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CAT3612
Programmable 300mA Camera Flash LED Driver
FEATURES
Dual matched regulated LED channels 300mA output current (150mA per channel) 1-wire EZDimTM Programmable LED Current 32 accurate dimming levels Power efficiency up to 90% Fractional pump 1x/1.5x Low noise input ripple Fixed High Frequency Operation 1MHz "Zero" Current Shutdown Mode Soft start and current limiting Short circuit protection Thermal shutdown protection 12-lead TDFN 3mm x 3mm package
PRODUCT DESCRIPTION
The CAT3612 is a high-efficiency 1x/1.5x fractional charge pump with programmable current in two LED channels. Each channel delivers accurate regulated current up to 150mA and make CAT3612 ideal for driving one or two flash LEDs. Low noise operation is achieved by operating at a constant switching frequency of 1MHz which allows the use of small external ceramic capacitors. The 1x/1.5x fractional charge pump supports a wide range of input voltages from 3V to 5.5V with efficiency up to 90%, and is ideal for Li-Ion battery powered devices. The EN/DIM logic input provides a 1-wire EZDimTM interface for dimming control of the LEDs. When enabled, pulsing the EN/DIM reduces the LED current on each negative edge in 31 linear steps from 150mA down to zero current. The device is available in the tiny 12-lead thin DFN 3mm x 3mm package with a max height of 0.8mm.
APPLICATION
Camera Flash Cellular Phones Digital Still Cameras
ORDERING INFORMATION
Part Number Package Quantity Package per Reel Marking 2000 HAAD
CAT3612HV2-T2 TDFN-12 3x3 Green *
Note *: Plated lead finish is Matte Tin. For other lead finish option, please contact factory.
PIN CONFIGURATION
Top View
TYPICAL APPLICATION CIRCUIT
12-lead TDFN 3mm x 3mm
Note: Unused LED channel must be connected to VOUT
(c) 2006 Catalyst Semiconductor, Inc.
Characteristics subject to change without notice
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Doc. No. 5016 Rev. A
CAT3612
ABSOLUTE MAXIMUM RATINGS
Parameter VIN, LED1, LED2 voltage VOUT, C1, C2 voltage EN/DIM voltage Storage Temperature Range Junction Temperature Range Lead Temperature Rating 6 7 VIN + 0.7V -65 to +160 -40 to +125 300 Unit V V V C C C
RECOMMENDED OPERATING CONDITIONS
Parameter VIN Ambient Temperature Range ILED per LED pin Total Output Current Range 3 to 5.5 -40 to +85 0 to 150 0 to 300 Unit V C mA mA
Typical application circuit with external components is shown on page 1.
ELECTRICAL OPERATING CHARACTERISTICS
(over recommended operating conditions unless specified otherwise) VIN = 3.6V, EN = High, ambient temperature of 25C. Symbol Parameter IQ Quiescent Current IQSHDN ILED-ACC ILED-DEV ROUT FOSC ISC_MAX IIN_MAX IEN/DIM VHI VLO TSD THYS VUVLO Shutdown Current LED Current Accuracy LED Channel Matching Output Resistance (open loop) Charge Pump Frequency Output short circuit Current Limit Input Current Limit EN/DIM Pin * Input Leakage * Logic High Level * Logic Low Level Thermal Shutdown Thermal Hysteresis Undervoltage lock out (UVLO) Threshold Conditions 1x mode, no load 1.5x mode, no load VEN = 0V 5mA ILED 150mA (ILED - ILEDAVG) / ILEDAVG 1x mode, IOUT = 100mA 1.5x mode, IOUT = 100mA VOUT < 0.5V 1x mode, VOUT > 1V -1 1.3 165 20 2 Min Typ 0.5 3 3 3 0.4 2.6 1 60 350 Max Unit mA mA A % % MHz mA mA A V V C C V
1
0.8
1.3
1 0.4
Doc. No. 5016 Rev. A
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(c) 2006 Catalyst Semiconductor, Inc. Characteristics subject to change without notice
CAT3612
RECOMENDED EN/DIM TIMING For 3V VIN 5.5V, over full ambient temperature range -40C to +85C. Symbol TSETP TLO THI TOFF TD TDEC Parameter EN/DIM setup from shutdown EN/DIM program low time EN/DIM program high time EN/DIM low time to shutdown LED current enable LED current decrement Conditions Min 10 0.3 0.3 1.5 Typ Max 200 Unit s s s ms s s
40 0.1
Figure 1. LED Dimming Timing Diagram
(c) 2006 Catalyst Semiconductor, Inc.
