Datasheet ML4835CS, ML4835CP Datasheet (Micro Linear Corporation)

July 2000

PRELIMINARY

ML4835*

Compact Fluorescent Electronic Dimming

Ballast Controller

GENERAL DESCRIPTION

The ML4835 is a complete solution for a dimmable or a
non-dimmable, high power factor, high efficiency
electronic ballast especially tailored for a compact
fluorescent lamp (CFL). The Bi-CMOS ML4835 contains
controllers for “boost” type power factor correction as
well as for a dimming ballast with end-of-lamp life
detection.

The PFC circuits uses a new , simple PFC topology which
requires only one loop for compensation. In addition,
this PFC can be used with either peak- or average-current
mode. This system produces a power factor of better than

0.99 with low input current THD.

The ballast controller section provides for programmable
starting sequence with individual adjustable preheat and
lamp out-of-socket interrupt times. The ML4835 provides
a shut down for both PFC and ballast controllers in the
event of end-of-life for the CFL.

FEATURES

■ Power detect for end-of-lamp-life detection

■ Low distortion , high efficiency continuous boost, peak

or average current sensing PFC section

■ Leading- and trailing-edge synchronization between

PFC and ballast

■ One to one frequency operation between PFC and

ballast

■ Programmable start scenario for rapid/instant start lamps

■ Triple frequency control network for dimming or

starting to handle various lamp sizes

■ Programmable restart for lamp out condition to reduce

ballast heating.

■ Internal over-temperature shutdown

■ PFC over-voltage comparator eliminates output

“runaway” due to load removal

■ Low start-up current; < 0.55mA

(* Indicates Part is End Of Life as of July 1, 2000)

BLOCK DIAGRAM

C

RAMP

13

PIFBO

4

PIFB

3

PEAO

2

PVFB/OVP

1

R

SET

7

RT/C

T

9

R

T2

8

PWDET

12

POWER

FACTOR

CONTROLLER

VARIABLE FREQUENCY

OSCILLATOR

THREE-FREQUENCY

CONTROL SEQUENCER

VCO

END-OF-LAMP DETECT

AND

POWER SHUTOFF

ANTI-FLASH

COMPENSATION

POWER DIMMING LEVEL

AND

INTERFACE

UNDER-VOLTAGE

AND

THERMAL SHUTDOWN

AGND

REF

20

14

INTERRUPT

CONTROL

AND

GATING

LOGIC

OUTPUT
DRIVERS

PRE-HEAT AND

INTERRUPT TIMERS

LAMP OUT DETECT

AND

AUTOMATIC LAMP

RESTART

V

CC

19

LAMP FB

PFC OUT

LEAO

OUT A

OUT B

PGND

RX/C

10

5

6

17

16

18

15

X

11

1

ML4835

PIN CONFIGURATION

PIN DESCRIPTION

PVFB/OVP

PEAO

PIFB

PIFBO

LAMP FB

LEAO

R

SET

R

RT/C

INTERRUPT

20-Pin SOIC (S20)

20-Pin DIP (P20)

1

2

3

4

5

6

7

8

T2

9

T

10

ML4835

20

REF

19

V

CC

18

PFC OUT

17

OUT A

16

OUT B

15

PGND

14

AGND

13

C

RAMP

12

PWDET

11

RX/C

X

PIN NAME FUNCTION

1 PVFB/OVP Inverting input to the PFC error

amplifier and OVP comparator input.

2 PEAO PFC error amplifier output and

compensation node

3 PIFB Senses the inductor current and peak

current sense point of the PFC cycle
by cycle current limit

4 PIFBO Output of the current sense amplifier.

Placing a capacitor to ground will
average the inductor current.

5 LAMP FB Inverting input of the lamp error

amplifier, used to sense and regulate
lamp arc current. Also the input node
for dimmable control.

6 LEAO Output of the lamp current error

transconductance amplifier used for
lamp current loop compensation

7R

8R

SET

T2

External resistor which SETS oscillator
F

, and RX/CX charging current

MAX

Oscillator timing component to set
start frequency

PIN NAME FUNCTION

10 INTERRUPT Input used for lamp-out detection and

restart. A voltage less than 1V will
reset the IC and cause a restart after a
programmable interval.

11 RX/C

X

Sets the timing for preheat and
interrupt.

12 PWDET Lamp output power detection

13 C

RAMP

Integrated voltage of the error
amplifier out

14 AGND Analog ground

15 PGND Power ground.

16 OUT B Ballast MOSFET driver output

17 OUT A Ballast MOSFET driver output

18 PFC OUT Power factor MOSFET driver output

19 V

CC

Positive supply voltage

20 REF Buffered output for the 7.5V reference

9RT/C

2

T

Oscillator timing components

ABSOLUTE MAXIMUM RATINGS

ML4835

Absolute maximum ratings are those values beyond which
the device could be permanently damaged. Absolute
maximum ratings are stress ratings only and functional
device operation is not implied.

