

LOAD TO GROUND

SINK SATURATION

LOAD TO V

CC

ML4812IQ

ML4812IQ

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