Characteristics subject to change without notice
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Doc. No. 5016 Rev. A
CAT3612
TYPICAL CHARACTERISTICS VIN = 3.6V, IOUT = 100mA, CIN = COUT = 2.2F, C1 = C2 = 1F, TAMB = 25C unless otherwise specified. Efficiency vs. Input Voltage
100 90 EFFICIENCY [%] 80 70 60 IOUT = 250mA 50 IOUT = 100mA 40 4.2 4.0 3.8 3.6 3.4 3.2 INPUT VOLTAGE [V] 3.0 VF = 3.4V VF = 3V
Efficiency vs. LED Current
100 90 EFFICIENCY [%] 80 70 60 50 40 50 100 150 200 250 LED CURRENT [mA] 300 VIN = 3.2V (1.5x Mode) VIN = 4.2V (1x Mode)
Quiescent Current vs. Input Voltage (1x mode)
0.8 QUIESCENT CURRENT [mA]
Quiescent Current vs. Temperature (1x mode)
0.8 QUIESCENT CURRENT [mA] 0.6 0.4 0.2 LED Off 0.0 -40 0 40 80 TEMPERATURE [C] 120
0.6 0.4 0.2 LED Off 0.0 3.0 3.2 3.4 3.6 3.8 4.0 INPUT VOLTAGE [V] 4.2
Quiescent Current vs. Input Voltage (1.5x mode)
6.0 QUIESCENT CURRENT [mA]
Quiescent Current vs. Temperature (1.5x mode)
6.0 QUIESCENT CURRENT [mA] 5.0 4.0 3.0 2.0 1.0 0.0 -40 0 40 80 TEMPERATURE [C] 120 LED Off
5.0 4.0 3.0 2.0 1.0 LED Off 0.0 3.0 3.2 3.4 3.6 3.8 4.0 INPUT VOLTAGE [V] 4.2
Doc. No. 5016 Rev. A
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(c) 2006 Catalyst Semiconductor, Inc. Characteristics subject to change without notice
CAT3612
TYPICAL CHARACTERISTICS VIN = 3.6V, IOUT = 100mA, CIN = COUT = 2.2F, C1 = C2 = 1F, TAMB = 25C unless otherwise specified. LED Current Change vs. Input Voltage
5.0 4.0 3.0 2.0 1.0 0.0 -1.0 -2.0 -3.0 -4.0 -5.0 LED CURRENT CHANGE [%]
LED Current Change vs. Temperature
5.0 4.0 3.0 2.0 1.0 0.0 -1.0 -2.0 -3.0 -4.0 -5.0 -40 0 40 80 TEMPERATURE [C] 120 LED CURRENT CHANGE [%]
1x Mode
1.5x Mode
3.0
3.2 3.4 3.6 3.8 4.0 INPUT VOLTAGE [V]
4.2
Oscillator Frequency vs. Input Voltage
1.3 CLOCK FREQUENCY [MHz]
Oscillator Frequency vs. Temperature
1.3 CLOCK FREQUENCY [MHz] 1.2 1.1 1.0 0.9 0.8 0.7 -40 0 40 80 TEMPERATURE [C] 120
1.2 1.1 1.0 0.9 0.8 0.7 3.0 3.2 3.4 3.6 3.8 INPUT VOLTAGE [V] 4.0
Output Resistance vs. Input Voltage (1x mode)
1.0 OUTPUT RESISTANCE [] .
Output Resistance vs. Input Voltage(1.5x mode)
4.0 OUTPUT RESISTANCE [] . 3.5 3.0 2.5 2.0 1.5 1.0 3.0 3.2 3.4 3.6 3.8 4.0 INPUT VOLTAGE [V] 4.2
0.8 0.6 0.4 0.2 0.0 3.0 3.2 3.4 3.6 3.8 4.0 INPUT VOLTAGE [V] 4.2
(c) 2006 Catalyst Semiconductor, Inc.