Junction Temperature .............................................. 150ºC

Storage Temperature Range ...................... –65ºC to 150ºC

Lead Temperature (Soldering, 10 sec) ..................... 260ºC

Thermal Resistance (qJA)

ML4835CP .......................................................... 65ºC/W

Supply Current (I

............................................................. 65mA

CC)

ML4835CS .......................................................... 80ºC/W

Output Current, Source or Sink

(OUT A, OUT B, PFC OUT) DC ........................... 250mA

OPERATING CONDITIONS

PIFB Input Voltage ............................................–3V to 2V

Maximum Forced Voltage

Temperature Range ....................................... 0°C to 85°C

(PEAO, LEAO)............................................–0.3V to 7.7V

Maximum Forced Current

(PEAO, LEAO)...................................................... ±20mA

ELECTRICAL CHARACTERISTICS

Unless otherwise specified, VCC = V
TA = Operating Temperature Range (Note 1)

SYMBOL PARAMETER CONDITIONS MIN TYP MAX UNITS

LAMP CURRENT AMPLIFIER (LAMP FB, LEAO)

Input Bias Current -0.3 -1.0 µA

Small Signal Transconductance 35 75 105 µ

CCZ

–0.5V, R

= 11.8kW, RT = 15.4kW, RT2 = 67.5kW, CT = 1.5nF,

SET

W

Input Bias Voltage -0.3 5.0 V

Output Low LAMP FB = 3V, RL = ¥ 0.2 0.4 V

Output High LAMP FB = 2V, RL = ¥ 7.1 7.5 V

Source Current LAMP FB = 0V, LEAO = 6V -80 -220 µA

Sink Current LAMP FB = 5V, LEAO = 0.3V 80 220 µA

PFC VOLTAGE FEEDBACK AMPLIFIER ( PEAO, PVFB/OVP)

Input Bias Current -0.3 -1.0 µA

Small Signal Transconductance 35 75 105 µ

Input Bias Voltage -0.3 5.0 V

Output Low PVFB = 3V, RL = ¥ 0.2 0.4 V

Output High PVFB = 2V, RL = ¥ 6.4 6.8 V

Source Current PVFB = 0V, PEAO = 6V -80 220 µA

Sink Current PVFB = 5V, PEAO = 0.3V 80 220 µA

PFC CURRENT-LIMIT COMPARATOR (PIFB)

Current-Limit Threshold -0.9 -1.0 -1.1 V

Propagation Delay 100mV Step and 100mV Overdrive 100 ns

PFC OVP COMPARATOR

W

OVP Threshold 2.65 2.75 2.85 V

Hysteresis 0.14 0.20 0.30 V

Propagation Delay 1.4 µs

3

ML4835

ELECTRICAL CHARACTERISTICS (Continued)

SYMBOL PARAMETER CONDITIONS MIN TYP MAX UNITS

OSCILLATOR

Initial Accuracy (F

Voltage Stability (F

Temperature Stability (F

Total Variation (F

Initial Accuracy (START) TA = 25ºC 49 50 51 kHz

Voltage Stability (START) 0.3 %

Temparature Stability (START) 0.3 %

Total Variation (START) Line, Temperature 49 51 kHz

Ramp Valley to Peak 2.5 V

Initial Accuracy (Preheat) TA = 25ºC 60.8 64 67.2 kHz

Total Variation (Preheat) Line, Temperature 60.8 64 67.2 kHz

CT Discharge Current V

Output Drive Deadtime CT = 1.5nF 0.7 us

REFERENCE BUFFER

Output Voltage TA = 25ºC, IO = 0mA 7.4 7.5 7.6 V

Line Regulation V

Load Regulation 1mA < IO < 10mA 2 15 mV

)T

MIN

)V

MIN

) 0.3 %

MIN

) Line, Temperature 39.2 40.8 kHz

MIN

= 25ºC 39.2 40 40.8 kHz

A

– 4V < V

CCZ

= 2.5V 6.0 7.5 9.0 mA

RTCT

– 4V < V

CCZ

CC

CC

< V

< V

– 0.5V 0.3 %

CCZ

– 0.5V 10 25 mV

CCZ

Temperature Stability 0.4 %

Total Variation Line, Load, Temperature 7.35 7.65 V

Long Term Stabilty Tj=125ºC, 1000 hrs 5 mV

Short Circuit Current 40 mA

R

Voltage 2.4 2.5 2.6 V

SET

4

ML4835

ELECTRICAL CHARACTERISTICS (Continued)

SYMBOL PARAMETER CONDITIONS MIN TYP MAX UNITS

PREHEAT AND INTERRUPT TIMER (RX = 346kW, CX = 10µF)

