MAX6968AUE+ Maxim Integrated Products, MAX6968AUE+ Datasheet - Page 7

• Manufacturer Part Number: MAX6968AUE+
• Description: IC LED DRIVER LINEAR 16-TSSOP
• Manufacturer: Maxim Integrated Products
• Type: Linear (Serial Interface)r

Specifications of MAX6968AUE+

• Constant Current: Yes
• Topology: 8-Bit Shift Register, Open Drain, PWM
• Number Of Outputs: 8
• Internal Driver: Yes
• Type - Primary: General Purpose
• Voltage - Supply: 3 V ~ 5.5 V
• Voltage - Output: 5.5V
• Mounting Type: Surface Mount
• Package / Case: 16-TSSOP Exposed Pad, 16-eTSSOP, 16-HTSSOP
• Operating Temperature: -40°C ~ 125°C
• Current - Output / Channel: 55mA
• Internal Switch(s): No
• Number Of Segments: 16
• Low Level Output Current: 60 mA
• Operating Supply Voltage: 3 V to 5.5 V
• Maximum Supply Current: 25 mA
• Maximum Power Dissipation: 1702 mW
• Maximum Operating Temperature: + 85 C
• Mounting Style: SMD/SMT
• Minimum Operating Temperature: - 40 C
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant
• Frequency: -
• Efficiency: -
• Lead Free Status / Rohs Status: Details

The MAX6968 LED driver comprises a 4-wire serial
interface driving eight constant-current sinking open-
drain output ports. The outputs drive LEDs in either
static or multiplex applications (Figure 1). The constant-
current outputs are guaranteed for current accuracy
not only with chip-supply voltage variations (5V ±10%
and 3V to 5.5V), but also over a realistic range of driver
output voltage drop (0.5V to 2.5V). The drivers use cur-
rent-sensing feedback circuitry (not simple current mir-
rors) to ensure very small current variations over the full
allowed range of output voltage (see the Typical
Operating Characteristics).
The 4-wire serial interface comprises an 8-bit shift reg-
ister and an 8-bit transparent latch. The shift register is
written through a clock input CLK and a data input DIN
and the data propagates to a data output DOUT. The
data output allows multiple drivers to be cascaded and
operated together. The contents of the 8-bit shift regis-
ter are loaded into the transparent latch through a latch
enable input LE. The latch is transparent to the shift
register outputs when high, and latches the current
state on the falling edge of LE.
Figure 2. 4-Wire Serial-Interface Timing Diagram
DOUT
OUT_
CLK
DIN
OE
LE
8-Port, 5.5V Constant-Current LED Driver
_______________________________________________________________________________________
Detailed Description
t
DS
D7
t
DH
t
CL
t
OEL
D6
t
f
t
CH
t
OEW
80%
20%
Each driver output is an open-drain constant-current
sink that should be connected to the cathode of either
a single LED or a series string of multiple LEDs. The
LED anode can be connected to a supply voltage of up
to 5.5V, independent of the MAX6968 supply, V+. The
constant-current capability is up to 55mA per output,
set for all eight outputs by an external resistor, R
An internal reset circuit clears the internal registers of
the MAX6968 on power-up. All outputs OUT0–OUT7,
therefore, initialize high impedance, and the interface
output DOUT initializes low, regardless of the initial
logic levels of the CLK, DIN, OE, and LE inputs.
The serial interface on the MAX6968 is a 4-wire serial
interface using four inputs (DIN, CLK, LE, OE) and a
data output (DOUT). This interface is used to write dis-
play data to the MAX6968. The serial-interface data
word length is 8 bits, D0–D7. See Figure 2.
The functions of the five interface pins are as follows.
DIN is the serial data input, and must be stable when it
is sampled on the rising edge of CLK. Data is shifted in,
MSB first. This means that data bit D7 is clocked in first,
followed by 7 more data bits finishing with the LSB D0.
t
OEH
D1
t
r
t
DO
t
CP
Initial Power-Up and Operation
.
D0
t
LS
D7
t
t
LW
LF
4-Wire Serial Interface
SET
.
7