Characteristics subject to change without notice
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Doc. No. 5016 Rev. A
CAT3612
TYPICAL CHARACTERISTICS VIN = 3.6V, IOUT = 100mA, CIN = COUT = 2.2F, C1 = C2 = 1F, TAMB = 25C unless otherwise specified. Power Up with 1 LED at 100mA (1x Mode) Power Up with 1 LED at 100mA (1.5x Mode)
Enable Power Down Delay (1x Mode)
Enable Power Down Delay (1.5x Mode)
Switching Waveforms in 1.5x Mode
Operating Waveforms in 1x Mode
Doc. No. 5016 Rev. A
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(c) 2006 Catalyst Semiconductor, Inc. Characteristics subject to change without notice
CAT3612
TYPICAL CHARACTERISTICS VIN = 3.6V, IOUT = 100mA, CIN = COUT = 2.2F, C1 = C2 = 1F, TAMB = 25C unless otherwise specified. Enable and Output Current Dimming Waveforms Line Transient Response (3.6V to 5.5V) 1x Mode
Enable High Minimum Program Time vs. Temperature
200
Enable Low Minimum Program Time vs. Temperature
200 VIN = 3.5V MINIMUM TIME [nS] . 160 120 VIN = 4.2V 80 40 0
MINIMUM TIME [nS] .
160 VIN = 3.5V 120 80 VIN = 4.2V 40 0 -40 0 40 80 TEMPERATURE [C] 120
-40
0
40
80
120
TEMPERATURE [C]
Enable Voltage Threshold vs. Temperature
1.2 EN A B LE V OLTA G E [V ]
Foldback Current Limit
4.0 OUTPUT VOLTAGE [V] 3.5 3.0 2.5 2.0 1.5 1.0 0.5 0.0 0 100 200 300 400 OUTPUT CURRENT [mA] 500 1x Mode LED Off
1.0 0.8 0.6 0.4 0.2 0.0 -40 0 40 80 120 TEMPERATURE [C]
(c) 2006 Catalyst Semiconductor, Inc.
Characteristics subject to change without notice
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Doc. No. 5016 Rev. A
CAT3612
PIN DESCRIPTIONS
Pin # 1 2 3 4 5 6 7 8 9 10 11 12 TAB Name VIN C1+ C1C2GND LED1 LED2 C2+ EN/DIM VOUT TAB Function Supply voltage. Bucket capacitor 1 terminal Bucket capacitor 1 terminal Bucket capacitor 2 terminal Ground reference LED1 cathode terminal (if not used, connect to VOUT)1. LED2 cathode terminal (if not used, connect to VOUT)1. Bucket capacitor 2 terminal Not connected Device enable (active high) and dimming control input. Not connected Charge pump output connected to the LED anodes. Connect to GND on the PCB.
Note 1: LED1, LED2 pins should not be left floating. They should be connected to the LED cathode, or tied to the VOUT pin if not used.
PIN FUNCTION
VIN is the supply pin for the device. A small 1F ceramic bypass capacitor is required between the VIN pin and ground near the device. The operating input voltage range is up to 5.5V. When the input supply falls below the undervoltage threshold (2V), all LEDs channels are disabled. EN/DIM is the enable and dimming control logic input for all LED channels. Guaranteed levels of logic high and logic low are set at 1.3V and 0.4V respectively. When EN/DIM is initially taken high, the device becomes enabled and the LED currents remain at 0mA. The falling edge of the first pulse on EN/DIM sets the LED currents to the full scale 150mA. On each consecutive falling edge of the pulse on EN/DIM, the LED current decreases by 150/31mA. On the 32nd pulse, the LED current is set to zero. The next pulse on EN/DIM resets the current back to full scale 150mA. To place the device into zero current shutdown mode, the EN/DIM pin must be held low for 1.5ms or more. VOUT is the charge pump output that is connected to the LED anodes. A small 1F ceramic bypass capacitor is required between the VOUT pin and ground near the device. GND is the ground reference for the charge pump. The pin must be connected to the ground plane on the PCB. C1+, C1- are connected to each side of the 1F ceramic bucket capacitor C1. C2+, C2- are connected to each side of the 1F ceramic bucket capacitor C2. LED1, LED2 provide the internal regulated current for each of the LED cathodes. These pins enter a high impedance zero current state whenever the device is in shutdown mode. In applications using only one LED channel, the unused channel should be tied directly to VOUT. The disabled channel only draws about 0.5mA. TAB is the exposed pad underneath the package. For best thermal performance, the tab should be soldered to the PCB and connected to the ground plane.