Initial Preheat Period 0.86 s

Subsequenct Preheat Period 0.72 s

Interrupt Period 5.9 s

RX/CX Charging Current -50 -54 -58 µA

RX/CX Open Circuit Voltage 0.4 0.7 1.0 V

RX/CX Maximum Voltage 7.0 7.3 7.8 V

Preheat Lower Threshold 1.6 1.75 1.9 V

Preheat Upper Threshold 4.4 4.65 4.9 V

Start Period End Threshold 6.2 6.6 6.9 V

Interrupt Disable Threshold 1.1 1.25 1.4 V

Hysteresis 0.16 0.26 0.36 V

Input Bias Current 1µA

POWER SHUTDOWN

Power Shutdown Voltage 0.9 1 1.1 V

OUTPUTS (OUT A, OUT B, PFC OUT)

Output Voltage Low I

Output Voltage High I

Output Voltage High I

Output Voltage Low in UVLO I

Output Rise and Fall Time CL=1000pF 50 ns

UNDER VOLTAGE LOCKOUT AND BIAS CIRCUITS

IC Shunt Voltage (V

Start-up Threshold (V

) ICC=15mA 14.0 14.8 15.5 V

CCZ

CC START

)V

Hysteresis 3.0 3.7 4.4 V

Start-up Current V

Interrupt Current (VCC–0.5V), INTERRUPT = 0V 500 750 µA

Operating Current (VCC–0.5V) 5.5 8.0 mA

Shutdown Temperature 130 ºC

Hysteresis 30 ºC

= 20mA 0.1 0.2 V

OUT

I

= 200mA 1.0 2.0 V

OUT

= 20mA VCC-0.2 VCC-0.1 V

OUT

= 200mA VCC-2.0 VCC-1.0 V

OUT

= 10mA, VCC < V

OUT

CC START

–0.2V 350 550 µA

CC START

CCZ

-1.5 V

CCZ

-1.0 V

CCZ

0.2 V

-0.5 V

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

5

ML4835

FUNCTIONAL DESCRIPTION

The ML4835 consists of peak or average current
controlled continuous boost power factor front end section
with a flexible ballast control section. Start-up and lamp­out retry timing are controlled by the selection of external
timing components, allowing for control of a wide variety
of different lamp types. The ballast section controls the
lamp power using frequency modulation (FM) with
additional programmability provided to adjust the VCO
frequency range. This allows for the IC to be used with a
variety of different output networks. Figure 1 depicts a
detailed block diagram of ML4835.

The ML4835 provides several safety features. See the
corresponding sections for more details:

REF

20

V

CC

19

AGND

14

14V

C

RAMP

13

PVFB/OVP

1

2.5V

PEAO

2

PIFBO

4

PIFB

3

PFC OUT

18

2.75V

PVFB

RX/C

11

R

SET

7

X

–1V

6.75V

REF

–
+

UVLO

–

+

+

–

ILIM

+

–

OVP

REF_OK

+

–

V

TO

I

+

–

RSQ

RSQ

Q

PFC CONTROLLER

THERMAL SHUTDOWN

4.75V/

1.75V

Q

• End-of-lamp life detection to detect EOL and shut-off
lamps; See End Of Life Section.

• Thermal shutdown for temperature sensing extremes;
See IC Bias, Under-Voltage Lockout and Thermal
Shutdown Section.

• Relamping starting with anti-flash for programmable
restart for lamp out conditions while minimizing
“flashing” when powering from full power to dimming
levels; See Starting, Re-Start, Preheat and Interrupt
Section

TEMP

+

130ºC/100ºC

–

QQR

S

COMP

1.25V/1V

+
–

–
+

RX/C

CLK1

PREHEAT

+

–

QQS

R

Q

T

Q

÷2

CLK

OSCILLATOR

TO

V

I

TO

V

I

OUT A

OUT B

PGND

PWDET

+

–

1.0V

INTERRUPT

X

6.75V/1.25V

RT

RT/C

LEAO

LAMP FB

–

2.5V

+

17

16

15

12

10

2

8

T

9

6

5

Figure 1. Detailed Block Diagram

6

FUNCTIONAL DESCRIPTION (Continued)

ML4835

The ML4835 implements a triple frequency operation
scheme: programmable three-frequency sequence for pre­heat, ignition, and dimming, that extends lamp life,
simplifies lamp network design, and starts lamps at any
dimming level without flashing. This addresses the need
for a high-Q network for starting sequence and low-Q
network for operation, minimizing parasitic losses and
improving overall power efficiency. The values for the
pre-heat, start, operation, and restart can be programmed
or selected (Figure 2).

SET TIME VALUES

FOR PREHEAT,

START AND OPERATION,

AND RESTART

ML4835

POWER FACTOR SECTION

The ML4835 power factor section is a peak or average
current sensing boost mode PFC control circuit in which
only voltage loop compensation is needed. It is simpler
than a conventional average current control method. It
consists of a voltage error amplifier, a current sense
amplifier (no compensation is needed), an integrator, a
comparator, and a logic control block. In the boost
topology, power factor correction is achieved by sensing
the output voltage and the current flowing through the
current sense resistor. Duty cycle control is achieved by
comparing the integrated voltage signal of the error
amplifier and the voltage across R

. The duty cycle

SENSE

control timing is shown in Figure 3.

