Diodes PAM99700 User Manual

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Description

The PAM99700 is an open loop current mode control LED driver IC.

The PAM99700 can be programmed to operate in either a constant

frequency or constant off-time mode. It includes a 12 - 500V regulator

which allows it to work from a wide range of input voltages without the

need for an external low voltage supply. The PAM99700 includes a

PWM dimming input that can accept an external control signal with a

duty ratio of 0 - 100% and a frequency of up to a few kilohertz. It also

includes a 0 - 250mV linear dimming input which can be used for

linear dimming of the LED current.

The PAM99700 is ideally suited for buck LED drivers. Since the

PAM99700 operates in open loop current mode control, the controller

achieves good output current regulation without the need for any loop

compensation. PWM dimming response is limited only by the rate of

rise and fall of the inductor current, enabling very fast rise and fall

times. The PAM99700 requires only three external components (apart

from the power stage) to produce a controlled LED current making it

an ideal solution for low cost LED drivers.

Features

UNIVERSAL HIGH BRIGHTNESS LED DRIVER

Pin Assignments

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PAM99700

• Switch Mode Controller for Single Switch LED Drivers

• Open Loop Peak Current Controller

• Constant Frequency or Constant Off-Time Operation

• Linear and PWM Dimming Capability

• Requires Few External Components for Operation

• Application From a Few mA to More than 1A Output

PAM99700

Document number: DSxxxxx Rev. 1 - 1

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Applications

• DC/DC or AC/DC LED Driver Applications

• RGB Backlighting LED Driver

• Back Lighting of Flat Panel Displays

• General Purpose Constant Current Source

• Signage and Decorative LED Lighting

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Typical Applications Circuit

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PAM99700

Pin Descriptions

Pin

Name

VIN 1 1

CS 2 4

GND 3 5

GATE 4 8

PWMD 5 9

VDD 6 12

LD 7 13

RT 8 14

NC —

PAM99700

Document number: DSxxxxx Rev. 1 - 1

Pin Number

SOP-8 SOP-16

This pin is the input of a 12V-500V regulator.

This pin is the current sense pin used to sense the FET current by means of an external sense
resistor. When this pin exceeds the lower of either the internal 250mV or the voltage at the LD pin,
the gate output goes low.

Ground return for all internal circuitry. This pin must be electrically connected to the ground of the
power train.

This pin is the output gate driver for an external N-Channel power MOSFET.

This is the PWM dimming input of the IC. When this pin is pulled to GND, the gate driver is turned
off. When the pin is pulled high, the gate driver operates normally.

This is the power supply pin for all internal circuits. It must be bypassed with a low ESR capacitor
to GND (~ 10μF).

This pin is the linear dimming input an d sets the current sense threshold as long as the voltage at
the pin is less than 250mV (typ).

This pin sets the oscillator frequency. When a resistor is connected between RT and GND, the
PAM99700 operates in constant frequency mode. When the resistor is connected between RT
and GATE, the IC operates in constant off-time mode.

2, 3, 6, 7,

10, 11, 15, 16

Not connected.

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Function

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Functional Block Diagram

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PAM99700

Absolute Maximum Ratings (@T

These are stress ratings only and functional operation is not implied. Exposure to absolute maximum ratings for prolonged time periods may
affect device reliability. All voltages are with respect to ground.

Parameter Rating Unit

Maximum Junction Temperature 150

Storage Temperature -65 to +150

Soldering Temperature 300, 5sec

Recommended Operating Conditions (@T

Parameter Rating Unit

Supply Voltage 12 to 500 V

Ambient Temperature Range -40 to +85 °C

Junction Temperature Range -40 to +125 °C

= +25°C, unless otherwise specified.)

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°C

= +25°C, unless otherwise specified.)

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Thermal Information

Parameter Package Symbol Max Unit

Thermal Resistance (Junction to Ambient)

PAM99700

Document number: DSxxxxx Rev. 1 - 1

SOP-8

SOP-16 110

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115

°C/W

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PAM99700

Electrical Characteristics (@T

Parameter Symbol Test Conditions Min Typ Max Units

Input Voltage Range

Shutdown Mode Supply Current

Internally Regulated Voltage

Current Sense Pul-In Threshold Voltage

Current Sense Blanking Interval

Gate Sourcing Current

Gate Sinking Current

Gate Output Rise Time

Gate Output Fall Time

Oscillator Frequency

EN Threshold High

EN Threshold Low

Over Temperature Protection OTP 160 °C

OTP Hysteresis OTH 50 °C

PAM99700

Document number: DSxxxxx Rev. 1 - 1

= +25°C, unless otherwise specified.)

A

V

INDC

I

INSD

V

DD

V

CS,TH

T

BLANK

I

SOURCE

I

SINK

t

RISE

t

TALL

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OSC

V

EH

V

EL

DC Input Voltage

Pin PWMD to GND

VIN > 20V

250 mV

250 Ns

V

V

C

C

= 0V

GATE

= VDD

GATE

= 1nF

GATE

= 1nF

GATE

= 510kΩ

R

T

RT = 226kΩ

VIN = 12V to 500V

VIN = 12V to 500V

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12 500 V

0.1 mA

6 10 V

0.2 A

0.2 A

30 50 ns

30 50 ns

37 41 49

74 92 110

kHz

2.4 V

1.0 V

October 2012

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