MAX9975ARCCQ+TD Maxim Integrated, MAX9975ARCCQ+TD Datasheet - Page 28

• Manufacturer Part Number: MAX9975ARCCQ+TD
• Description: Buffers & Line Drivers
• Manufacturer: Maxim Integrated

Specifications of MAX9975ARCCQ+TD

• Rohs: yes

Dual, Low-Power, 1200Mbps ATE
Driver/Comparator with 35mA Load
Figure
The active load consists of linearly programmable,
Class AB source and sink current sources, a commuta-
tion buffer, and a diode bridge (see the Functional
Diagram). Analog control inputs LDH_ and LDL_ pro-
gram the sink and source currents, respectively, within
the 0 to 35mA range. Analog reference input COM_
sets the commutation buffer output voltage. The source
and sink naming convention is referenced to the DUT.
Current out of the MAX9975 constitutes sink current
and current into the MAX9975 constitutes source cur-
rent. The Class AB loads of the MAX9975 offer sub-
stantial efficiency improvement over conventional
active-load circuitry.
The programmed source (low) current loads the DUT
when V
current loads the DUT when V
High-speed differential input LDEN_ and 2 bits of the
control word (LDDIS and LLEAK) control the load
(Table 4). When the load is enabled, the internal source
and sink current sources connect to the diode bridge.
When the load is disabled, the internal current sources
28
OTHER CHANNEL
CHV_
DUT_
CLV_
FROM DUT_
______________________________________________________________________________________
3. Open-Collector Comparator Outputs
DUT
1
0
CDIFF
_ > V
V
EE
16mA
16mA
COM
_. The programmed sink (high)
DUT
4 x 50Ω
_ < V
MAX9975
COM
Active Load
1Ω
1Ω
_.
CH_
NCH_
V
CL_
NCL_
CCO_
Table
shunt to ground and the top and bottom of the bridge
float (see the Functional Diagram). LLEAK places the
load in low-leakage mode, and overrides LDEN_. See the
Low-Leakage Mode, LLEAK section for more detailed
information.
In some tester configurations, the load enable is driven
with the complement of the driver high-impedance sig-
nal (RCV_), so disabling the driver enables the load
and vice versa. The LDDIS signal allows the load to be
disabled independent of the state of LDEN_ (Table 4).
GS is the ground-sense input. A level-setting DAC, such
as the MAX5631 or MAX5734, programs the MAX9975’s
active load, driver, comparator, and clamps. Although
all the DAC levels are typically offset by V
tion of the MAX9975’s ground-sense input nullifies this
offset with respect to the active-load current. Connect
GS to the same ground reference used by the DAC.
(V
(V
To maintain an 8V range in the presence of GS variations,
GS offsets DHV_, DLV_, DTV_, CPHV_, CPLV_, and
COM_ ranges. Adequate supply headroom must be
maintained in the presence of GS variations. Ensure:
Asserting LLEAK through the serial port or with RST
places the MAX9975 into a very low-leakage state (see
the Electrical Characteristics table). With LLEAK assert-
ed, the comparators function at a reduced speed, and
CONNECTIONS
LDH
LDL
EXTERNAL
LDEN_
_ - V
_ - V
0
1
X
X
4. Active-Load Programming
V
V
V
V
CC
CC
EE
EE
GS
GS
≥ 10.0V + Max(V
) sets the sink current by -10mA/V.
≤ -4.5V + Min(V
≤ -4.0V + Min(V
≥ 9.5V + Max(V
) sets the source current by +10mA/V.
LDDIS
INTERNAL
REGISTER
CONTROL
0
0
1
X
Low-Leakage Mode, LLEAK
LLEAK
0
0
0
1
GS
GS
GS
GS
) (MAX9975AR)
) (MAX9975AR)
) (MAX9975AZ)
) (MAX9975AZ)
Normal operating mode,
Normal operating mode,
Low-leakage mode
Load disabled
load disabled
load enabled
GS
MODE
, the opera-
GS Input
LDDIS