PREHEAT

f

1

HIGH Q

LOW Q

f

3

OPERATION

START

f

2

CLK

PFC OUT

RAMP

EMI

FILTER

PIFBO

Figure 2. Three Frequency Design Model

L

R

SENSE

PIFB PIFBO

–A

V

RA

RB

VREF1

OUT

INVERTER

PVFB/OVP

LAMP

NETWORK

1

LAMP

LAMP

SW2

SW1

C

C

RAMP

RAMP

183

PFC OUT

+

–

OSC

V TO I

RQ

S

PEAO

PEAO

2

R1

C1

CLK

–

+

C2

4

13

Figure 3. ML4835 PFC Controller Section

7

ML4835

FUNCTIONAL DESCRIPTION (Continued)

Setting minimum input voltage for output regulation can
be achieved by selecting C

as follows for peak

RAMP

current mode:

PEAO

C

RAMP

MAX

=--

DTs t

1

()

:?

K

22

D



PVVV

22

OUTINOUT IN

-

!

1



-



L

2



"



-

DTs R

18

()

#




#

$

´

SENSE

(1)

And for average current mode:

PEAO

MAX

DTs t

1

C

=--

RAMP

()

:?

K

22

D



PVV

2

OUTINOUT

!

1

"





-




DTs R

18

()

-

´

#



L

2



#

$

SENSE

(1a)

Where Dt is the dead time.

POWER DETECT

POWER LEVEL

TRIP POINT

ML4835

OVERVOLTAGE PROTECTION AND INHIBIT

The OVP pin serves to protect the power circuit from
being subjected to excessive voltages if the load should
change suddenly (lamp removal). A divider from the high
voltage DC bus sets the OVP trip level. When the voltage
on PVFB/OVP exceeds 2.75V, the PFC transistor are
inhibited. The ballast section will continue to operate.

TRANSCONDUCTANCE AMPLIFIERS

The PFC voltage feedback amplifier is implemented as an
operational transconductance amplifier. It is designed to
have low small signal forward transconductance such that
a large value of load resistor (R1) and a low value
ceramic capacitor (<1µF) can be used for AC coupling

CURRENT

MIRROR

IN OUT

gmV

IN

2

io = gmV

IN

IQ –

gmV

IQ +

IN

2

POWER SHUTOFF

Figure 4. Simplified Model of ML4835 EOL Functionality

PVFB/OVP

1

2.5V

–

+

R1

C1

C2

IN OUT

CURRENT

MIRROR

Figure 6. Output Configuration

i

O

0

LINEAR SLOPE REGION

VIN DIFFERENTIAL

Figure 5. Compensation Network

Figure 7. Transconductance Amplifier Characteristics

8

REF

20

ML4835

R

T2

8

INTERRUPT

10

1.25/1.0V

V

CC

19

RX/C

11

4.75/1.25V

LEA_ENB

X

R

T2

–

+

0.625
R

SET

–

+

7.5V

DURING PREHEAT

I

R

T

RT/C

9

C

+

T

NOTE 1: R

I

CHG

T

3.75/1.25V

5.5mA

SHOULD BE SELECTED SUCH THAT AFTER PREHEAT WITH LEA_ENB "HI",

SET

I

MUST BE < 0.

CHG

IS A UNI-DIRECTIONAL SOURCE CURRENT ONLY.

I

CHG

+

–

AFTER PREHEAT
LEA_ENB = HI

I

LEA_ENB = LOW

I

CHG

CHG

CHG

2.5V

=

RSET

5V

5V

7.5V

–

8K±25%

LEAO

–

8K±25%

=

RSET

=

RSET

CLOCK

t

VTH = 3.75V

C

T

VTL = 1.25V

DIS t

CHG

Figure 8. Oscillator Block Diagram and Timing

VCCZ

V

CC

V(ON)

V(OFF)

I

CC

5.5mA

t

0.34mA

t

Figure 9. Typical VCC and ICC Waveforms when the ML4835 is Started with a Bleed Resistor from

the Rectified AC Line and Bootstrapped from an Auxiliary Winding.

9

ML4835

FUNCTIONAL DESCRIPTION (Continued)

(C1) in the frequency compensation network. The
compensation network shown in Figure 5 will introduce a
zero and a pole at:

f

ZP

Figure 4 shows the output configuration for the
operational transconductance amplifiers.

A DC path to ground or VCC at the output of the
transconductance amplifiers will introduce an offset error.
The magnitude of the offset voltage that will appear at the
input is given by VOS = io/gm. For an io of 1µA and a gm
of 0.05 µW the input referred offset will be 20mV.
Capacitor C1 as shown in Figure 5 is used to block the
DC current to minimize the adverse effect of offsets.

