Overview

The CN7511 is a 1.5A step-down (buck) constant-current LED driver IC manufactured by Consonance Electronics. Housed in an 8-pin SOP package, it drives high-power single LEDs or multi-LED strings at continuous currents up to 1.5 Amperes from an input supply voltage range of 6.0V to 30.0V DC.

Utilizing high-side current sensing with a low 100 mV feedback threshold (VCSV_{CS}), the CN7511 minimizes power loss across the sense resistor and reaches up to 95% efficiency. Its EN pin accepts both high-frequency PWM dimming signals (100 Hz…50 kHz100\text{ Hz} \dots 50\text{ kHz}) and DC voltage analog dimming.

Quick reference

Input Supply Voltage (VIN)6.0 V to 30.0 V DC
Output LED CurrentUp to 1.5 A1.5\text{ A} continuous (Set by current sense resistor RCSR_{CS})
Sense Reference Voltage (VCS)100 mV100\text{ mV} low-loss high-side threshold
EfficiencyUp to 95%95\% typical
Dimming SupportPWM Dimming (100 Hz…50 kHz100\text{ Hz} \dots 50\text{ kHz}) & DC Analog Voltage Dimming
ProtectionThermal shutdown, Open-LED, Short-LED protection
PackageSOP-8 / SOP-8-EP

Pinout (SOP-8 Package)

text
             ┌───┴───┐
        GND 1│ 1   8 │ VIN (+6V to +30V)
         CS 2│       │ 7 SW (Switch Output)
         EN 3│ CN7511│ 6 SW
         NC 4│       │ 5 NC
             └───────┘
PinNameTypeDescription
1GNDPowerGround Reference (0 V)
2CSInputHigh-Side Current Sense Input (100 mV100\text{ mV} reference relative to VIN)
3ENInputEnable & Dimming Input (High = On; Low = Shutdown; PWM or DC Analog Input)
4, 5NCUnusedNo Internal Connection
6, 7SWOutputInternal MOSFET Switch Drain Pins
8VINPowerSupply Input (+6.0V to +30.0V DC)

LED Current Programming Formula

The constant LED current (ILEDI_{LED}) is set by resistor RCSR_{CS} connected between VIN (Pin 8) and CS (Pin 2):

ILED=100 mVRCS=0.10VRCSI_{LED} = \frac{100\text{ mV}}{R_{CS}} = \frac{0.10\text{V}}{R_{CS}}

For ILED=1.0 A  ⟹  RCS=0.10V1.0A=0.10 Ω  (1W).\text{For } I_{LED} = 1.0\text{ A} \implies R_{CS} = \frac{0.10\text{V}}{1.0\text{A}} = 0.10\ \Omega\ \ (1\text{W}).

Common mistakes

  • Leaving EN (Pin 3) floating: EN has an internal pull-down resistor. Leaving EN disconnected holds the IC in shutdown (0 mA0\text{ mA}). Connect EN to VIN or 3.3V/5V microcontroller GPIO for active operation.

Notes

  • CN7511 vs PT4115: CN7511 delivers up to 1.5A in SOP-8; PT4115 delivers up to 1.2A in SOT-89-5.

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