Datasheet

R
T
R
c
C
c
R
f
R
g
R
s
V
IN
R
p
R
c
C
c
R
f
R
1
R
s
V
IN
a) Non-inverting
b) Inverting
HIpin =COMP
1
RRR
sg
+=
gfEQ
RRR ||=
Tsp
RRR ||=
: 1 Constraint
: 2Costraint
MHz90
1
d
RC
cc
2S
V/V))(
R
(
g
101 t
+ +
1
RR
EQp
+
R
c
R
f
LMH6629
www.ti.com SNOSB18G –APRIL 2010–REVISED MARCH 2013
The SOT-23-5 package has the following differences relative to the WSON-8 package:
1. No power down (shutdown) capability.
2. No COMP pin to set the minimum stable gain. SOT-23–5 package minimum stable gain is internally fixed to
be 10V/V.
3. No feedback (FB) pin.
From a performance point of view, the WSON-8 and the SOT-23-5 packages perform very similarly except in the
following areas:
1. SSBW, Peaking, and 0.1 dB Bandwidth: These differences are highlighted in the Typical Performance
Characteristics and the Electrical Characteristics tables. Most notable differences are with small signal (0.2
Vpp) and close to the minimum stable gain of 10V/V.
2. Distortion: It is possible to get slightly different distortion performance. The board layout, decoupling
capacitor return current routing strongly influences this
3. Output Current: In heavy current applications, there will be differences between these package types
because of the difference in their respective Thermal Resistances (θ
JA
).
COMPENSATION
The LMH6629 has two compensation settings that can be controlled by the COMP pin (WSON-8 package only).
The default setting is set through an internal pull down resistor and places the COMP pin at the logic 0 state. In
this configuration the on-chip compensation is set to the maximum and bandwidth is reduced to enable stability
at gains as low as 4V/V.
When this pin is driven to the logic 1 state, the internal compensation is decreased to allow higher bandwidth at
higher gains. In this state, the minimum stable gain is 10V/V. Due to the reduced compensation, slew rate and
large signal bandwidth are significantly enhanced for the higher gains.
As mentioned earlier, the SOT-23-5 package does not offer the two compensation settings that the WSON-8
offers. The SOT-23-5 is internally set for a minimum gain of 10 V/V.
It is possible to externally compensate the LMH6629 for any of the following reasons, as shown in Figure 53:
• To operate the SOT-23-5 package (which does not offer the COMP pin) at closed loop gains < 10V/V.
• To operate the WSON-8 package at gains below the minimum stable gain of 4V /V when the COMP pin is
LO. Note: In this case, Figure 53 “Constraint 1” may be changed to ≥ 4 V/V instead of ≥ 10 V/V.
• To operate either package at low gain and need maximum slew rate (COMP pin HI).
Figure 53. External Compensation
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