Slew rate enhancement is incorporated into all of the
operational transconductance amplifiers in the ML4835.
This improves the recovery of the circuit in response to
power up and transient conditions. The response to large
signals will be somewhat non-linear as the
transconductance amplifiers change from their low to
high transconductance mode, as illustrated in Figure 7.

END OF LAMP LIFE

At the end of a lamp’s life when the emissive material is
depleted, the arc current is rectified and high voltage
occurs across the lamp near the depleted cathode. The
ballast acts as a constant current source so power is
dissipated near the depleted cathode which can lead to
arcing and bulb cracking. Compact fluorescent lamps are
more prone to cracking or shattering because their small
diameter can’t dissipate as much heat as the larger linear
lamps. Compact fluorescents also present more of a
safety hazard since they are usually used in downlighting
systems without reflector covers.

EOL and the ML4835

The ML4835 uses a circuit that creates a DC voltage
representative of the power supplied to the lamps through
the inverter. This voltage is used by the ML4835 to latch
off the ballast when it exceeds an internal threshold. An
external resistor can be used as the “EOL latch resistor” to
set the power level trip point, as shown in by R9 in Figure

12. See Micro Linear ML4835 User Guide and
applications notes for more details. Figure 4 illustrates a
simplified model of ML4835 EOL functionality.

BALLAST OUTPUT SECTION

1

==

RC

2

pp

11 12

f

1

RC

2

(2)

OSCILLATOR

The VCO frequency ranges are controlled by the output
of the LFB amplifier (R
LFB OUT falls in voltage, causing the CT charging current
to increase, thereby causing the oscillator frequency to
increase. Since the ballast output network attenuates high
frequencies, the power to the lamp will be decreased. The
oscillator frequency is determined by the following
equations:

F

=

OSC

and

tRCIn

CHG T T

The oscillator’s minimum frequency is set when I
where:

F

@

MIN

The oscillator's start frequency can be expressed by:

F

START

Both equations assume that t

When LFB OUT is high, I
frequency occurs. The charging current varies according
to two control inputs to the oscillator:

1. The output of the preheat timer

2. The voltage at LFB OUT (lamp feedback amplifier
output)

In preheat condition, charging current is fixed at

I

CHG PREHEAT

()

In running mode, charging current decreases as the
voltage rises from 0V to VOH at the LAMP FB amplifier.

The charging current behavior can be expressed as:

I

=

CHG

1

+

tt

CHG DIS

=

1

´

RC

051.

=

´´

0512.

=

V

5

-

R

SET

8 25%

). As lamp current decreases,

SET



+´-

VI RV

REF CHG T TL



VII RV

+´-



REF CHG T TH

TT

1

RR C

27

TT T

>> t

.

25

R

SET

LEAO

±

k

CHG

= 0 and the minimum

CHG

DIS






CHG

.

(3)

(4)

= 0

(5)

(5a)

(6)

(7)

The IC controls output power to the lamps via frequency
modulation with non-overlapping conduction. This means
that both ballast output drivers will be low during the
discharging time t

of the oscillator capacitor CT.

DIS

10

The highest frequency is attained when I
which is attained when voltage at LFB OUT is at 0V:

()0

=

5

R

SET

I

CHG

is highest,

CHG

(8)

/

FUNCTIONAL DESCRIPTION (Continued)

ML4835

Highest lamp power, and lowest output frequency are
attained when voltage at LFB OUT is at its maximum
output voltage (VOH).

In this condition, the minimum operating frequency of the
ballast is set per equation 5 above.

For the IC to be used effectively in dimming ballasts with
higher Q output networks a larger CT value and lower R

T

value can be used, to yield a smaller frequency excursion
over the control range (voltage at LFB OUT). The
discharge current is set to 5.5mA.

Assuming that I

tC

DIS VCO T()

>>IRT:

DIS

@´

600

(9)

IC BIAS, UNDER-VOLTAGE LOCKOUT AND
THERMAL SHUTDOWN

The IC includes a shunt clamp which will limit the
voltage at VCC to 15V (V

). The IC should be fed with

CCZ

a current limited source, typically derived from the
ballast transformer auxiliary winding. When VCC is below
V

– 1.1V, the IC draws less than 0.55mA of quiescent

CCZ

current and the outputs are off. This allows the IC to start
using a “bleed resistor” from the rectified AC line.