Doc. No. 5016 Rev. A
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(c) 2006 Catalyst Semiconductor, Inc. Characteristics subject to change without notice
CAT3612
BLOCK DIAGRAM
Figure 2. CAT3612 Functional Block Diagram
BASIC OPERATION
At power-up, the CAT3612 starts operating in 1x mode where the output will be approximately equal to the input supply voltage (less any internal voltage losses). If the output voltage is sufficient to regulate all LEDs currents the device remains in 1x operating mode. If the input voltage is insufficient or falls to a level where the regulated currents cannot be maintained, the device automatically switches (after a fixed of 400s) into 1.5x mode. In 1.5x mode, the output is approximately equal to 1.5 times the input supply voltage (less any internal voltage losses). The above sequence is repeated each and every time the chip is powered-up or is taken out of shutdown mode (via EN/DIM pin).
(c) 2006 Catalyst Semiconductor, Inc.
Characteristics subject to change without notice
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Doc. No. 5016 Rev. A
CAT3612
LED Current Setting
Figure 1 shows the EN/DIM input timing diagram for
setting the LED currents. The EN/DIM set-up time requires the signal to be held high for 10s or longer to ensure the initialization of the driver at power-up. Each subsequent pulse on the EN/DIM (300ns to 200s pulse duration) steps down the LED current from full scale of 150mA to zero with nearly 5mA resolution. The selection of the LED current per channel is shown in Table 1. Consecutive pulses should be separated by 300ns or longer. Pulsing beyond the 0mA level restores the current level back to full scale and the cycle repeats. Pulsing frequencies from 5kHz up to 1MHz can be supported during dimming operations. When the EN/DIM is held low for 1.5ms or more, the CAT3612 enters the shutdown mode and draws "zero" current. For applications with a single LED connected to one LED pin only, the unused LED pin must be tied to VOUT, as shown on Figure 3. Table 1. Selection of LED current per Channel Number of pulses on EN/DIM 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 LED current (mA) 150 145 140 135.5 131 126 121 116 111 106.5 101.5 97 92 87 82 77.5 72.5 68 63 58 53 48.5 43.5 39 34 29 24 19 14.5 10 5 0
Figure 3. Single LED on one LED pin
Figure 4. Application with 2 LEDs
Doc. No. 5016 Rev. A
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(c) 2006 Catalyst Semiconductor, Inc. Characteristics subject to change without notice
CAT3612
Protection mode
If an LED becomes open-circuit, the output voltage VOUT is internally limited to about 5.5V. This is to prevent the output pin from exceeding its absolute maximum rating. The driver enters a thermal shutdown mode as soon as the die temperature exceeds about +165C. When the device temperature drops down by about 20C, the device resumes normal operation.
Recommended Layout
In 1.5x charge pump mode, the driver switches internally at a high frequency of 1MHz. It is recommended to minimize trace length to all four capacitors. A ground plane should cover the area under the driver IC as well as the bypass capacitors. Short connection to ground on capacitors Cin and Cout can be implemented with the use of multiple via. A copper area matching the TDFN exposed pad (GND) must be connected to the ground plane underneath. The use of multiple via improves the package heat dissipation.
External components
The driver requires a total of four external 1F ceramic capacitors: two for decoupling input and output, and two for the charge pump. Both capacitor types X5R and X7R are recommended for the LED driver application. In the 1.5x charge pump mode, the input current ripple is kept very low by design, and an input bypass capacitor of 1F is sufficient. In 1x mode, the device operating in linear mode does not introduce switching noise back onto the supply.
Figure 5. Recommended Layout
(c) 2006 Catalyst Semiconductor, Inc.
Characteristics subject to change without notice
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Doc. No. 5016 Rev. A
CAT3612
PACKAGE DRAWING AND DIMENSIONS
Thin DFN 12-Lead 3mm x 3mm, 0.45mm Pitch
RECOMMENDED LAND PATTERN
Dimensions in millimeters
Doc. No. 5016 Rev. A
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(c) 2006 Catalyst Semiconductor, Inc. Characteristics subject to change without notice
REVISION HISTORY
Date 07/21/2006 Rev. A Reason Initial Issue
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Document No: 5016 Revision: A Issue date: 07/21/2006

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