To help reduce ballast cost, the ML4835 includes a
temperature sensor which will inhibit ballast operation if
the IC’s junction temperature exceeds 130°C. In order to
use this sensor in lieu of an external sensor, care should
be taken when placing the IC to ensure that it is sensing
temperature at the physically appropriate point in the
ballast. The ML4835’s die temperature can be estimated
with the following equation:

TT P CW

@+ +°

JA D

(

)65

(10)

STARTING, RE-START, PREHEAT AND INTERRUPT

The circuit in Figure 10 controls the lamp starting
scenarios: Filament preheat and lamp out interrupt. CX is
charged with a current of I

/4 and discharged through

R(SET)

RX. The voltage at CX is initialized to 0.7V (VBE) at power
up. The time for CX to rise to 4.75V is the filament preheat
time. During that time, the oscillator charging current
(I

CHG

) is 2.5/R

. This will produce a high frequency for

SET

filament preheat, but will not produce sufficient voltage
to ignite the lamp or cause significant glow current.

After cathode heating, the inverter frequency drops to
F

causing a high voltage to appear to ignite the

START

lamp. If lamp current is not detected when the lamp is
supposed to have ignited, the CX charging current is shut
off and the inverter is inhibited until CX is discharged by
RX to the 1.25V threshold. Shutting off the inverter in this
manner prevents the inverter from generating excessive
heat when the lamp fails to strike or is out of socket.
Typically this time is set to be fairly long by choosing a
large value of RX.

LFB OUT is ignored by the oscillator until INTERRUPT is
above 1.25V The CX pin is clamped to about 7.5V.

Care should also be taken not to turn on the VCCZ clamp
so as not to dissipate excessive power in the IC. This will
cause the temp sensor to become active at a lower
ambient temperature.

A summary of the operating frequencies in the various
operating modes is shown below.

OPERATING MODE OPERATING FREQUENCY

Preheat

After

Preheat

Dimming

Control

[F(MAX) to F(MIN)]

2

F(START)

F(MIN) to F(MAX)

The lamp starting scenario implemented in the ML4835
is designed to maximize lamp life and minimize ballast
heating during lamp out conditions.

0.625
R

SET

R

X/CX

10

R

X

C

INTERRUPT

9

X

1.25/4.75

1.0/1.25

1.25/6.75

Figure 10. Lamp Preheat and Interrupt Timers

+

–

+

–

+

–

HEAT

LEA_ENB OR
DIMMING LOCKOUT

SRQ

INHIBIT

11

ML4835

TYPICAL APPLICATIONS

The ML4835 can be used for a variety of lamp types:

T4 or compact fluorescent lamps
IEC T8 (linear lamps)
T5 linear lamps
T12 linear lamps

6.75

R

4.75

X/CX

1.25
.7

0

The ML4835 can also be used for dimming applications.
For example, 20:1 dimming can be achieved using the
ML4835 with external dimming units. The applications
schematics shown in Figures 12, 13, and 14 are examples
of the various uses of the ML4835.

7.5

HEAT

LEA_ENB OR

DIMMING LOCKOUT

INTERRUPT

INHIBIT

Figure11. Lamp Starting and Restart Timing

12

ML4835

HOT

120V

RMS

NEUTRAL

C29

100pF

C17

8.2nF

610

T1

D10, 0.1A

75V

C5

0.1µF

C6

0.1µF

1

2

3

4

5

6

7

8

9

10

C22

1.5µF

R4, 62kΩ

D8, 1A, 600V

89

D9, 0.1A
75V

D14

0.1A
75V

820Ω
R19, 16.2kΩ

R21, 51.1kΩ

U1

PVFB

PEAO

PIFB

PIFBO

LFB

LEAO

RSET

RT2

RT/CT

INTRPT

R23, 200kΩ

R22

360kΩ

100µF

R3

ML4835

C7

V

PFC OUT

OUT A

OUT B

P GND

A GND

RAMP

PW DET

RX/CX

1A, 600V

(ULTRA-

FAST)

Q1

4.5A, 500V

D11, 15V, 0.5W

20

REF

19

CC

18

17

16

15

14

13

12

11

C21
15µF

D7

R6
432kΩ

D18

0.1A

C24
470pF

75V

R25
100Ω

C27

0.22µF

R7
432kΩ

R8

5.76kΩ

R9

4.3Ω

R24

20kΩ

C25

0.22µF

C8
47µF

C23

6.8µF

R10
30Ω

C9
1µF

6

7

D16, 0.1A, 75V

3

2

D17, 0.1A, 75V

1

8

C26
47µF

R16

10kΩ

R11

150Ω

R12

150Ω

2.5A, 500V

2.5A, 500V

D13

5.6V, 0.5W

C11
6800pF

D12

0.1A, 75V

T3

6

7

4

C30
120pF

3

2

C28
120pF

1

9

8

51

T3

610

R
R
Y
Y
B
B

Q2

C12

0.33µF

D19

1A

C15
1µF

600V

D15

600V

1A

R14

22.6kΩ

C14

0.015µF

R13
1kΩ

Q3

L1

3.3nF

3.3nF

0.33Ω

C1

C2

R1

D1-D4: 1A, 600V

C3

0.15µF

D5
1A, 50V

100Ω

D6
1A, 50V

D1

D3

D4

D2

R2

F1

L2

R15, 681kΩ

C16

82nF

33nF

C18

R26

1.5nF

5kΩ

R17

R18

4.3kΩ

C20

1.5nF

C19
1µF

C4

8.06kΩ

DIMMER INTERFACE ASSEMBLY

R8

D1

100µF

180Ω

D2

C1

18V

0.1A, 75V

T1

3

4

10µF

3.32kΩ

R6

1MΩ

Q1

C4

R7

3.32kΩ

R3

16.2kΩ

R5

R4

220kΩ

C2

D3

220pF

C3, 1nF

8

3

+

2

–

5

+

6

–

4

U2A

U2B

R2

1.5kΩ

1

1

2

7

U1

0.01µF

R1
604Ω

5

4

C5

VIOLET
GREY

MANUAL DIMMER

0-10VDC

Figure12. Ballast for Architectural Dimming Applications

13

ML4835

HOT

120V

RMS

NEUTRAL

C29

100pF

C17

8.2nF
C20

R4, 62kΩ

D8, 1A, 600V

610

T1

D10, 0.1A

75V

C5

0.1µF

C6

0.1µF

1

2

3

4

5

6

7

8

9

10

C22

1.5µF

89

R19, 16.2kΩ

R21, 51.1kΩ

U1

PVFB

PEAO

PIFB

PIFBO

LFB

LEAO

RSET

RT2

RT/CT

INTRPT

360kΩ

D9, 0.1A
75V

100µF

D14

0.1A
75V

R3

820Ω

ML4835

R23, 200kΩ

R22

C7

V

PFC OUT

OUT A

OUT B

P GND

A GND

RAMP

PW DET

RX/CX

1A, 600V

(ULTRA-

FAST)

Q1

4.5A, 500V

D11, 15V, 0.5W

20

REF

19

CC

18

17

16

15

14

13

12

11

C21
15µF

D7

R6
432kΩ

D18

0.1A
75V

C24
470pF

R25
100Ω

C27

0.22µF

R7
432kΩ

R8

5.76kΩ

R9

4.3Ω

R24

20kΩ

C25

0.22µF

C8
47µF

C23

6.8µF

R10
30Ω

C9
1µF

6

7

C26
47µF

D16, 0.1A, 75V

R11

3

150Ω

2

2.5A, 500V

D17, 0.1A, 75V

R12

1

150Ω

8

2.5A, 500V

R16

10kΩ

Q2

Q3

D13

5.6V, 0.5W

C15
1µF

L3

D19
1A
600V

D15
1A
600V

R14

22.6kΩ

C12

0.33µF

C11
6800pF

C14

0.015µF

R13
1kΩ

C13

2700pF

T3

4

C30
120pF

3

C10

0.33µF

6

7

D12

0.1A, 75V

2

C28
120pF

1

9

8

51

T3

610

6

8

10

R
R
Y
Y
B
B

L1

3.3nF

3.3nF

0.33Ω

C1

C2

R1

D1-D4: 1A, 600V

C3

0.15µF

D5
1A, 50V

100Ω

D6
1A, 50V

D1

D3

D4

D2

R2

F1

L2

R15, 681kΩ

C16

82nF

33nF

C18

R26

1.5nF

5kΩ

R17

R18

4.3kΩ

1.5nF

C19
1µF

C4

8.06kΩ

14

DIMMER INTERFACE ASSEMBLY

R8

D1

100µF

180Ω

D2

C1

18V

0.1A, 75V

T1

3

4

10µF

3.32kΩ

R6

1MΩ

Q1

C4

R7

3.32kΩ

R3

16.2kΩ

R5

R4

220kΩ

C2

D3

220pF

C3, 1nF

8

3

+

2

–

5

+

6

–

4

U2A

U2B

R2

1.5kΩ

1

1

2

7

U1

0.01µF

R1
604Ω

5

4

C5

VIOLET
GREY

MANUAL DIMMER

0-10VDC

Figure13. Ballast for Architectural Downlighting Applications

ML4835

HOT

120V

RMS

NEUTRAL

C29

100pF

C17

8.2nF

L1

C16

82nF

3.3nF

3.3nF

0.33Ω

D1-D4: 1A, 600V

C1

C2

R1

R15, 681kΩ

C4

33nF

C3

0.15µF

C18

1.5nF

D5
1A, 50V

D6
1A, 50V

R26

5kΩ

R18

8.06kΩ

D3

D4

100Ω

D1

D2

R2

C20

1.5nF

F1

L2

R4, 62kΩ

D8, 1A, 600V

610

T1

D10, 0.1A

75V

C5

0.1µF

C6

0.1µF

1

2

3

4

5

6

7

8

9

10

C22

1.5µF

89

D14

0.1A
75V

R19, 16.2kΩ

R21, 51.1kΩ

U1

PVFB

PEAO

PIFB

PIFBO

LFB

LEAO

RSET

RT2

RT/CT

INTRPT

360kΩ

D9, 0.1A
75V

100µF

R3

820Ω

ML4835

R23, 200kΩ

R22

C7

V

PFC OUT

OUT A

OUT B

P GND

A GND

RAMP

PW DET

RX/CX

1A, 600V

Q1

4.5A, 500V

D11, 15V, 0.5W

20

REF

19

CC

18

17

16

15

14

13

12

11

C21
15µF

D7

R6
432kΩ

D18

0.1A
75V

C24
470pF

R25
100Ω

C27

0.22µF

R7
432kΩ

R8

5.76kΩ

R9

4.3Ω

R24

20kΩ

C25

0.22µF

C8
47µF

C23

6.8µF

R10
30Ω

C9
1µF

6

7

C26
47µF

D16, 0.1A, 75V

R11

3

150Ω

2

2.5A, 500V

D17, 0.1A, 75V

R12

1

150Ω

8

Q2

2.5A, 500V

C11
6800pF

T3

6

7

4

C30
120pF

3

2

C28
120pF

1

9

8

51

T3

610

R
R
Y
Y
B
B

C12

0.33µF

D19

1A

R13

1kΩ

600V

D15

1A

600V

D12

0.1A, 75V

C14

0.015µF

Q3

Figure14. Non-Dimming Ballast for Downlighting Applications

15

ML4835

PHYSICAL DIMENSIONS inches (millimeters)

Package: S20

20-Pin SOIC

0.498 - 0.512

20

(12.65 - 13.00)

0.024 - 0.034
(0.61 - 0.86)

(4 PLACES)

0.090 - 0.094
(2.28 - 2.39)

0.291 - 0.301
(7.39 - 7.65)

PIN 1 ID

1

0.050 BSC
(1.27 BSC)

0.012 - 0.020
(0.30 - 0.51)

0.095 - 0.107
(2.41 - 2.72)

SEATING PLANE

0.398 - 0.412

(10.11 - 10.47)

0.005 - 0.013
(0.13 - 0.33)

0º - 8º

0.022 - 0.042
(0.56 - 1.07)

0.007 - 0.015
(0.18 - 0.38)

Package: P20

20-Pin PDIP

1.010 - 1.035

(25.65 - 26.29)

20

16

0.060 MIN
(1.52 MIN)
(4 PLACES)

0.170 MAX
(4.32 MAX)

0.125 MIN

(3.18 MIN)

PIN 1 ID

1

0.055 - 0.065
(1.40 - 1.65)

0.016 - 0.022
(0.40 - 0.56)

0.100 BSC
(2.54 BSC)

SEATING PLANE

0.240 - 0.260
(6.09 - 6.61)

0.015 MIN
(0.38 MIN)

0.295 - 0.325
(7.49 - 8.26)

0º - 15º

0.008 - 0.012
(0.20 - 0.31)

PHYSICAL DIMENSIONS inches (millimeters)

ML4835

ORDERING INFORMATION

PART NUMBER TEMPERATURE RANGE PACKAGE

ML4835CP (End Of Life) 0°C to 70°C 20-Pin DIP (P20)
ML4835CS (End Of Life) 0°C to 70°C 20-Pin SOIC (S20)

© Micro Linear 1999. is a registered trademark of Micro Linear Corporation. All other trademarks are the property of their respective owners.

Products described herein may be covered by one or more of the following U.S. patents: 4,897,611; 4,964,026; 5,027,116; 5,281,862; 5,283,483; 5,418,502;
5,508,570; 5,510,727; 5,523,940; 5,546,017; 5,559,470; 5,565,761; 5,592,128; 5,594,376; 5,652,479; 5,661,427; 5,663,874; 5,672,959; 5,689,167; 5,714,897;
5,717,798; 5,742,151; 5,747,977; 5,754,012; 5,757,174; 5,767,653; 5,777,514; 5,793,168; 5,798,635; 5,804,950; 5,808,455; 5,811,999; 5,818,207; 5,818,669;
5,825,165; 5,825,223; 5,838,723; 5.844,378; 5,844,941. Japan: 2,598,946; 2,619,299; 2,704,176; 2,821,714. Other patents are pending.

Micro Linear reserves the right to make changes to any product herein to improve reliability, function or design. Micro Linear does not assume any liability
arising out of the application or use of any product described herein, neither does it convey any license under its patent right nor the rights of others. The circuits
contained in this data sheet are offered as possible applications only. Micro Linear makes no warranties or representations as to whether the illustrated circuits
infringe any intellectual property rights of others, and will accept no responsibility or liability for use of any application herein. The customer is urged to consult
with appropriate legal counsel before deciding on a particular application.

DS4835-03

2092 Concourse Drive

San Jose, CA 95131

Tel: [phone]

Fax: [phone]

www.microlinear.com

17